Effects of soy protein on alcoholic liver disease in rats undergoing ethanol withdrawal

Objective: This investigation attempted to clarify the effects of soy protein on alcoholic liver disease (ALD) in rats undergoing ethanol withdrawal. Methods: Alcoholic liver disease was induced in rats by administration of a low-carbohydrate ethanol liquid diet for 12 weeks, after which the ethanol was withdrawn and the rats were divided into two experimental groups: a control group (EC group) and a soy protein group (EP group) for 4 weeks. Results: After the 12-week ALD-inducing period, the ethanol group had significantly higher hepatic lipid accumulation, oxidative stress and inflammation. We found that the EP group had significantly lower hepatic lipids, malondialdehyde, tumor necrosis factor-α, interleukin (IL)-1β, IL-6, hydroxyproline levels and myeloperoxidase activity compared to the EC group. Moreover, the fecal total cholesterol and total lipids were higher in the EP group. Expression of the hepatic cytochrome P450 2E1 (CYP2E1) protein in the EP group was significantly lower than that in the EC group, and the hepatic peroxisome proliferator-activated receptor (PPAR) α and cytochrome P450 4A (CYP4A) protein expressions in the EP group were significantly higher than those in the EC group. In the histopathological analysis, we also found that soy protein ameliorated fat accumulation in the liver. Conclusion: These results suggest that soy protein may improve alcohol-induced lipid accumulation, oxidative stress and inflammation by decreasing proinflammatory cytokines and CYP2E1 protein expression and by increasing PPARα and CYP4A protein expressions and fecal lipid excretion, thereby producing beneficial effects on ALD during ethanol withdrawal.