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  • 1.
    Alenkvist, Ida
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Dyachok, Oleg
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Tian, Geng
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Li, Jia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Mehrabanfar, Saba
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Jin, Yang
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience.
    Birnir, Bryndis
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Tengholm, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Welsh, Michael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Absence of Shb impairs insulin secretion by elevated FAK activity in pancreatic islets2014In: Journal of Endocrinology, ISSN 0022-0795, E-ISSN 1479-6805, Vol. 223, no 3, p. 267-275Article in journal (Refereed)
    Abstract [en]

    The Src homology-2 domain containing protein B (SHB) has previously been shown to function as a pleiotropic adapter protein, conveying signals from receptor tyrosine kinases to intracellular signaling intermediates. The overexpression of Shb in β-cells promotes β-cell proliferation by increased insulin receptor substrate (IRS) and focal adhesion kinase (FAK) activity, whereas Shb deficiency causes moderate glucose intolerance and impaired first-peak insulin secretion. Using an array of techniques, including live-cell imaging, patch-clamping, immunoblotting, and semi-quantitative PCR, we presently investigated the causes of the abnormal insulin secretory characteristics in Shb-knockout mice. Shb-knockout islets displayed an abnormal signaling signature with increased activities of FAK, IRS, and AKT. β-catenin protein expression was elevated and it showed increased nuclear localization. However, there were no major alterations in the gene expression of various proteins involved in the β-cell secretory machinery. Nor was Shb deficiency associated with changes in glucose-induced ATP generation or cytoplasmic Ca(2) (+) handling. In contrast, the glucose-induced rise in cAMP, known to be important for the insulin secretory response, was delayed in the Shb-knockout compared with WT control. Inhibition of FAK increased the submembrane cAMP concentration, implicating FAK activity in the regulation of insulin exocytosis. In conclusion, Shb deficiency causes a chronic increase in β-cell FAK activity that perturbs the normal insulin secretory characteristics of β-cells, suggesting multi-faceted effects of FAK on insulin secretion depending on the mechanism of FAK activation.

  • 2.
    Babateen, Omar
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Jin, Zhe
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Bhandage, Amol K.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Korol, Sergiy V
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Westermark, Bengt
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Cancer and Vascular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Forsberg Nilsson, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Cancer and Vascular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Uhrbom, Lene
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Cancer and Vascular Biology.
    Smits, Anja
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Neurology.
    Birnir, Bryndis
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Neurology.
    Etomidate, propofol and diazepam potentiate GABA-evoked GABAA currents in a cell line derived from Human glioblastoma2015In: European Journal of Pharmacology, ISSN 0014-2999, E-ISSN 1879-0712, Vol. 748, p. 101-107Article in journal (Refereed)
    Abstract [en]

    GABAA receptors are pentameric chloride ion channels that are opened by GABA. We have screened a cell line derived from human glioblastoma, U3047MG, for expression of GABAA receptor subunit isoforms and formation of functional ion channels. We identified GABAA receptors subunit α2, α3, α5, β1, β2, β3, δ, γ3, π, and θ mRNAs in the U3047MG cell line. Whole-cell GABA-activated currents were recorded and the half-maximal concentration (EC50) for the GABA-activated current was 36μM. The currents were activated by THIP (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol) and enhanced by the benzodiazepine diazepam (1μM) and the general anesthetics etomidate and propofol (50μM). In line with the expressed GABAA receptors containing at least the α3β3θ subunits, the receptors were highly sensitive to etomidate (EC50=55nM). Immunocytochemistry identified expression of the α3 and β3 subunit proteins. Our results show that the GABAA receptors in the glial cell line are functional and are modulated by classical GABAA receptor drugs. We propose that the U3047MG cell line may be used as a model system to study GABAA receptors function and pharmacology in glial cells.

  • 3.
    Babateen, Omar
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Korol, Sergiy V.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Jin, Zhe
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Bhandage, Amol K.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Ahemaiti, Aikeremu
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Developmental Genetics.
    Birnir, Bryndis
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Liraglutide modulates GABAergic signaling in rat hippocampal CA3 pyramidal neurons predominantly by presynaptic mechanism2017In: BMC Pharmacology & Toxicology, E-ISSN 2050-6511, Vol. 18, article id 83Article in journal (Refereed)
    Abstract [en]

    Background

    γ-Aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the brain where it regulates activity of neuronal networks. The receptor for glucagon-like peptide-1 (GLP-1) is expressed in the hippocampus, which is the center for memory and learning. In this study we examined effects of liraglutide, a GLP-1 analog, on GABA signaling in CA3 hippocampal pyramidal neurons.

    Methods

    We used patch-clamp electrophysiology to record synaptic and tonic GABA-activated currents in CA3 pyramidal neurons in rat hippocampal brain slices.

    Results

    We examined the effects of liraglutide on the neurons at concentrations ranging from one nM to one μM. Significant changes of the spontaneous inhibitory postsynaptic currents (sIPSCs) were only recorded with 100 nM liraglutide and then in just ≈50% of the neurons tested at this concentration. In neurons affected by liraglutide both the sIPSC frequency and the most probable amplitudes increased. When the action potential firing was inhibited by tetrodotoxin (TTX) the frequency and amplitude of IPSCs in TTX and in TTX plus 100 nM liraglutide were similar.

    Conclusions

    The results demonstrate that liraglutide regulation of GABA signaling of CA3 pyramidal neurons is predominantly presynaptic and more limited than has been observed for GLP-1 and exendin-4 in hippocampal neurons.

  • 4.
    Babateen, Omar M.
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Jin, Zhe
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Bhandage, Amol K.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Korol, Sergiy V.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Westermark, Bengt
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Neuro-Oncology.
    Nilsson, Karin Forsberg
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Neuro-Oncology.
    Uhrbom, Lene
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Neuro-Oncology.
    Smits, Anja
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Neurology.
    Birnir, Bryndis
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Neurology.
    GABA-A receptor currents in a cell line (U3047MG) derived from a human glioblastoma tumor are enhanced by etomidate, propofol and diazepam2014In: Acta Physiologica, ISSN 1748-1708, E-ISSN 1748-1716, Vol. 211, no S696, p. 100-100, article id P74Article in journal (Other academic)
  • 5. Barragan, A.
    et al.
    Weidner, J. M.
    Jin, Zhe
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Korpi, E. R.
    Birnir, Bryndis
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    GABAergic signalling in the immune system2015In: Acta Physiologica, ISSN 1748-1708, E-ISSN 1748-1716, Vol. 213, no 4, p. 819-827Article, review/survey (Refereed)
    Abstract [en]

    The GABAergic system is the main inhibitory neurotransmitter system in the central nervous system (CNS) of vertebrates. Signalling of the transmitter c-aminobutyric acid (GABA) via GABA type A receptor channels or G-protein-coupled type B receptors is implicated in multiple CNS functions. Recent findings have implicated the GABAergic system in immune cell functions, inflammatory conditions and diseases in peripheral tissues. Interestingly, the specific effects may vary between immune cell types, with stage of activation and be altered by infectious agents. GABA/GABA-A receptor-mediated immunomodulatory functions have been unveiled in immune cells, being present in T lymphocytes and regulating the migration of Toxoplasma-infected dendritic cells. The GABAergic system may also play a role in the regulation of brain resident immune cells, the microglial cells. Activation of microglia appears to regulate the function of GABAergic neurotransmission in neighbouring neurones through changes induced by secretion of brain-derived neurotrophic factor. The neurotransmitter-driven immunomodulation is a new but rapidly growing field of science. Herein, we review the present knowledge of the GABA signalling in immune cells of the periphery and the CNS and raise questions for future research.

  • 6.
    Bhandage, Amol
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Hellgren, Charlotte
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Women's and Children's Health, Obstetrics and Gynaecology.
    Jin, Zhe
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Ólafsson, Einar
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Sundström Poromaa, Inger
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Women's and Children's Health, Obstetrics and Gynaecology.
    Birnir, Bryndis
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    The mRNA expression of GABA-A, GABA-B receptor subunits and chloride transporters in peripheral blood mononuclear cells is influenced by gender, pregnancy and depression2015In: Acta Physiologica, ISSN 1748-1708, E-ISSN 1748-1716, Vol. 215, p. 91-91Article in journal (Other academic)
  • 7.
    Bhandage, Amol
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Jin, Zhe
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Korol, Sergiy V
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Tafreshiha, Atieh
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Gohel, Priya
    Stockholm Univ, Wenner Gren Inst, Dept Mol Biosci, Stockholm, Sweden.
    Hellgren, Charlotte
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Women's and Children's Health, Research group (Dept. of women´s and children´s health), Reproductive Health.
    Espes, Daniel
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Carlsson, Per-Ola
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Sundström Poromaa, Inger
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Women's and Children's Health, Research group (Dept. of women´s and children´s health), Reproductive Health.
    Birnir, Bryndis
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Expression of calcium release-activated and voltage-gated calcium channels genes in peripheral blood mononuclear cells is altered in pregnancy and in type 1 diabetes2018In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 13, no 12, article id e0208981Article in journal (Refereed)
    Abstract [en]

    Calcium (Ca2+) is an important ion in physiology and is found both outside and inside cells. The intracellular concentration of Ca2+ is tightly regulated as it is an intracellular signal molecule and can affect a variety of cellular processes. In immune cells Ca2+ has been shown to regulate e.g. gene transcription, cytokine secretion, proliferation and migration. Ca2+ can enter the cytoplasm either from intracellular stores or from outside the cells when Ca2+ permeable ion channels in the plasma membrane open. The Ca2+ release-activated (CRAC) channel is the most prominent Ca2+ ion channel in the plasma membrane. It is formed by ORAI1-3 and the channel is opened by the endoplasmic reticulum Ca2+ sensor proteins stromal interaction molecules (STIM) 1 and 2. Another group of Ca-2(+) channels in the plasma membrane are the voltage-gated Ca2+ (Ca-V) channels. We examined if a change in immunological tolerance is accompanied by altered ORAI, STIM and Ca-V gene expression in peripheral blood mononuclear cells (PBMCs) in pregnant women and in type 1 diabetic individuals. Our results show that in pregnancy and type 1 diabetes ORAI1-3 are up-regulated whereas STIM1 and 2 are down-regulated in pregnancy but only STIM2 in type 1 diabetes. Expression of L-, P/Q-, R- and T-type voltage-gated Ca2+ channels was detected in the PBMCs where the Ca(V)2.3 gene was up-regulated in pregnancy and type 1 diabetes whereas the Ca(V)2.1 and Ca(V)3.2 genes were up-regulated only in pregnancy and the Ca(V)1.3 gene in type 1 diabetes. The results are consistent with that expression of ORAI, STIM and Ca-V genes correlate with a shift in immunological status of the individual in health, as during pregnancy, and in the autoimmune disease type 1 diabetes. Whether the changes are in general protective or in type 1 diabetes include some pathogenic components remains to be clarified.

  • 8.
    Bhandage, Amol K.
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Hellgren, Charlotte
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Women's and Children's Health, Obstetrics and Gynaecology.
    Jin, Zhe
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Olafsson, Einar B
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience.
    Sundström-Poromaa, Inger
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Women's and Children's Health, Obstetrics and Gynaecology.
    Birnir, Bryndis
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Expression of GABA receptors subunits in peripheral blood mononuclear cells is gender dependent, altered in pregnancy and modified by mental health2015In: Acta Physiologica, ISSN 1748-1708, E-ISSN 1748-1716, Vol. 213, no 3, p. 575-585Article in journal (Refereed)
    Abstract [en]

    AIM: The concept of nerve-driven immunity recognizes a link between the nervous and the immune system. γ-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the brain and receptors activated by GABA can be expressed by immune cells. Here we examined if the expression of GABA receptors and chloride transporters in human peripheral mononuclear cells (PBMCs) were influenced by gender, pregnancy or mental health.

    METHODS: We used RT-qPCR to determine the mRNA expression level in men (n=16), non-pregnant women (n=19), healthy pregnant women (n=27) and depressed pregnant women (n=15).

    RESULTS: The ρ2 subunit had the most prominent expression level of the GABA-A receptor subunits in all samples. The δ and ρ2 subunits were up-regulated by pregnancy whereas the ε subunit was more frequently expressed in healthy pregnant women than non-pregnant women who, in-turn, commonly expressed the α6 and the γ2 subunits. The β1 and ε subunits expression was altered by depression in pregnant women. The GABA-B1 receptor was up-regulated by depression in pregnant women while the transporters NKCC1 and KCC4 were down-regulated by pregnancy. The changes recorded in the mRNA expression levels imply participation of GABA receptors in establishing and maintaining tolerance in pregnancy. Importantly, the correlation of mental health with the expression of specific receptor subunits reveals a connection between the immune cells and the brain. Biomarkers for mental health may be identified in PBMCs.

    CONCLUSION: The results demonstrate the impact gender, pregnancy and mental health have on expression of GABA receptors plus chloride transporters expressed in human PBMCs.

  • 9.
    Bhandage, Amol K.
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Hellgren, Charlotte
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Women's and Children's Health, Obstetrics and Gynaecology.
    Jin, Zhe
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Olafsson, Einar
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience.
    Sundström, Iinger Poromaa
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Women's and Children's Health, Obstetrics and Gynaecology.
    Birnir, Bryndis
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    GABA-A receptor subunit expression in human peripheral blood mononuclear cells2014In: Acta Physiologica, ISSN 1748-1708, E-ISSN 1748-1716, Vol. 211, no S696, p. 86-86, article id P45Article in journal (Other academic)
  • 10.
    Bhandage, Amol K.
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Jin, Zhe
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Bazov, Igor
    Kononenko, Olga
    Bakalkin, Georgy
    Korpi, Esa R
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Birnir, Bryndis
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    GABA-A and NMDA receptor subunit mRNA expression is altered in the caudate but not the putamen of the postmortem brains of alcoholics2014In: Frontiers in Cellular Neuroscience, ISSN 1662-5102, E-ISSN 1662-5102, Vol. 8, article id 415Article in journal (Refereed)
    Abstract [en]

    Chronic consumption of alcohol by humans has been shown to lead to impairment of executive and cognitive functions. Here, we have studied the mRNA expression of ion channel receptors for glutamate and GABA in the dorsal striatum of post-mortem brains from alcoholics (n = 29) and normal controls (n = 29), with the focus on the caudate nucleus that is associated with the frontal cortex executive functions and automatic thinking and on the putamen area that is linked to motor cortices and automatic movements. The results obtained by qPCR assay revealed significant changes in the expression of specific excitatory ionotropic glutamate and inhibitory GABA-A receptor subunit genes in the caudate but not the putamen. Thus, in the caudate we found reduced levels of mRNAs encoding the GluN2A glutamate receptor and the δ, ε, and ρ2 GABA-A receptor subunits, and increased levels of the mRNAs encoding GluD1, GluD2, and GABA-A γ1 subunits in the alcoholics as compared to controls. Interestingly in the controls, 11 glutamate and 5 GABA-A receptor genes were more prominently expressed in the caudate than the putamen (fold-increase varied from 1.24 to 2.91). Differences in gene expression patterns between the striatal regions may underlie differences in associated behavioral outputs. Our results suggest an altered balance between caudate-mediated voluntarily controlled and automatic behaviors in alcoholics, including diminished executive control on goal-directed alcohol-seeking behavior.

  • 11.
    Bhandage, Amol K.
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Jin, Zhe
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Hellgren, Charlotte
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Women's and Children's Health.
    Korol, Sergiy V.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Nowak, Krzysztof
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience.
    Williamsson, Louise
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience.
    Sundström-Poromaa, Inger
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Women's and Children's Health.
    Birnir, Bryndis
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    AMPA, NMDA and kainate glutamate receptor subunits are expressed in human peripheral blood mononuclear cells (PBMCs) where the expression of GluK4 is altered by pregnancy and GluN2D by depression in pregnant women2017In: Journal of Neuroimmunology, ISSN 0165-5728, E-ISSN 1872-8421, Vol. 305, p. 51-58Article in journal (Refereed)
    Abstract [en]

    The amino acid glutamate opens cation permeable ion channels, the iGlu receptors. These ion channels are abundantly expressed in the mammalian brain where glutamate is the main excitatory neurotransmitter. The neurotransmitters and their receptors are being increasingly detected in the cells of immune system. Here we examined the expression of the 18 known subunits of the iGlu receptors families; alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), kainate, N-methyl-D-aspartate (NMDA) and delta in human peripheral blood mononuclear cells (PBMCs). We compared the expression of the subunits between four groups: men, non-pregnant women, healthy pregnant women and depressed pregnant women.

    Out of 18 subunits of the iGlu receptors, mRNAs for 11 subunits were detected in PBMCs from men and nonpregnant women; AMPA: GluA3, GluA4, kainate: GluK2, GluK4, GluK5, NMDA: GluN1, GluN2C, GluN2D, GluN3A, GluN3B, and delta: GluD1. In the healthy and the depressed pregnant women, in addition, the delta GluD2 subunit was identified. The mRNAs for GluK4, GluK5, GluN2C and GluN2D were expressed at a higher level than other subunits. Gender, pregnancy or depression during pregnancy altered the expression of GluA3, GluK4, GluN2D, GluN3B and GluD1 iGlu subunit mRNAs. The greatest changes recorded were the lower GluA3 and GluK4 mRNA levels in pregnant women and the higher GluN2D mRNA level in healthy but not in depressed pregnant women as compared to non-pregnant individuals. Using subunit specific antibodies, the GluK4, GluK5, GluNl, GluN2C and GluN2D subunit proteins were identified in the PBMCs. The results show expression of specific iGlu receptor subunit in the PBMCs and support the idea of physiology-driven changes of iGlu receptors subtypes in the immune cells.

  • 12.
    Bhandage, Amol K.
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Jin, Zhe
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Korol, Sergiy V.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology. Uppsala University.
    Shen, Qiujin
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Molecular tools.
    Pei, Yu
    Karolinska Institute, Stockholm, Sweden.
    Deng, Qiaolin
    Karolinska Institute, Stockholm, Sweden.
    Espes, Daniel
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Transplantation and regenerative medicine.
    Carlsson, Per-Ola
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Transplantation and regenerative medicine.
    Kamali-Moghaddam, Masood
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Molecular tools. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Birnir, Bryndis
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    GABA Regulates Release of Inflammatory Cytokines From Peripheral Blood Mononuclear Cells and CD4+ T Cells and Is Immunosuppressive in Type 1 Diabetes2018In: EBioMedicine, ISSN 0360-0637, E-ISSN 2352-3964, Vol. 30, p. 283-294Article in journal (Refereed)
    Abstract [en]

    The neurotransmitter γ-aminobutyric acid (GABA) is an extracellular signaling molecule in the brain and in pancreatic islets. Here, we demonstrate that GABA regulates cytokine secretion from human peripheral blood mononuclear cells (PBMCs) and CD4+ T cells. In anti-CD3 stimulated PBMCs, GABA (100nM) inhibited release of 47 cytokines in cells from patients with type 1 diabetes (T1D), but only 16 cytokines in cells from nondiabetic (ND) individuals. CD4+ T cells from ND individuals were grouped into responder or non-responder T cells according to effects of GABA (100nM, 500nM) on the cell proliferation. In the responder T cells, GABA decreased proliferation, and inhibited secretion of 37 cytokines in a concentration-dependent manner. In the non-responder T cells, GABA modulated release of 8 cytokines. GABA concentrations in plasma from T1D patients and ND individuals were correlated with 10 cytokines where 7 were increased in plasma of T1D patients. GABA inhibited secretion of 5 of these cytokines from both T1D PBMCs and ND responder T cells. The results identify GABA as a potent regulator of both Th1- and Th2-type cytokine secretion from human PBMCs and CD4+ T cells where GABA generally decreases the secretion.

  • 13.
    Birnir, Bryndis
    et al.
    Molecular and Cellular Physiology, Dept. of Physiological Sciences, Lund University.
    Eghbali, M
    Cox, G B
    Gage, P W
    GABA concentration sets the conductance of delayed GABAA channels in outside-out patches from rat hippocampal neurons.2001In: Journal of Membrane Biology, ISSN 0022-2631, E-ISSN 1432-1424, Vol. 181, no 3, p. 171-83Article in journal (Refereed)
    Abstract [en]

    GABAA channels were activated by GABA in outside-out patches from rat cultured hippocampal neurons. They were blocked by bicuculline and potentiated by diazepam. In 109 of 190 outside-out patches, no channels were active before exposure to GABA (silent patches). The other 81 patches showed spontaneous channel activity. In patches containing spontaneous channel activity, rapid application of GABA rapidly activated channels. In 93 of the silent patches, channels could be activated by GABA but only after a delay that was sometimes as long as 10 minutes. The maximum channel conductance of the channels activated after a delay increased with GABA concentration from less than 10 pS (0.5 microm GABA) to more than 100 pS (10 mm GABA). Fitting the data with a Hill-type equation gave an EC50 value of 33 microm and a Hill coefficient of 0.6. The channels showed outward rectification and were chloride selective. In the presence of 1 microm diazepam, the GABA EC50 decreased to 0.2 microm but the maximum conductance was unchanged. Diazepam decreased the average latency for channel opening. Bicuculline, a GABA antagonist, caused a concentration-dependent decrease in channel conductance. In channels activated with 100 microm GABA the bicuculline IC50 was 19 microm. The effect of GABA on channel conductance shows that the role of the ligand in GABAA receptor channel function is more complex than previously thought.

  • 14.
    Birnir, Bryndis
    et al.
    John Curtin School of Medical Research, Australian National University.
    Eghbali, M
    Everitt, A B
    Gage, P W
    Bicuculline, pentobarbital and diazepam modulate spontaneous GABA(A) channels in rat hippocampal neurons.2000In: British Journal of Pharmacology, ISSN 0007-1188, E-ISSN 1476-5381, Vol. 131, no 4, p. 695-704Article in journal (Refereed)
    Abstract [en]

    Spontaneously opening, chloride-selective channels that showed outward rectification were recorded in ripped-off patches from rat cultured hippocampal neurons and in cell-attached patches from rat hippocampal CA1 pyramidal neurons in slices. In both preparations, channels had multiple conductance states and the most common single-channel conductance varied. In the outside-out patches it ranged from 12 to 70 pS (Vp=40 mV) whereas in the cell-attached patches it ranged from 56 to 85 pS (-Vp=80 mV). Application of GABA to a patch showing spontaneous channel activity evoked a rapid, synchronous activation of channels. During prolonged exposure to either 5 or 100 microM GABA, the open probability of channels decreased. Application of GABA appeared to have no immediate effect on single-channel conductance. Exposure of the patches to 100 microM bicuculline caused a gradual decrease on the single-channel conductance of the spontaneous channels. The time for complete inhibition to take place was slower in the outside-out than in the cell-attached patches. Application of 100 microM pentobarbital or 1 microM diazepam caused 2 - 4 fold increase in the maximum channel conductance of low conductance (<40 pS) spontaneously active channels. The observation of spontaneously opening GABA(A) channels in cell-attached patches on neurons in slices suggests that they may have a role in neurons in vivo and could be an important site of action for some drugs such as benzodiazepines, barbiturates and general anaesthetics.

  • 15.
    Birnir, Bryndis
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Eliasson, L.
    Lund Univ, Dept Clin Sci Malmo, Ctr Diabet, Lund, Sweden..
    She is in science to stay!2018In: Acta Physiologica, ISSN 1748-1708, E-ISSN 1748-1716, Vol. 223, no 1, article id e13048Article in journal (Other academic)
  • 16.
    Birnir, Bryndis
    et al.
    John Curtin School of Medical Research, Australian National University.
    Everitt, A B
    Gage, P W
    Characteristics of GABAA channels in rat dentate gyrus.1994In: Journal of Membrane Biology, ISSN 0022-2631, E-ISSN 1432-1424, Vol. 142, no 1, p. 93-102Article in journal (Refereed)
    Abstract [en]

    Single channel currents were activated by GABA (0.5 to 5 microM) in cell-attached and inside-out patches from cells in the dentate gyrus of rat hippocampal slices. The currents reversed at the chloride equilibrium potential and were blocked by bicuculline (100 microM). Several different kinds of channel were seen: high conductance and low conductance, rectifying and "nonrectifying." Channels had multiple conductance states. The open probability (Po) of channels was greater at depolarized than at hyperpolarized potentials and the relationship between Po and potential could be fitted with a Boltzmann equation with equivalent valency (z) of 1. The combination of outward rectification and potential-dependent open probability gave very little chloride current at hyperpolarized potentials but steeply increasing current with depolarization, useful properties for a tonic inhibitory mechanism.

  • 17.
    Birnir, Bryndis
    et al.
    John Curtin School of Medical Research, Australian National University.
    Everitt, A B
    Lim, M S
    Gage, P W
    Spontaneously opening GABA(A) channels in CA1 pyramidal neurones of rat hippocampus.2000In: Journal of Membrane Biology, ISSN 0022-2631, E-ISSN 1432-1424, Vol. 174, no 1, p. 21-9Article in journal (Refereed)
    Abstract [en]

    Spontaneous, single channel, chloride currents were recorded in 48% of cell-attached patches on neurones in the CA1 region of rat hippocampal slices. In some patches, there was more than 1 channel active. They showed outward rectification: both channel conductance and open probability were greater at depolarized than at hyperpolarized potentials. Channels activated by gamma-aminobutyric acid (GABA) in silent patches on the same neurones had similar conductance and outward rectification. The spontaneous currents were inhibited by bicuculline and potentiated by diazepam. It was concluded that the spontaneously opening channels were constitutively active, nonsynaptic GABA(A) channels. Such spontaneously opening GABA(A) channels may provide a tonic inhibitory mechanism in these cells and perhaps in other cells that have GABA(A) receptors although not having a GABA(A) synaptic input. They may also be a target for clinically useful drugs such as the benzodiazepines.

  • 18.
    Birnir, Bryndis
    et al.
    Lund University, School of Medicine.
    Korpi, Esa R
    The impact of sub-cellular location and intracellular neuronal proteins on properties of GABA(A) receptors.2007In: Current pharmaceutical design, ISSN 1873-4286, Vol. 13, no 31, p. 3169-77Article in journal (Refereed)
    Abstract [en]

    Most studies of GABA(A) receptor accessory proteins have focused on trafficking, clustering and phosphorylation state of the channel-forming subunits and as a result a number of proteins and mechanisms have been identified that can influence the GABA(A) channel expression and function in the cell plasma membrane. In the light of a growing list of intracellular and transmembrane neuronal proteins shown to affect the fate, function and pharmacology of the GABA(A) receptors in neurons, the concept of what constitutes the native GABA(A) receptor complex may need to be re-examined. It is perhaps more appropriate to consider the associated proteins or some of them to be parts of the receptor channel complex in the capacity of ancillary proteins. Here we highlight some of the effects the intracellular environment has on the GABA-activated channel function and pharmacology. The studies demonstrate the need for co-expression of accessory proteins with the GABA(A) channel-forming subunits in heterologous expression systems in order to obtain the full repertoire of GABA(A) receptors characteristics recorded in the native neuronal environment. Further studies e.g. on gene-modified animal models are needed for most of the accessory proteins to establish their significance in normal physiology and in pathophysiology of neurological and psychiatric diseases. The challenge remains to elucidate the effects that the accessory proteins and processes (e.g. phosphorylation) plus the sub-cellular location have on the "fine-tuning" of the functional and pharmacological properties of the GABA(A) receptor channels.

  • 19.
    Birnir, Bryndis
    et al.
    Department of Physiology, UCLA School of Medicine.
    Lee, H S
    Hediger, M A
    Wright, E M
    Expression and characterization of the intestinal Na+/glucose cotransporter in COS-7 cells.1990In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1048, no 1, p. 100-4Article in journal (Refereed)
    Abstract [en]

    Cells derived from the simian kidney, COS-7 cells, were transfected with a eucaryotic expression vector (pEUK-C1) containing the clone for the rabbit intestinal Na+/glucose cotransporter. Expression was monitored after transfection with lipofectin by measuring the initial rate of alpha-methylglucopyranoside (MeGlc) uptake. Cells transfected with vector containing the cDNA for the Na+/glucose cotransporter expressed Na(+)-dependent MeGlc transport. Neither control cells nor cells transfected with vector lacking cloned cDNA expressed the cotransporter. Na(+)-dependent MeGlc uptake into transfected cells was saturable (Km 150 microM), phlorizin-sensitive (Ki 11 microM), and inhibited by sugar analogs (D-glucose greater than MeGlc greater than D-galactose greater than 3-O-methyl-D-glucoside greater than D-allose much greater than L-glucose). Europium was able to mimic Na+ in driving MeGIC uptake. Finally, tunicamycin, an inhibitor of asparagine-linked glycosylation, inhibited the expression of Na(+)-dependent MeGlc transport 80%. We conclude that the rabbit intestinal Na+/glucose cotransporter expressed in COS-7 cell exhibits very similar kinetic properties to that in the native brush border and to that expressed in Xenopus oocytes. In addition, N-linked glycosylation appears to be important for functional expression of this membrane protein.

  • 20.
    Birnir, Bryndis
    et al.
    Department of Physiology, UCLA School of Medicine.
    Loo, D D
    Wright, E M
    Voltage-clamp studies of the Na+/glucose cotransporter cloned from rabbit small intestine.1991In: Pflügers Archiv: European Journal of Physiology, ISSN 0031-6768, E-ISSN 1432-2013, Vol. 418, no 1-2, p. 79-85Article in journal (Refereed)
    Abstract [en]

    Inward Na+ currents associated with the cloned intestinal Na+/glucose cotransporter expressed in Xenopus oocytes have been studied using the two-microelectrode voltage-clamp method. The steady-state current/voltage relations showed voltage-dependent (Vm from +20 to -75 mV) and relatively voltage-independent (Vm from -75 to -150 mV) regions. The apparent Imax for Na+ and glucose increased with negative membrane potentials, and the apparent K0.5 for glucose (K(Glc)0.5) depended on Vm and [Na]o. Increasing [Na]o from 7 to 110 mmol/l had the same effect in decreasing K(Glc)0.5 from 0.44 to 0.03 mmol/l as increasing the Vm from -40 to -150 mV. The I/V curves under saturating conditions (20 mmol/l external sugars and 110 mmol/l [Na]o) were identical for D-glucose, D-galactose, alpha-methyl D-glucopyranoside and 3-O-methyl D-glucoside. The specificity of the cotransporter for sugars was: D-glucose, D-galactose, alpha-methyl D-glucopyranoside greater than 3-O-methyl D-glucoside much greater than D-xylose greater than D-allose much greater than D-mannose. Ki for phlorizin (approximately 10 mumol/l) was independent of Vm at saturating [Na]o. We conclude that a variety of sugars are transported by the cloned Na+/glucose cotransporter at the same maximal rate and that membrane potential affects both the maximal current and the apparent K0.5 of the cotransporter for Na+ and glucose.

  • 21.
    Birnir, Bryndis
    et al.
    John Curtin School of Medical Research, Australian National University.
    Tierney, M L
    Dalziel, J E
    Cox, G B
    Gage, P W
    A structural determinant of desensitization and allosteric regulation by pentobarbitone of the GABAA receptor.1997In: Journal of Membrane Biology, ISSN 0022-2631, E-ISSN 1432-1424, Vol. 155, no 2, p. 157-66Article in journal (Refereed)
    Abstract [en]

    Functional properties of the alpha1beta1 GABAA receptor changes in a subunit-specific manner when a threonine residue in the M2 region at the 12' position was mutated to glutamine. The rate and extent of desensitization increased in all mutants but the rate of activation was faster in the beta1 mutants. A negligible plateau current and abolition of potentiation by pentobarbitone of the GABA-activated current depended on the Thr 12' Gln mutation being present in the beta1 subunit. The Hill coefficient of the peak current response to GABA was reduced to less than one also in a beta1 subunit-specific manner. It was concluded that the beta1 subunit dominated conformational changes activated by GABA.

  • 22.
    Birnir, Bryndis
    et al.
    John Curtin School of Medical Research, Australian National University.
    Tierney, M L
    Howitt, S M
    Cox, G B
    Gage, P W
    A combination of human alpha 1 and beta 1 subunits is required for formation of detectable GABA-activated chloride channels in Sf9 cells.1992In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 250, no 1329, p. 307-12Article in journal (Refereed)
    Abstract [en]

    The baculovirus expression system was used to produce alpha 1 and beta 1 subunits of the human GABAA receptor in Sf9 cells. In cells infected with both alpha 1 and beta 1 recombinant viruses, GABA elicited an outwardly rectifying chloride current that was blocked by bicuculline and potentiated by pentobarbitone. GABA did not produce detectable currents in cells infected with either alpha 1 or beta 1 recombinant viruses alone. In these cells, and in control (non-infected) Sf9 cells, pentobarbitone depressed the leakage current (Ki = 55 microM). Fluorescently labelled monoclonal antibodies to the alpha 1 subunit showed greater amounts of the alpha 1 subunit in cells infected with only the alpha 1 recombinant virus than in cells co-infected with the alpha 1 and beta 1 recombinant viruses. Fluorescence of the plasma membrane was seen in cells co-infected with the alpha 1 and beta 1 recombinant viruses, but was absent in cells infected with only the alpha 1 recombinant virus. It was concluded that the alpha 1 subunit normally interacts with the beta 1 subunit to be transported to the plasma membrane in Sf9 cells.

  • 23.
    Birnir, Bryndis
    et al.
    John Curtin School of Medical Research, Australian National University.
    Tierney, M L
    Lim, M
    Cox, G B
    Gage, P W
    Nature of the 5' residue in the M2 domain affects function of the human alpha 1 beta 1 GABAA receptor.1997In: Synapse, ISSN 0887-4476, E-ISSN 1098-2396, Vol. 26, no 3, p. 324-7Article in journal (Refereed)
    Abstract [en]

    The effects on the functional properties of the alpha 1 beta 1 GABAA receptor when the 5' (alpha 1 Val260; beta 1 Ile255) hydrophobic amino acids in the second transmembrane (M2) region were changed to threonine were examined. In response to a saturating concentration of GABA, the current evoked in mutant receptors showed a decreased rate of desensitization and at equilibrium was a greater fraction of the peak current than in wild-type receptors. The half-saturation concentration of the peak current response to GABA in mutant receptors was comparable to that in wild-type receptors, but the Hill coefficient was reduced to less than one. It was concluded that the 5' amino acids in the M2 region have a role in the conformational changes that occur within the alpha 1 beta 1 GABAA receptor in response to GABA.

  • 24.
    Birnir, Bryndis
    et al.
    John Curtin School of Medical Research, Australian National University.
    Tierney, M L
    Pillai, N P
    Cox, G B
    Gage, P W
    Rapid desensitization of alpha 1 beta 1 GABA A receptors expressed in Sf9 cells under optimized conditions.1995In: Journal of Membrane Biology, ISSN 0022-2631, E-ISSN 1432-1424, Vol. 148, no 2, p. 193-202Article in journal (Refereed)
    Abstract [en]

    alpha 1 and beta 1 subunits of human GABA A receptors were expressed in Sf9 cells using the Sf9-baculovirus system. Better expression was obtained by manipulating the system. Cell growth phase at the time of infection determined the practical range of virus titre, the period postinfection during which cells were useful for signal detection and the maximal current obtained. Cells in the early exponential phase were relatively insensitive to multiplicity of infection (MOI) whereas cells in the mid- to late-exponential phase were highly dependent on MOI and they responded with the largest Cl- current generated by GABA. Channels activated by GABA were chloride-selective. Half the maximum peak whole-cell current was obtained with 11 microM GABA. The time course of Cl- currents activated by saturating GABA concentrations in cells infected with alpha 1 beta 1-recombinant viruses was examined employing a rapid perfusion system which allowed whole-cell solution exchange in less than 1 msec. The current decay could be fitted by 3 to 4 exponentials for the first 8 sec. The initial fast current decrease had a time constant of about 23 msec. No voltage dependence of time constants was detected but the whole-cell IV relation showed outward rectification. Currents were depressed by bicuculline, penicillin and picrotoxin and potentiated by pentobarbitone.

  • 25. Bjurstöm, Helen
    et al.
    Wang, JunYang
    Ericsson, Ida
    Bengtsson, Martin
    Liu, Yawei
    Kumar-Mendu, Suresh
    Lund University, Diabetic Centre, CRC, Department of Clinical Sciences.
    Issazadeh-Navikas, Shohreh
    Birnir, Bryndis
    Lund University, Diabetic Centre, CRC, Department of Clinical Sciences.
    GABA, a natural immunomodulator of T lymphocytes2008In: Journal of Neuroimmunology, ISSN 0165-5728, E-ISSN 1872-8421, Vol. 205, no 1-2, p. 44-50Article in journal (Refereed)
    Abstract [en]

    gamma-aminobutyric acid (GABA) is the main neuroinhibitory transmitter in the brain. Here we show that GABA in the extracellular space may affect the fate of pathogenic T lymphocytes entering the brain. We examined in encephalitogenic T cells if they expressed functional GABA channels that could be activated by the low (nM-1 microM), physiological concentrations of GABA present around neurons in the brain. The cells expressed the alpha1, alpha4, beta2, beta3, gamma1 and delta GABAA channel subunits and formed functional, extrasynaptic-like GABA channels that were activated by 1 microM GABA. 100 nM and higher GABA concentrations decreased T cell proliferation. The results are consistent with GABA being immunomodulatory.

  • 26. Braun, Matthias
    et al.
    Wendt, Anna
    Birnir, Bryndis
    Department of Physiological Sciences, Lund University.
    Broman, Jonas
    Eliasson, Lena
    Galvanovskis, Juris
    Gromada, Jesper
    Mulder, Hindrik
    Rorsman, Patrik
    Regulated exocytosis of GABA-containing synaptic-like microvesicles in pancreatic beta-cells.2004In: The Journal of General Physiology, ISSN 0022-1295, E-ISSN 1540-7748, Vol. 123, no 3, p. 191-204Article in journal (Refereed)
    Abstract [en]

    We have explored whether gamma-aminobutyric acid (GABA) is released by regulated exocytosis of GABA-containing synaptic-like microvesicles (SLMVs) in insulin-releasing rat pancreatic beta-cells. To this end, beta-cells were engineered to express GABA(A)-receptor Cl(-)-channels at high density using adenoviral infection. Electron microscopy indicated that the average diameter of the SLMVs is 90 nm, that every beta-cell contains approximately 3,500 such vesicles, and that insulin-containing large dense core vesicles exclude GABA. Quantal release of GABA, seen as rapidly activating and deactivating Cl(-)-currents, was observed during membrane depolarizations from -70 mV to voltages beyond -40 mV or when Ca(2+) was dialysed into the cell interior. Depolarization-evoked GABA release was suppressed when Ca(2+) entry was inhibited using Cd(2+). Analysis of the kinetics of GABA release revealed that GABA-containing vesicles can be divided into a readily releasable pool and a reserve pool. Simultaneous measurements of GABA release and cell capacitance indicated that exocytosis of SLMVs contributes approximately 1% of the capacitance signal. Mathematical analysis of the release events suggests that every SLMV contains 0.36 amol of GABA. We conclude that there are two parallel pathways of exocytosis in pancreatic beta-cells and that release of GABA may accordingly be temporally and spatially separated from insulin secretion. This provides a basis for paracrine GABAergic signaling within the islet.

  • 27.
    Cocco, Arianna
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Rönnberg, A. M. Carolina
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience.
    Jin, Zhe
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    André, Goncalo Igreja
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience. Univ Western Australia, Ctr Evolutionary Biol, 35 Stirling Hwy, Crawley, WA 6009, Australia..
    Vossen, Laura E.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Bhandage, Amol K.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Thörnqvist, Per-Ove
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Birnir, Bryndis
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Winberg, Svante
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Characterization of the gamma-aminobutyric acid signaling system in the zebrafish (danio rerio hamilton) central nervous system by reverse transcription-quantitative polymerase chain reaction2017In: Neuroscience, ISSN 0306-4522, E-ISSN 1873-7544, Vol. 343, p. 300-321Article in journal (Refereed)
    Abstract [en]

    In the vertebrate brain, inhibition is largely mediated by raminobutyric acid (GABA). This neurotransmitter comprises a signaling machinery of GABA(A), GABA(B) receptors, transporters, glutamate decarboxylases (gads) and 4-aminobutyrate aminotransferase (abat), and associated proteins. Chloride is intimately related to GABAA receptor conductance, GABA uptake, and GADs activity. The response of target neurons to GABA stimuli is shaped by chloride-cation co-transporters (CCCs), which strictly control Cl- gradient across plasma membranes. This research profiled the expression of forty genes involved in GABA signaling in the zebrafish (Danio rerio) brain, grouped brain regions and retinas. Primer pairs were developed for reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The mRNA levels of the zebrafish GABA system share similarities with that of mammals, and confirm previous studies in non-mammalian species. Proposed GABAA receptors are alpha(1)beta(2)gamma(2), alpha(1)beta(2)delta, alpha(2b)beta(3), alpha(2b)beta(3)delta, alpha(4)beta(2)gamma(2), alpha(4)beta(2)gamma, alpha(6b)beta(2)gamma(2) and alpha(6b)beta(2)delta. Regional brain differences were documented. Retinal hetero- or homomeric rho-composed GABAA receptors could exist, accompanying alpha(1)beta(y)gamma(2), alpha(1)beta(y)delta, alpha(6a)beta(y)gamma(2,) alpha(6a)beta(y)delta. Expression patterns of alpha(6a) and alpha(6b) were opposite, with the former being more abundant in retinas, the latter in brains. Given the stoichiometry alpha(6w)beta(y)gamma(z), alpha(6a-) or alpha(6b)-containing receptors likely have different regulatory mechanisms. Different gene isoforms could originate after the rounds of genome duplication during teleost evolution. This research depicts that one isoform is generally more abundantly expressed than the other. Such observations also apply to GABAB receptors, GABA transporters, GABA-related enzymes, CCCs and GABAA receptor associated proteins, whose presence further strengthens the proof of a GABA system in zebrafish.

  • 28. Curmi, J P
    et al.
    Premkumar, L S
    Birnir, Bryndis
    John Curtin School of Medical Research, Australian National University.
    Gage, P W
    The influence of membrane potential on chloride channels activated by GABA in rat cultured hippocampal neurons.1993In: Journal of Membrane Biology, ISSN 0022-2631, E-ISSN 1432-1424, Vol. 136, no 3, p. 273-80Article in journal (Refereed)
    Abstract [en]

    Chloride currents were activated by a low concentration of GABA (0.5 microM) in neonatal rat hippocampal neurons cultured for up to 14 days. Currents elicited by 0.5 microM GABA in neurons, voltage-clamped using the whole-cell technique with pipettes containing 149 mM Cl-, reversed close to 0 mV whether pipettes contained 144 mM Na+ or 140 mM Cs+, and were blocked by 100 microM bicuculline. Current-voltage curves showed outward rectification. Single channel currents appeared in cell-attached patches when the pipette tip was perfused with pipette solution containing 0.5 microM GABA and disappeared when a solution containing 100 microM bicuculline plus 0.5 microM GABA was injected into the pipette tip. The channels showed outward rectification and, in some patches, had a much lower probability of opening at hyperpolarized potentials. The average chord conductance in 10 patches hyperpolarized by 80 mV was 7.8 +/- 1.6 pS (SEM) compared with a chord conductance of 34.1 +/- 3.5 pS (SEM) in the same patches depolarized by 80 mV. Similar single channel currents were also activated in cell-free, inside-out patches in symmetrical chloride solutions when 0.5 microM GABA was injected into the pipette tip. The channels showed outward rectification similar to that seen in cell-attached patches, and some channels had a lower probability of opening at hyperpolarized potentials. The average chord conductance in 13 patches hyperpolarized by 80 mV was 11.8 +/- 2.3 pS (SEM) compared with 42.1 +/- 3.1 pS (SEM) in the same patches depolarized by 80 mV.

  • 29. Dalziel, J E
    et al.
    Birnir, Bryndis
    John Curtin School of Medical Research, Australian National University.
    Everitt, A B
    Tierney, M L
    Cox, G B
    Gage, P W
    A threonine residue in the M2 region of the beta1 subunit is needed for expression of functional alpha1beta1 GABA(A) receptors.1999In: European Journal of Pharmacology, ISSN 0014-2999, E-ISSN 1879-0712, Vol. 370, no 3, p. 345-8Article in journal (Refereed)
    Abstract [en]

    Although there is a high degree of homology in the M2 transmembrane segments of alpha1 and beta1 subunits, subunit-specific effects were observed in alpha1beta1 GABA(A) receptors expressed in Spodoptera frugipedra (Sf9) cells when the conserved 13' threonine residue in the M2 transmembrane region was mutated to alanine. When threonine 263 (13') was mutated to alanine in the beta1 subunit, high-affinity muscimol binding and the response to GABA were abolished. This did not occur when the threonine 263 (13') was mutated to alanine in the alpha1 subunit, but the rate of desensitisation increased and the effect of bicuculline, a competitive inhibitor, was reduced. The results show differential effects of subunits on receptor function and support a role for M2 in desensitisation.

  • 30. Dalziel, J E
    et al.
    Cox, G B
    Gage, P W
    Birnir, Bryndis
    John Curtin School of Medical Research, Australian National University.
    Mutant human alpha(1)beta(1)(T262Q) GABA(A) receptors are directly activated but not modulated by pentobarbital.1999In: European Journal of Pharmacology, ISSN 0014-2999, E-ISSN 1879-0712, Vol. 385, no 2-3, p. 283-6Article in journal (Refereed)
    Abstract [en]

    Pentobarbital activates GABA(A) receptors and enhances GABA-activated currents. A threonine residue (262) in the second membrane spanning region at the 12' position in the beta(1) subunit, alpha(1)beta(1)(T12'Q), is necessary for the potentiating action of pentobarbital. We examined whether T12'Q-mutated receptors expressed in Spodoptera frugipedra (Sf 9) cells responded to direct activation by pentobarbital. In both mutant and wild type receptors, pentobarbital (100 microM to 1 mM) evoked a current response. The pentobarbital EC(50) values were similar; 119 and 158 microM for alpha(1)beta(1) and alpha(1)beta(1)(T12'Q) receptors, respectively. The results show it is possible to discriminate between agonistic and potentiating effects of pentobarbital, suggesting these actions involve separate mechanisms.

  • 31. Dalziel, J E
    et al.
    Cox, G B
    Gage, P W
    Birnir, Bryndis
    John Curtin School of Medical Research, Australian National University.
    Mutating the highly conserved second membrane-spanning region 9' leucine residue in the alpha(1) or beta(1) subunit produces subunit-specific changes in the function of human alpha(1)beta(1) gamma-aminobutyric Acid(A) receptors.2000In: Molecular Pharmacology, ISSN 0026-895X, E-ISSN 1521-0111, Vol. 57, no 5, p. 875-82Article in journal (Refereed)
    Abstract [en]

    The properties of the human alpha(1)beta(1) gamma-aminobutyric acid (GABA)(A) receptors were investigated after mutation of a highly conserved leucine residue at the 9' position in the second membrane-spanning region (TM2). The role of this residue in alpha(1) and beta(1) subunits was examined by mutating the 9' leucine to phenylalanine, tyrosine, or alanine. The mutations were in either the alpha(1) subunit (alpha*beta), the beta(1) subunit (alphabeta*), or in both subunits (alpha*beta*), and the receptors were expressed in Sf9 cells. Our results show that the rate of desensitization is increased as the size and hydrophobicity of the 9' residue in the alpha(1) subunit is increased: Y, F > L > A, T. Mutation of L9' in only the beta(1) subunit (alphabeta*) to either phenylalanine or tyrosine increased the EC(50) value for GABA at least 100 times, but the EC(50) was unchanged in alphabeta* alanine mutants. In the 9' alpha(1) mutants (alpha*beta, alpha*beta*) the GABA EC(50) was minimally affected. In alpha*beta and alpha*beta*, but not alphabeta*, the peak currents evoked by millimolar concentrations of GABA were greatly reduced. The reduction in currents could only be partially accounted for by decreased expression of the receptors These findings suggest different roles for the two types of subunits in GABA activation and later desensitization of alpha(1)beta(1) receptors. In addition, an increase in the resting membrane conductance was recorded in alanine but not in phenylalanine and tyrosine mutants, indicating that the side chain size at the 9' position is a major determinant of current flow in the closed conformation.

  • 32. Eghbali, M
    et al.
    Curmi, J P
    Birnir, Bryndis
    John Curtin School of Medical Research, Australian National University.
    Gage, P W
    Hippocampal GABA(A) channel conductance increased by diazepam.1997In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 388, no 6637, p. 71-5Article in journal (Refereed)
    Abstract [en]

    Benzodiazepines, which are widely used clinically for relief of anxiety and for sedation, are thought to enhance synaptic inhibition in the central nervous system by increasing the open probability of chloride channels activated by the inhibitory neurotransmitter gamma-aminobutyric acid (GABA). Here we show that the benzodiazepine diazepam can also increase the conductance of GABAA channels activated by low concentrations of GABA (0.5 or 5 microM) in rat cultured hippocampal neurons. Before exposure to diazepam, chloride channels activated by GABA had conductances of 8 to 53pS. Diazepam caused a concentration-dependent and reversible increase in the conductance of these channels towards a maximum conductance of 70-80 pS and the effect was as great as 7-fold in channels of lowest initial conductance. Increasing the conductance of GABAA channels tonically activated by low ambient concentrations of GABA in the extracellular environment may be an important way in which these drugs depress excitation in the central nervous system. That any drug has such a large effect on single channel conductance has not been reported previously and has implications for models of channel structure and conductance.

  • 33. Eghbali, M
    et al.
    Gage, P W
    Birnir, Bryndis
    Department of Physiology and Anesthesiology, UCLA School of Medicine.
    Pentobarbital modulates gamma-aminobutyric acid-activated single-channel conductance in rat cultured hippocampal neurons.2000In: Molecular Pharmacology, ISSN 0026-895X, E-ISSN 1521-0111, Vol. 58, no 3, p. 463-9Article in journal (Refereed)
    Abstract [en]

    We examined the effect of a range of pentobarbital concentrations on 0.5 microM gamma-aminobutyric acid (GABA)-activated channels (10 +/- 1 pS) in inside-out or outside-out patches from rat cultured hippocampal neurons. The conductance increased from 12 +/- 4 to 62 +/- 9 pS as the pentobarbital concentration was raised from 10 to 500 microM and the data could be fitted by a Hill-type equation. At 100 microM pentobarbital plus 0.5 microM GABA, the conductance seemed to reach a plateau. The pentobarbital EC(50)(0.5 microM GABA) value was 22 +/- 4 microM and n was 1.9 +/- 0.5. In 1 mM pentobarbital plus 0.5 microM GABA, the single-channel conductance decreased to 34 +/- 8 pS. This apparent inhibition of channel conductance was relieved by 1 microM diazepam. The channel conductance was 64 +/- 6 pS in the presence of all three drugs. The channels were open more in the presence of both GABA and pentobarbital than in the presence of either drug alone. Pentobarbital alone (100 microM) activated channels with conductance (30 +/- 2 pS) and kinetic properties distinct from those activated by either GABA alone or GABA plus pentobarbital. Whether pentobarbital induces new conformations or promotes conformations observed in the presence of GABA alone cannot be determined from our study, but the results clearly show that it is the combination of drugs present that determines the single-channel conductance and the kinetic properties of the receptors.

  • 34. Eghbali, Mansoureh
    et al.
    Birnir, Bryndis
    Division of Molecular Bioscience, John Curtin School of Medical Research, Australian National University.
    Gage, Peter W
    Conductance of GABAA channels activated by pentobarbitone in hippocampal neurons from newborn rats.2003In: Journal of Physiology, ISSN 0022-3751, E-ISSN 1469-7793, Vol. 552, no Pt 1, p. 13-22Article in journal (Refereed)
    Abstract [en]

    Neurons were obtained from the CA1 region of the hippocampus of newborn rats and maintained in culture. Channels were activated by pentobarbitone in cell-attached, inside-out or outside-out patches, normally by applying pentobarbitone in flowing bath solution. Currents were outwardly rectifying and blocked by bicuculline, properties of GABAA channels in these cells. Maximum channel conductance increased as pentobarbitone concentration was increased to 500 microM but conductance then decreased as pentobarbitone concentration was raised further. The best fit of a Hill-type equation to the relationship between maximum channel conductance and pentobarbitone concentration (up to 500 microM) gave an EC50 of 41 microM, a maximum conductance of 36 pS and a Hill coefficient of 1.6. Bicuculline decreased the maximum conductance of the channels activated by pentobarbitone, with an IC50 of 224 microM. Diazepam increased channel conductance, with a maximum effect being obtained with 1 microM diazepam. Diazepam (1 microM) decreased the EC50 of the pentobarbitone effect on channel conductance from 41 microM to 7.2 microM and increased maximum conductance to 72 pS. We conclude that GABAA channel conductance is related to the concentration of the allosteric agonist pentobarbitone.

  • 35. Eghbali, Mansoureh
    et al.
    Gage, Peter W
    Birnir, Bryndis
    John Curtin School of Medical Research, Australian National University.
    Effects of propofol on GABAA channel conductance in rat-cultured hippocampal neurons.2003In: European Journal of Pharmacology, ISSN 0014-2999, E-ISSN 1879-0712, Vol. 468, no 2, p. 75-82Article in journal (Refereed)
    Abstract [en]

    Channels were activated, in ripped-off patches from rat-cultured hippocampal neurons, by propofol alone, propofol plus 0.5 microM GABA (gamma-aminobutyric acid) or GABA alone. The propofol-activated currents were chloride-selective, showed outward-rectification and were enhanced by 1 microM diazepam. The maximum propofol-activated channel conductance increased with propofol concentration from less than 15 pS (10 microM) to about 60 pS (500 microM) but decreased to 40 pS in 1 mM propofol. Fitting the data from 10 to 500 microM propofol with a Hill-type equation gave a maximum conductance of 64 pS, an EC50 value of 32 microM and a Hill coefficient of 1.1. Addition of 0.5 microM GABA shifted the propofol EC50 value to 10 microM and increased the maximum channel conductance to about 100 pS. The Hill coefficient was 0.8. The maximum channel conductance did not increase further when 1 microM diazepam was added together with a saturating propofol concentration and GABA. The results are compared to effects other drugs have on GABAA channels conductance.

  • 36. Everitt, Andrea B
    et al.
    Luu, Tien
    Cromer, Brett
    Tierney, M Louise
    Birnir, Bryndis
    Division of Molecular Bioscience, John Curtin School of Medical Research, Australian National University.
    Olsen, Richard W
    Gage, Peter W
    Conductance of recombinant GABA (A) channels is increased in cells co-expressing GABA(A) receptor-associated protein.2004In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 279, no 21, p. 21701-6Article in journal (Refereed)
    Abstract [en]

    High conductance gamma-aminobutyric acid type A (GABA(A)) channels (>40 picosiemens (pS)) have been reported in some studies on GABA(A) channels in situ but not in others, whereas recombinant GABA(A) channels do not appear to display conductances above 40 pS. Furthermore, the conductance of some native GABA(A) channels can be increased by diazepam or pentobarbital, which are effects not reported for expressed GABA(A) channels. GABARAP, a protein associated with native GABA(A) channels, has been reported to cause clustering of GABA(A) receptors and changes in channel kinetics. We have recorded single channel currents activated by GABA in L929 cells expressing alpha(1), beta(1), and gamma(2S) subunits of human GABA(A) receptors. Channel conductance was never higher than 40 pS and was not significantly increased by diazepam or pentobarbital, although open probability was increased. In contrast, in cells expressing the same three subunits together with GABARAP, channel conductance could be significantly higher than 40 pS, and channel conductance was increased by diazepam and pentobarbital. GABARAP caused clustering of receptors in L929 cells, and we suggest that there may be interactions between subunits of clustered GABA(A) receptors that make them open co-operatively to give high conductance "channels." Recombinant channels may require the influence of GABARAP and perhaps other intracellular proteins to adopt a fuller repertoire of properties of native channels.

  • 37. Fellerhoff-Losch, Barbara
    et al.
    Korol, Sergiy V.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Ganor, Yonatan
    Gu, Songhai
    Cooper, Itzik
    Eilam, Raya
    Besser, Michal
    Goldfinger, Meidan
    Chowers, Yehuda
    Wank, Rudolf
    Birnir, Bryndis
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Levite, Mia
    Normal human CD4+ helper T cells express Kv1.1 voltage-gated K+ channels, and selective Kv1.1 block in T cells induces by itself robust TNFα production and secretion and activation of the NFκB non-canonical pathway2016In: Journal of neural transmission, ISSN 0300-9564, E-ISSN 1435-1463, Vol. 123, no 3, p. 137-157Article in journal (Refereed)
    Abstract [en]

    TNFα is a very potent and pleiotropic pro-inflammatory cytokine, essential to the immune system for eradicating cancer and microorganisms, and to the nervous system, for brain development and ongoing function. Yet, excess and/or chronic TNFα secretion causes massive tissue damage in autoimmune, inflammatory and neurological diseases and injuries. Therefore, many patients with autoimmune/inflammatory diseases receive anti-TNFα medications. TNFα is secreted primarily by CD4+ T cells, macrophages, monocytes, neutrophils and NK cells, mainly after immune stimulation. Yet, the cause for the pathologically high and chronic TNFα secretion is unknown. Can blocking of a particular ion channel in T cells induce by itself TNFα secretion? Such phenomenon was never revealed or even hypothesized. In this interdisciplinary study we discovered that: (1) normal human T cells express Kv1.1 voltage-gated potassium channel mRNA, and the Kv1.1 membrane-anchored protein channel; (2) Kv1.1 is expressed in most CD4+CD3+ helper T cells (mean CD4+CD3+Kv1.1+ T cells of 7 healthy subjects: 53.09 ± 22.17 %), but not in CD8+CD3+ cytotoxic T cells (mean CD8+CD3+Kv1.1+ T cells: 4.12 ± 3.04 %); (3) electrophysiological whole-cell recordings in normal human T cells revealed Kv currents; (4) Dendrotoxin-K (DTX-K), a highly selective Kv1.1 blocker derived from snake toxin, increases the rate of rise and decay of Kv currents in both resting and activated T cells, without affecting the peak current; (5) DTX-K by itself induces robust TNFα production and secretion by normal human T cells, without elevating IFNγ, IL-4 and IL-10; (6) intact Ca2+ channels are required for DTX-induced TNFα secretion; (7) selective anti-Kv1.1 antibodies also induce by themselves TNFα secretion; (8) DTX-K activates NFκB in normal human T cells via the unique non-canonical-pathway; (9) injection of Kv1.1-blocked human T cells to SCID mice, causes recruitment of resident mouse cells into the liver, alike reported after TNFα injection into the brain. Based on our discoveries we speculate that abnormally blocked Kv1.1 in T cells (and other immune cells?), due to either anti-Kv1.1 autoimmune antibodies, or Kv1.1-blocking toxins alike DTX-K, or Kv1.1-blocking genetic mutations, may be responsible for the chronic/excessive TNFα in autoimmune/inflammatory diseases. Independently, we also hypothesize that selective block of Kv1.1 in CD4+ T cells of patients with cancer or chronic infectious diseases could be therapeutic, since it may: a. augment beneficial secretion and delivery of TNFα to the disease-affected sites; b. induce recruitment and extravasation of curative immune cells and factors; c. improve accessibility of drugs to the brain and few peripheral organs thanks to TNFα-induced increased permeability of organ’s barriers.

  • 38. Fuks, Jonas M
    et al.
    Arrighi, Romanico B G
    Weidner, Jessica M
    Kumar Mendu, Suresh
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience.
    Jin, Zhe
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Wallin, Robert P A
    Rethi, Bence
    Birnir, Bryndis
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Barragan, Antonio
    GABAergic Signaling Is Linked to a Hypermigratory Phenotype in Dendritic Cells Infected by Toxoplasma gondii2012In: PLoS pathogens, ISSN 1553-7374, Vol. 8, no 12, p. e1003051-Article in journal (Refereed)
    Abstract [en]

    During acute infection in human and animal hosts, the obligate intracellular protozoan Toxoplasma gondii infects a variety of cell types, including leukocytes. Poised to respond to invading pathogens, dendritic cells (DC) may also be exploited by T. gondii for spread in the infected host. Here, we report that human and mouse myeloid DC possess functional γ-aminobutyric acid (GABA) receptors and the machinery for GABA biosynthesis and secretion. Shortly after T. gondii infection (genotypes I, II and III), DC responded with enhanced GABA secretion in vitro. We demonstrate that GABA activates GABA(A) receptor-mediated currents in T. gondii-infected DC, which exhibit a hypermigratory phenotype. Inhibition of GABA synthesis, transportation or GABA(A) receptor blockade in T. gondii-infected DC resulted in impaired transmigration capacity, motility and chemotactic response to CCL19 in vitro. Moreover, exogenous GABA or supernatant from infected DC restored the migration of infected DC in vitro. In a mouse model of toxoplasmosis, adoptive transfer of infected DC pre-treated with GABAergic inhibitors reduced parasite dissemination and parasite loads in target organs, e.g. the central nervous system. Altogether, we provide evidence that GABAergic signaling modulates the migratory properties of DC and that T. gondii likely makes use of this pathway for dissemination. The findings unveil that GABA, the principal inhibitory neurotransmitter in the brain, has activation functions in the immune system that may be hijacked by intracellular pathogens.

  • 39.
    Jin, Yang
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Korol, Sergiy
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Jin, Zhe
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Laver, Derek
    University of Newcastle.
    Birnir, Bryndis
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    In a cell-type specific manner, high-affinity GABA-A receptors participate in autocrine and paracrine GABA signaling in human pancreatic isletsManuscript (preprint) (Other academic)
    Abstract [en]

    γ-Aminobutyric acid (GABA), best known as the classical inhibitory neurotransmitter, is also produced and released by pancreatic islet cells. The hormone secreting α, β and δ- cells in human islets express GABA-A receptors that are activated by GABA. GABA signaling in the islets is thought to regulate hormone secretion but how it comes about is unclear. To-date the interstitial GABA concentration and cell-type specific GABA-A receptors have not been characterized. As a consequence, it is not clear how the interstitial GABA in the intact human islet regulates the specific cell-types. We have set- up single-cell RT-PCR combined whole-cell patch-clamp to investigate the functional role of GABA-A receptors in identified cell within intact human islets. GABA-activated tonic current is present in all α, β and δ-cells whereas only the δ-cells respond to GABA with large, transient currents. High-affinity GABA-A receptors activated with interstitial concentrations lower than 10 nM GABA are expressed in both α and β-cells. In the β- cells different subtypes of GABA-A receptors were identified based on single-channel kinetics, current-voltage relation and pharmacology. The data provides insight into the mechanisms underlying GABA regulation of different cell-types in intact human islet.

  • 40.
    Jin, Yang
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Korol, Sergiy V
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Jin, Zhe
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Barg, Sebastian
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Birnir, Bryndis
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    In Intact Islets Interstitial GABA Activates GABA(A) Receptors That Generate Tonic Currents in alpha-Cells2013In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 6, p. e67228-Article in journal (Refereed)
    Abstract [en]

    In the rat islets γ-aminobutyric acid (GABA) is produced by the β-cells and, at least, the α-cells express the GABAA receptors (GABAA channels). In this study, we examined in intact islets if the interstitial GABA activated the GABAA receptors. We used the patch-clamp technique to record whole-cell and single-channel currents and single-cell RT-PCR to identify the cell-type we recorded from, in the intact rat islets. We further identified which GABAA receptor subunits were expressed. We determined the cell-type of 43 cells we recorded from and of these 49%, 28% and 7% were α, β and δ-cells, respectively. In the remaining 16% of the cells, mRNA transcripts of more than one hormone gene were detected. The results show that in rat islets interstitial GABA activates tonic current in the α-cells but not in the β-cells. Seventeen different GABAA receptor subunits are expressed with high expression of α1, α2, α4, α6, β3, γ1, δ, ρ1, ρ2 and ρ3 subunits whereas no expression was detected for α5 or ε subunits. The abundance of the GABAA receptor subunits detected suggests that a number of GABAA receptor subtypes are formed in the islets. The single-channel and tonic currents were enhanced by pentobarbital and inhibited by the GABAA receptor antagonist SR-95531. The single-channel conductance ranged from 24 to 105 pS. Whether the single-channel conductance is related to subtypes of the GABAA receptor or variable interstitial GABA concentrations remains to be determined. Our results reveal that GABA is an extracellular signaling molecule in rat pancreatic islets and reaches concentration levels that activate GABAA receptors on the glucagon-releasing α-cells.

  • 41.
    Jin, Zhe
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Bazov, Igor
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Kononenko, Olga
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Korpi, Esa R
    Univ Helsinki, Inst Biomed, FIN-00014 Helsinki, Finland.
    Bakalkin, Georgy
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Birnir, Bryndis
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Selective Changes of GABA(A) Channel Subunit mRNAs in the Hippocampus and Orbitofrontal Cortex but not in Prefrontal Cortex of Human Alcoholics2012In: Frontiers in Cellular Neuroscience, ISSN 1662-5102, E-ISSN 1662-5102, Vol. 5, article id 30Article in journal (Refereed)
    Abstract [en]

    Alcohol dependence is a common chronic relapsing disorder. The development of alcohol dependence has been associated with changes in brain GABA(A) channel-mediated neurotransmission and plasticity. We have examined mRNA expression of the GABA(A) channel subunit genes in three brain regions in individuals with or without alcohol dependence using quantitative real-time PCR assay. The levels of selective GABA(A) channel subunit mRNAs were altered in specific brain regions in alcoholic subjects. Significant increase in the α1, α4, α5, β1, and γ1 subunit mRNAs in the hippocampal dentate gyrus region, and decrease in the β2 and δ subunit mRNAs in the orbitofrontal cortex were identified whereas no changes in the dorsolateral prefrontal cortex were detected. The data increase our understanding of the role of GABA(A) channels in the development of alcohol dependence.

  • 42.
    Jin, Zhe
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Bhandage, Amol K.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Bazov, Igor
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Kononenko, Olga
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Bakalkin, Georgy
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Korpi, Esa R.
    Birnir, Bryndis
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Expression of specific ionotropic glutamate and GABA-A receptor subunits is decreased in central amygdala of alcoholics2014In: Frontiers in Cellular Neuroscience, ISSN 1662-5102, E-ISSN 1662-5102, Vol. 8, p. 288-Article in journal (Refereed)
    Abstract [en]

    The central amygdala (CeA) has a role for mediating fear and anxiety responses. It is also involved in emotional imbalance caused by alcohol abuse and dependence and in regulating relapse to alcohol abuse. Growing evidences suggest that excitatory glutamatergic and inhibitory gamma-aminobutyric acid-ergic (GABAergic) transmissions in the CeA are affected by chronic alcohol exposure. Human post-mortem CeA samples from male alcoholics (n = 9) and matched controls (n = 9) were assayed for the expression level of ionotropic glutamate and GABA-A receptors subunit mRNAs using quantitative real-time reverse transcription-PCB (RT-qPCR). Our data revealed that out of the 16 ionotropic glutamate receptor subunits, mRNAs encoding two AMPA P-amino-3-(3-hydroxy-5-methyl-isoxazol-4-y1)propanoic acid] receptor subunits GluA1 and GluA4; one kainate receptor subunit GluK2; one NMDA (N-methyl-D-aspartate) receptor subunit GluN2D and one delta receptor subunit GluD2 were significantly decreased in the CeA of alcoholics. In contrast, of the 19 GABA-A receptor subunits, only the mRNA encoding the a2 subunit was significantly down-regulated in the CeA of the alcoholics as compared with control subjects. Our findings imply that the down-regulation of specific ionotropic glutamate and GABA-A receptor subunits in the CeA of alcoholics may represent one of the molecular substrates underlying the new balance between excitatory and inhibitory neurotransmission in alcohol dependence.

  • 43.
    Jin, Zhe
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Bhandage, Amol K
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Bazov, Igor
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Kononenko, Olga
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Bakalkin, Georgy
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Korpi, Esa R
    Birnir, Bryndis
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Selective increases of AMPA, NMDA, and kainate receptor subunit mRNAs in the hippocampus and orbitofrontal cortex but not in prefrontal cortex of human alcoholics2014In: Frontiers in Cellular Neuroscience, ISSN 1662-5102, E-ISSN 1662-5102, Vol. 8, p. 11-Article in journal (Refereed)
    Abstract [en]

    Glutamate is the main excitatory transmitter in the human brain. Drugs that affect the glutamatergic signaling will alter neuronal excitability. Ethanol inhibits glutamate receptors. We examined the expression level of glutamate receptor subunit mRNAs in human post-mortem samples from alcoholics and compared the results to brain samples from control subjects. RNA from hippocampal dentate gyrus (HP-DG), orbitofrontal cortex (OFC), and dorso-lateral prefrontal cortex (DL-PFC) samples from 21 controls and 19 individuals with chronic alcohol dependence were included in the study. Total RNA was assayed using quantitative RT-PCR. Out of the 16 glutamate receptor subunits, mRNAs encoding two AMPA [2-amino-3-(3-hydroxy-5-methyl-isoxazol-4-yl)propanoic acid] receptor subunits GluA2 and GluA3; three kainate receptor subunits GluK2, GluK3 and GluK5 and five NMDA (N-methyl-D-aspartate) receptor subunits GluN1, GluN2A, GluN2C, GluN2D, and GluN3A were significantly increased in the HP-DG region in alcoholics. In the OFC, mRNA encoding the NMDA receptor subunit GluN3A was increased, whereas in the DL-PFC, no differences in mRNA levels were observed. Our laboratory has previously shown that the expression of genes encoding inhibitory GABA-A receptors is altered in the HP-DG and OFC of alcoholics (Jin et al., 2011). Whether the changes in one neurotransmitter system drives changes in the other or if they change independently is currently not known. The results demonstrate that excessive long-term alcohol consumption is associated with altered expression of genes encoding glutamate receptors in a brain region-specific manner. It is an intriguing possibility that genetic predisposition to alcoholism may contribute to these gene expression changes.

  • 44.
    Jin, Zhe
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Jin, Yang
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Birnir, Bryndis
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    GABA-activated single-channel and tonic currents in rat brain slices2011In: Journal of Visualized Experiments, ISSN 1940-087X, E-ISSN 1940-087X, no 53Article in journal (Refereed)
    Abstract [en]

    The GABA(A) channels are present in all neurons and are located both at synapses and outside of synapses where they generate phasic and tonic currents, respectively. The GABA(A) channel is a pentameric GABA-gated chloride channel. The channel subunits are grouped into 8 families (α1-6, β1-3, γ1-3, δ, ε, θ, π and ρ). Two alphas, two betas and one 3(rd) subunit form the functional channel. By combining studies of sub-type specific GABA-activated single-channel molecules with studies including all populations of GABA(A) channels in the neuron it becomes possible to understand the basic mechanism of neuronal inhibition and how it is modulated by pharmacological agents. We use the patch-clamp technique to study the functional properties of the GABA(A) channels in alive neurons in hippocampal brain slices and record the single-channel and whole-cell currents. We further examine how the channels are affected by different GABA concentrations, other drugs and intra and extracellular factors. For detailed theoretical and practical description of the patch-clamp method please see The Single-Channel Recordings edited by B Sakman and E Neher.

  • 45.
    Jin, Zhe
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Jin, Yang
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Kumar-Mendu, Suresh
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Degerman, Eva
    Groop, Leif
    Birnir, Bryndis
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Insulin reduces neuronal excitability by turning on GABA(A) channels that generate tonic current2011In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 6, no 1, p. e16188-Article in journal (Refereed)
    Abstract [en]

    Insulin signaling to the brain is important not only for metabolic homeostasis but also for higher brain functions such as cognition. GABA (γ-aminobutyric acid) decreases neuronal excitability by activating GABA(A) channels that generate phasic and tonic currents. The level of tonic inhibition in neurons varies. In the hippocampus, interneurons and dentate gyrus granule cells normally have significant tonic currents under basal conditions in contrast to the CA1 pyramidal neurons where it is minimal. Here we show in acute rat hippocampal slices that insulin (1 nM) "turns on" new extrasynaptic GABA(A) channels in CA1 pyramidal neurons resulting in decreased frequency of action potential firing. The channels are activated by more than million times lower GABA concentrations than synaptic channels, generate tonic currents and show outward rectification. The single-channel current amplitude is related to the GABA concentration resulting in a single-channel GABA affinity (EC(50)) in intact CA1 neurons of 17 pM with the maximal current amplitude reached with 1 nM GABA. They are inhibited by GABA(A) antagonists but have novel pharmacology as the benzodiazepine flumazenil and zolpidem are inverse agonists. The results show that tonic rather than synaptic conductances regulate basal neuronal excitability when significant tonic conductance is expressed and demonstrate an unexpected hormonal control of the inhibitory channel subtypes and excitability of hippocampal neurons. The insulin-induced new channels provide a specific target for rescuing cognition in health and disease.

  • 46.
    Jin, Zhe
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Korol, Sergiy V.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Birnir, Bryndis
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Insulin modulates GABA(A) receptor-mediated inhibition in rat amygdala neurons2014In: Acta Physiologica, ISSN 1748-1708, E-ISSN 1748-1716, Vol. 211, no S696, p. 83-83, article id P39Article in journal (Other academic)
  • 47.
    Jin, Zhe
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Korol, Sergiy V.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Jin, Yang
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Birnir, Bryndis
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Insulin modulates GABAA receptor-mediated neuronal inhibition in rat hippocampus and amygdala2015In: Acta Physiologica, ISSN 1748-1708, E-ISSN 1748-1716, Vol. 215, p. 90-90Article in journal (Other academic)
  • 48.
    Jin, Zhe
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Mendu, Suresh Kumar
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Bhandage, Amol K.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Birnir, Bryndis
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    GABA is an efficient immunomodulator molecule2012In: Nerve-Driven Immunity: Neurotransmitters and Neuropeptides in the Immune System / [ed] Mia Levite, Wien: Springer, 2012, 1st, p. 163-173Chapter in book (Refereed)
  • 49.
    Jin, Zhe
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Neurology.
    Mendu, Suresh Kumar
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Birnir, Bryndis
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    GABA is an effective immunomodulatory molecule2013In: Amino Acids, ISSN 0939-4451, E-ISSN 1438-2199, Vol. 45, no 1, p. 87-94Article in journal (Refereed)
    Abstract [en]

    In recent years, it has become clear that there is an extensive cross-talk between the nervous and the immune system. Somewhat surprisingly, the immune cells themselves do express components of the neuronal neurotransmitters systems. What role the neurotransmitters, their ion channels, receptors and transporters have in immune function and regulation is an emerging field of study. Several recent studies have shown that the immune system is capable of synthesizing and releasing the classical neurotransmitter GABA (γ-aminobutyric acid). GABA has a number of effects on the immune cells such as activation or suppression of cytokine secretion, modification of cell proliferation and GABA can even affect migration of the cells. The immune cells encounter GABA when released by the immune cells themselves or when the immune cells enter the brain. In addition, GABA can also be found in tissues like the lymph nodes, the islets of Langerhans and GABA is in high enough concentration in blood to activate, e.g., GABA-A channels. GABA appears to have a role in autoimmune diseases like multiple sclerosis, type 1 diabetes, and rheumatoid arthritis and may modulate the immune response to infections. In the near future, it will be important to work out what specific effects GABA has on the function of the different types of immune cells and determine the underlying mechanisms. In this review, we discuss some of the recent findings revealing the role of GABA as an immunomodulator.

  • 50.
    Korol, Sergiy V.
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Jin, Zhe
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Babateen, Omar
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Birnir, Bryndis
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    GLP-1 and Exendin-4 Transiently Enhance GABA(A) Receptor-Mediated Synaptic and Tonic Currents in Rat Hippocampal CA3 Pyramidal Neurons2015In: Diabetes, ISSN 0012-1797, E-ISSN 1939-327X, Vol. 64, no 1, p. 79-89Article in journal (Refereed)
    Abstract [en]

    GLP-1 is a hormone that stimulates insulin secretion. Receptors for GLP-1 are also found in the brain, including the hippocampus, the centre for memory and learning. Diabetes mellitus is a risk factor for decreased memory functions. We studied effects of GLP-1 and exendin-4, a GLP-1 receptor agonist, on γ-aminobutyric acid (GABA) signaling in hippocampal CA3 pyramidal neurons. GABA is the main inhibitory neurotransmitter and decreases neuronal excitability. GLP-1 (0.01 – 1 nmol/L) transiently enhanced synaptic and tonic currents and the effects were blocked by exendin(9–39). Ten pmol/L GLP-1 increased both the spontaneous inhibitory postsynaptic current (sIPSC) amplitudes and frequency by a factor of 1.8. In 0.1, 1 nmol/L GLP-1 or 10, 50 or 100 nmol/L exendin-4, only the sIPSC frequency increased. The tonic current was enhanced by 0.01 – 1 nmol/L GLP-1 and by 0.5 – 100 nmol/L exendin-4. When action potentials were inhibited by tetrodotoxin (TTX), IPSCs decreased and currents were no longer potentiated by GLP-1 or exendin-4. In contrast, although the tonic current decreased in TTX, it was still enhanced by GLP-1 or exendin-4. The results demonstrate GLP-1 receptor regulation of hippocampal function and are consistent with GLP-1 receptor agonists enhancing GABAA signaling by pre- and postsynaptic mechanisms.

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