Incretin-Related Pathology and Serum Exosome Detection in Experimental Alcohol-Related Brain Damage

Abstract

Alcohol’s chronic neurotoxic and degenerative effects mediate alcohol-related brain damage (ARBD), which is marked by neurobehavioral, cognitive, and motor deficits. Major underlying abnormalities include impairments in signaling through the insulin and insulin-like growth factor (IGF) pathways, which regulate energy metabolism. This study examined the potential role of dysregulated incretin network-related mechanisms as mediators of ARBD and evaluated a non-invasive serum exosome (S-EV)-based approach for detecting brain abnormalities. Frontal lobe tissue and S-EVs isolated from Long–Evans adolescent rats maintained for 2 weeks on control or 24% ethanol (caloric) containing liquid diets (n = 8/group) were analyzed using multiplex magnetic bead-based enzyme-linked immunosorbent assays (ELISAs). ARBD was associated with significantly reduced insulin, C-peptide, glucagon, ghrelin, leptin, GIP, and amylin levels in the frontal lobe and/or S-EV samples. In contrast, chronic ethanol exposure had no significant effects on PP, PYY, or GLP-1, and it did not increase proinflammatory cytokine expression. Chronic ethanol feeding broadly affected (primarily inhibiting) the expression of metabolic hormones linked to insulin/IGF signaling. The reductions in GIP and amylin suggest potential targets for therapeutic intervention to enhance brain energy metabolism via insulin networks. On the other hand, the findings suggest that GLP-1 receptor agonists may have limited efficacy in remediating the effects of ARBD. Finally, the results support the use of non-invasive S-EV assays to detect and guide treatment for metabolic brain dysfunction in ARBD.