GLP-1 and Exendin-4 Transiently Enhance GABA(A) Receptor-Mediated Synaptic and Tonic Currents in Rat Hippocampal CA3 Pyramidal Neurons
2015 (English)In: Diabetes, ISSN 0012-1797, E-ISSN 1939-327X, Vol. 64, no 1, 79-89 p.Article in journal (Refereed) Published
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.
Place, publisher, year, edition, pages
2015. Vol. 64, no 1, 79-89 p.
Public Health, Global Health, Social Medicine and Epidemiology
IdentifiersURN: urn:nbn:se:uu:diva-234954DOI: 10.2337/db14-0668ISI: 000346765600010OAI: oai:DiVA.org:uu-234954DiVA: diva2:758486