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Background and aims: Abdominal aortic aneurysm (AAA) is a vascular disease characterized by the progressive dilation of the aorta, culminating in rupture. At present, there are no pharmacological treatments to prevent AAA development or reduce rupture rate. A recent study showed that patients prescribed Glucagon-like peptide-1 receptor agonists (GLP-1RAs) have significantly lower risks of mortality, AAA repair, and acute abdominal aortic syndrome. Semaglutide is a GLP-1RA with increased agonist capacity and longer half-life, compared to earlier generations of GLP-1RAs. In this study, we aimed to investigate the role and mechanisms of semaglutide in the prevention of AAA development and rupture in a murine model.

Methods: AAA was induced in apolipoprotein-E-deficient mice, by continuous subcutaneous infusion of angiotensin II. Treatment with semaglutide (12 µg/kg) began seven days after disease induction (rescue trial) or simultaneously with disease induction (prophylactic trial). At experimental endpoint, aortic diameter was measured by high-frequency ultrasound and the aortic tissue was collected for histological analysis.

Results: Prophylactic treatment with semaglutide drastically reduced mortality by dissection and rupture during the first seven days of disease development, but did not affect AAA formation at 28 days. Histological evaluation of the aorta at day seven showed a normal vessel wall thickness with a trend for a higher content of collagen in the aortic wall in mice treated with semaglutide, compared to controls.

Conclusions: Semaglutide prevents aortic rupture and dissection in the early phases of AAA development in the angiotensin II mouse model, likely by promoting the maintenance of an adequate proportion of collagen in the vessel wall.

Lipid systems play a substantial role in the pathophysiological mechanisms underlying several brain disorders. However, the mechanisms underlying the lipid profile in stress-induced maladaptations and how these changes can impact distinct neuronal circuits and behavioral states remain to be fully elucidated. Here, we investigated the effects of p11 deficiency in combination with stress by using p11KO mice and chronic stress mouse models of depression to study spatial lipidomic and transcriptomic signatures in the mouse nucleus accumbens. Our results show that p11 deficiency and stress induce depression-related maladaptive phenotypes and provide novel evidence that these responses are associated with phospholipid dyshomeostasis in the nucleus accumbens. Phospholipid disturbances were predominantly related to phosphatidylethanolamine (PE) and ether PE metabolism, along with targets involved in the PE biosynthetic pathway. Moreover, chelerythrine administration, a compound reported to disrupt phospholipid balance, induces PE changes and depression-like behaviors. Altogether, the present study provides evidence that alterations in phospholipid-related pathways may alter reward/anti-reward circuits and how these changes might be implicated in stress-related disorders.

Parkinson's disease (PD) is characterized by Lewy body pathology, mainly consisting of accumulation of aggregated α-synuclein and lipid contents. Lipid dyshomeostasis has frequently been observed in PD, and compelling evidences indicate that lipids play critical roles in modulating α-synuclein toxicity. However, how α-synuclein regulates brain lipid composition remains poorly understood. Here, we used dual polarity matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) to spatially profile brain lipids in a unilateral adeno-associated virus (AAV)-α-synuclein mouse model of Parkinsonism. We identified region-specific alterations in sphingolipids and glycerophospholipids in the substantia nigra and striatum of these mice. In sphingolipids, α-synuclein overexpression altered certain monosialotetrahexosylgangliosides (GM1s), sphingomyelins (SMs), and sulfated hexosyl ceramides (SHexCers; a.k.a. sulfatides). Glycerophospholipid changes followed a desaturation pattern: polyunsaturated fatty acid (PUFA)-containing species were decreased, while saturated and mono-unsaturated species were increased. Additionally, oxidized phosphatidylcholine (PC) lipids, such as SAzPC (1-stearoyl-2-azelaoyl-sn-PC) and PAzPC(1-palmitoyl-2-azelaoyl-sn-PC), were elevated in the substantia nigra, and ether phosphatidylethanolamines (PEs) were reduced in the substantia nigra but increased in the striatum. Our study provides a comprehensive, spatially resolved lipidomic landscape of α-synuclein–induced pathology in the nigrostriatal pathway, offering new insights into lipid dysregulation in experimental PD and a framework for future therapeutic exploration.

Free fatty acids (FFAs) are bioactive mediators of inflammation, energy metabolism, and membrane remodeling, yet their spatial organization within the Alzheimer's disease (AD) brain and at individual amyloid-β (Aβ) plaques has remained inaccessible. We developed a novel, chemically tailored MALDI workflow that enables simultaneous, spatially resolved detection of nearly 30 FFAs alongside over 100 complex lipid species within the same tissue section. Applying this approach to a transgenic AD mouse model across brain regions and disease stages, and combining it with single-plaque microenvironment analysis (SPMA) that treats each plaque as an individual analytical object, we uncover two previously inaccessible dimensions of plaque-associated lipid biology. FFA distributions form highly structured spatial compartments reflecting regional cytoarchitecture, with distinct enrichment of saturated, monounsaturated, and polyunsaturated species across cortical layers. Within Aβ plaques, nearly 75% of detected FFAs are significantly remodeled, with reciprocal enrichment of short saturated and highly unsaturated species alongside depletion of long-chain monounsaturated FFAs. This pattern is consistent with concurrent disruption of ELOVL-mediated elongation and FADS-mediated desaturation, including opposing enrichment of pro-inflammatory arachidonic acid and pro-resolving docosahexaenoic acid. Machine learning of single-plaque profiles reveals that FFA composition alone classifies plaque age with high accuracy, demonstrating that lipid remodeling continues after Aβ peptide composition has stabilized. Together, these findings establish spatial FFA profiling as a new analytical dimension in neurodegeneration research, revealing that Aβ plaques are dynamic lipid-metabolic microenvironments that continue to remodel long after Aβ deposition has stabilized.

While obesity and type 2 diabetes (T2D) are associated with altered dopaminergic activity in the central nervous system and in adipose tissue (AT), the directions and underlying mechanisms remain inconclusive. Therefore, we characterized changes in the abundance of dopamine, its metabolites, and receptors DRD1 and DRD2 in the brain and AT upon dietary intervention or obesity. Male Wistar rats were fed either a standard pellet diet, a cafeteria diet inducing obesity and insulin resistance, or a calorie-restricted diet for 12 weeks. Abundance of dopamine and its receptors DRD1 and DRD2 were examined in brain regions relevant for feeding behavior and energy homeostasis. Furthermore, DRD1 and DRD2 protein levels were analyzed in rat inguinal and epidydimal AT and in human subcutaneous and omental AT from individuals with or without obesity. Rats with diet-induced obesity displayed higher dopamine levels, as well as DRD1 or DRD2 receptor levels in the caudate putamen and the nucleus accumbens core. Surprisingly, caloric restriction induced similar changes in DRD1 and DRD2, but not in dopamine levels, in the brain. Both diets reduced DRD1 abundance in inguinal and epidydimal AT, but upregulated DRD2 levels in inguinal AT. Furthermore, in human obesity, DRD1 protein levels were elevated only in omental AT, while DRD2 was upregulated in both omental and subcutaneous AT. These findings highlight dopaminergic responses to changes in energy balance, occurring both in the brain and AT. We propose that dopaminergic pathways are involved in tissue crosstalk during the development of obesity and T2D.

L-DOPA-induced dyskinesia (LID) is a significant and treatment-limiting complication in Parkinson's disease (PD) therapy, yet its mechanisms remain poorly understood. We used high-resolution mass spectrometry imaging to map brain-region-specific alterations of glycerophospholipids and sphingolipids in a female macaque model of PD with and without LID following chronic L-DOPA treatment. LID was associated with depletion of antioxidant plasmalogen phosphatidylcholines in the globus pallidus interna, claustrum, and precentral gyrus-regions critical for motor function-and elevations of polyunsaturated fatty acid-containing glycerophospholipids, indicative of increased membrane fluidity. This lipid profile differed from similarly treated non-dyskinetic animals, suggesting lipid composition mediates differential susceptibility to LID. Lipid alterations correlated strongly with dyskinesia severity, dopamine, and L-DOPA concentrations, supporting a mechanistic link between lipid metabolism, neurotransmitter dysregulation, and LID. This comprehensive spatial lipidomic analysis identifies region-specific lipid dysregulation as a novel aspect of LID pathology, highlighting lipid pathways as potential therapeutic targets for mitigating dyskinesia.

Chromogranin A (CgA), a neuroendocrine pro-hormone, is proteolytically cleaved into bioactive peptides, most notably catestatin (CST) and pancreastatin (PST), which exert opposing effects on metabolic and inflammatory processes. Using CgA- and CST knockout (KO) mice, we investigated the roles of these peptides in pancreatic endocrine function, morphology, neurotransmitter dynamics, and systemic glucose homeostasis. CST-KO mice displayed impaired insulin secretion in vivo (but not ex vivo), disrupted islet architecture, and elevated catecholamine levels. In contrast, CgA-KO mice, which lack both CST and PST, exhibited reduced beta-cell mass but improved insulin sensitivity due to absence of PST. Peptide supplementation experiments in CgA-KO mice revealed that CST suppressed gluconeogenesis and enhanced glucagon regulation, whereas PST promoted insulin resistance and glucose production. Spatial mass spectrometry further demonstrated altered neurotransmitter and polyamine profiles in KO islets, implicating disrupted nerve-immune-islet crosstalk as a contributor to the observed metabolic phenotypes. Collectively, these findings identify CgA-derived peptides as critical regulators of islet function and highlight CST as a promising therapeutic candidate for diabetes and metabolic-inflammatory disorders.

Multiomics analysis of single tissue sections using matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) provides comprehensive molecular insights. However, optimizing tissue sample preparation for MALDI-MSI to achieve high sensitivity and reproducibility for various biomolecules, such as lipids, N-glycans, and tryptic peptides, presents a significant challenge. This study introduces a robust and reproducible protocol for the comprehensive sequential analysis of the latter molecules using MALDI-MSI in fresh-frozen rodent brain tissue samples. The optimization process involved testing multiple organic solvents, which identified serial washing in ice-cold methanol, followed by chloroform as optimal for N-glycan analysis. Integrating this optimized protocol into MALDI-MSI workflows enabled comprehensive sequential analysis of lipids (in dual polarity mode), N-glycans, and tryptic peptides within the same tissue sections, enhancing both the efficiency and reliability. Validation across diverse rodent brain tissue samples confirmed the protocol's robustness and versatility. The optimized methodology was subsequently applied to a transgenic Alzheimer's disease (AD) mouse model (tgArcSwe) as a proof of concept. In the AD model, significant molecular alterations were observed in various sphingolipid and glycerophospholipid species, as well as in biantennary and GlcNAc-bisecting N-glycans, particularly in the cerebral cortex. These region-specific alterations are potentially associated with amyloid-beta (A beta) plaque accumulation, which may contribute to cognitive and memory impairments. The proposed standardized methodology represents a significant advancement in neurobiological research, providing valuable insights into disease mechanisms and laying the foundation for potential preclinical applications. It could aid the development of diagnostic biomarkers and targeted therapies for AD and other neurodegenerative diseases, such as Parkinson's disease.

Inhibitors targeting amyloids formed by the human Islet Amyloid Polypeptide (hIAPP) are promising therapeutic candidates for type 2 diabetes. Peptide formulations derived from the nonamyloidogenic rat IAPP (rIAPP) sequence are currently used as hIAPP mimetics to support insulin therapy. rIAPP itself acts as a peptide inhibitor; yet, the structural-level consequences of such inhibition, particularly its impact on amyloid polymorphism, have not been studied in detail. Here, we conduct coaggregation experiments with varying rIAPP-to-hIAPP concentration ratios and employ high-resolution cryo-electron microscopy (Cryo-EM) to elucidate the polymorphism of the resulting fibril structures. Our results demonstrate that the polymorphism of hIAPP amyloids is highly sensitive to the electrostatic environment, which can be modulated by buffer composition, the concentration of the inhibitor, and cosolvents such as hexafluoroisopropanol (HFIP). Under native conditions, rIAPP associates with hIAPP but does not cross-aggregate, resulting in fibrils primarily composed of hIAPP. Significant inhibition is observed at relatively high concentrations of rIAPP. However, trace amounts of HFIP disrupt this inhibition, leading to increased fibril concentrations due to the formation of cross-seeded products composed of both hIAPP and rIAPP, as evidenced by mass spectrometry and two-dimensional infrared (2D IR) spectroscopy. These findings highlight the critical role of experimental conditions, particularly the electrostatic environment, in modulating amyloid polymorphism, cross-seeding, and inhibition. By providing structural insights into these processes, this study advances our understanding of peptide aggregation and offers valuable guidance for the rational design of more effective therapeutic inhibitors targeting hIAPP-related amyloidosis.

Mass spectrometry imaging (MSI) is a powerful tool for spatial metabolomics and biomarker discovery, but molecular identification remains challenging, particularly for low-abundance analytes with poor signal-to-noise ratios. Herein, a novel approach that utilizes a deuterated analog of the reactive matrix FMP-10 to enhance molecular identification is introduced. This isotopically labeled matrix enables precise determination of derivatization patterns, allowing the number and sequence of reactive functional groups in small molecules to be deduced. By observing specific mass shifts, the method provides additional structural information beyond high-resolution MS and MS/MS, addressing key limitations in MSI-based biomarker discovery. This innovative labeling strategy improves identification confidence for neurotransmitters and metabolites, making it a powerful addition to the MSI toolbox for complex tissue analysis. The findings represent a significant advance for spatial metabolomics, with particular advantages for neurochemical mapping in the study of neurodegenerative diseases.