Effects of low ethanol consumption on nonalcoholic steatohepatitis in mice

Several recent clinical and epidemiological studies have suggested inhibitory effects of light-to-moderate alcohol consumption on nonalcoholic fatty liver disease (NAFLD)/nonalcoholic steatohepatitis (NASH); however, these effects have not been confirmed in experimental studies. Therefore, in this study, we examined the effects of small amounts of ethanol consumption on a mouse model of NASH. Nine-week-old male obese mice (db/db mice) were divided into the following groups: control, high-fat, and low-ethanol groups. The control group was provided ad libitum access to a control liquid diet, the high-fat group was provided access to a high-fat liquid diet, and the low-ethanol group was provided access to the high-fat liquid diet supplemented with 0.1% (w/w) ethanol. Eight weeks later, the mice were sacrificed and serum biochemical, histopathological, and molecular analyses were performed. Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were significantly lower in the low-ethanol group than in the high-fat group (p = 0.033 and 0.037, respectively). Liver histopathological analysis showed that intralobular and portal inflammation was significantly milder in the low-ethanol group than in the high-fat group (p = 0.018 and 0.041, respectively). However, no significant differences were observed among the groups in serum insulin and adiponectin levels, hepatic 4-hydroxynonenal (oxidative injury marker) levels, and hepatic cytokine and receptor gene expression levels. In conclusion, the serum transaminase levels and hepatic inflammation in NASH model mice improved after administration of small amounts of ethanol. This study directly demonstrated inhibitory effects of small amounts of ethanol on NASH in mice. The mechanisms underlying these inhibitory effects remain to be elucidated.