Diurnal variations in intestinal barrier integrity and liver pathology in mice: implications for alcohol binge.

Recent studies suggest that circadian rhythms regulate intestinal barrier integrity, but it is not clear whether there are daily variations in barrier integrity. This study investigated daily variations in intestinal barrier integrity, including whether there are differences in alcohol-induced intestinal barrier dysfunction after an alcohol binge at different times of day and whether this is associated with concurrent liver injury. C57BL6/J male mice were fed a standard chow diet, an alcohol-containing liquid diet, or an alcohol control diet for 4 wk. During week 5 (i.e., on days 43-45), mice received three once-daily gavages of alcohol (6 g/kg) or the control (phosphate-buffered saline) at the same time each day. Immediately after the binge on the second day, intestinal permeability was assessed. Four hours after the third and final binge, mice were euthanized and tissue samples collected. The results demonstrated diet-specific and outcome-specific effects of time, alcohol, and/or time by alcohol interaction. Specifically, the alcohol binge robustly influenced markers of intestinal barrier integrity, and liver markers were robustly influenced by time of day. Only intestinal permeability (i.e., sucralose) demonstrated a significant effect of time and also showed a binge by time interaction, suggesting that the time of the alcohol binge influences colonic permeability. NEW & NOTEWORTHY This study investigated daily variations in intestinal barrier integrity, including whether there are differences in alcohol-induced intestinal barrier dysfunction after an alcohol binge at different times of day and whether this is associated with concurrent liver injury. We conclude that 1) alcohol binge significantly impacted markers of intestinal permeability, 2) time of day significantly affected liver outcomes, and 3) the time of day influenced colonic permeability.