Decreased melatonin secretion is associated with increased intestinal permeability and marker of endotoxemia in alcoholics

Chronic heavy alcohol use is known to cause gut leakiness and alcoholic liver disease (ALD), but only 30% of heavy drinkers develop increased intestinal permeability and ALD. The hypothesis of this study was that disruption of circadian rhythms is a potential risk factor in actively drinking alcoholics for gut leakiness and endotoxemia. We studied 20 subjects with alcohol use disorder (AD) and 17 healthy controls (HC, 6 day workers, 11 night workers). Subjects wore a wrist actiwatch for 7 days and underwent a 24-h dim light phase assessment and urine collection for intestinal permeability. The AD group had significantly less total sleep time and increased fragmentation of sleep (P < 0.05). AD also had significantly lower plasma melatonin levels compared with the HC [mean area under the curve (AUC) 322.78 +/- 228.21 vs. 568.75 +/- 304.26 pg/ml, P = 0.03]. In the AD group, AUC of melatonin was inversely correlated with small bowel and colonic intestinal permeability (lactulose-to-mannitol ratio, r = -0.39, P = 0.03; urinary sucralose, r = -0.47, P = 0.01). Cosinor analysis of lipopoly-saccharide-binding protein (marker of endotoxemia) and lipopolysaccharide every 4 h for 24 h in HC and AD subjects had a midline estimating statistic of rhythm of 5,026.15 +/- 409.56 vs. 6,818.02 +/- 628.78 ng/ml (P < 0.01) and 0.09 +/- 0.03 vs. 0.15 +/- 0.19 EU/ml (P < 0.05), respectively. We found plasma melatonin was significantly lower in the AD group, and lower melatonin levels correlated with increased intestinal permeability and a marker of endotoxemia. Our study suggests the suppression of melatonin in AD may promote gut leakiness and endotoxemia.