Repeated Binge-Like Alcohol Intoxication: Depot-Specific Adipose Tissue Immuno-Metabolic Dysregulation
Repeated binge-like alcohol intoxication (RBAI) induces whole-body insulin resistance, which is predicted to increase the risk for metabolic syndrome and type 2 diabetes. Previously, we showed that acute alcohol intoxication increases mesenteric lymphatic permeability, perilymphatic adipose tissue (PLAT) inflammation, and circulating lipopolysaccharide levels in rats. We hypothesize that mesenteric lymphatic hyperpermeability, adipose tissue inflammation and associated dysregulated adipokine expression, and insulin signaling are central mechanisms underlying whole-body metabolic dysregulation resulting from RBAI. To test this hypothesis, male Sprague–Dawley rats surgically fitted with an intragastric catheter received a bolus of 2.5 g/kg/day of alcohol (12.5% alcohol w/v) or isocaloric dextrose in Vanilla Ensure (116 kcal/kg/day) for 3 days. Mesenteric lymphatic permeability, mesenteric (MFAT = PLAT) and subcutaneous (SFAT) adipose tissue inflammatory milieu, circulating adipokines, and markers of insulin responsiveness (pAKT and PTP1B protein expression) were determined following the last alcohol/dextrose administration. RBAI resulted in increased lymphatic permeability, MFAT-specific expression of inflammatory cytokines and markers of inflammatory cells (macrophages, dendritic, and T cells), decreased circulating adiponectin and visfatin levels, and MFAT-specific attenuation of insulin-stimulated protein kinase B phosphorylation (Ser473) compared with dextrose-treated control animals. These results suggest that RBAI-induced mesenteric lymphatic hyperpermeability promotes inflammatory milieu, decreased insulin-sensitizing adipokines, and impaired insulin signaling in MFAT, which we propose may be an early event preceding systemic metabolic dysregulation. We speculate that RBAI-induced increase in gut-derived toxins, promoting lymphatic leak, and MFAT inflammatory milieu are mechanisms deserving further investigation to elucidate lymphatic-MFAT crosstalk events that precede and predispose for alcohol-induced insulin resistance.