AIM:To evaluate the effect of chronic alcohol intake on the histopathological changes of the liver and to determine the contribution of epithelial-mesenchymal transition (EMT) to hepatic fibrogenesis. METHODS:Thirty male C57BL/6 mice were randomly divided into 3 groups as following: the mice in control group was given (ig) water; the mice in low-dose alcohol group (2.0 g·kg -1·d -1) and high-dose alcohol group (4.0 g·kg -1·d -1) were given (ig) alcohol for 5 months. Alcohol-induced histopathological changes of the liver or development of hepatic fibrosis were evaluated using the histological methods with HE and Masson trichrome staining. The apoptosis of the liver was detected by TUNEL fluorometric staining (counterstained with DAPI). The activity of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) was measured by an automated biochemical analyzer. The expression of fibroblast-specific protein 1 (FSP-1), α-smooth muscle actin (α-SMA) and E-cadherin in the hepatic tissues was detected by immunofluorescence examination. The protein levels of E-cadherin, α-SMA, FSP-1, transforming growth factor β 1 (TGF-β 1) and hypoxia-inducible factor 1α (HIF-1α) were analyzed by Western blotting. RESULTS:Compared with control, the activity of serum ALT and AST, and apoptotic index of liver tissues were increased in the mice treated with alcohol for 5 months. The histopathological changes of the livers in the mice of low-dose alcohol group included steatosis and mild liver fibrosis, while severe liver fibrosis was observed in the high-dose alcohol-treated mice. Chronic alcohol consumption induced the increase in malondialdehyde (MDA) level, and the decreases in the activity of superoxide dismutase (SOD) and catalase (CAT) in the livers. It also reduced E-cadherin expression and increased α-SMA expression. FSP-1 immunostaining and albumn immunostaining positive cells were co-localized in the hepatocytes of low-dose alcohol group, but only FSP-1 positive hepatocytes were observed in high-dose alcohol group. Chronic alcohol consumption decreased E-cadherin expression and increased α-SMA, FSP-1, TGF-β 1 and HIF-1α expression in a dose-dependent manner, but the HIF-1α expression was not altered between the 2 alcohol-treated groups. CONCLUSION:Chronic alcohol intake induces the progression of hepatic fibrosis. Some fibroblasts derive from hepatocytes in liver fibrosis via EMT. The underlying mechanism is associated with the changes of the redox state, and increased TGF-β 1 generation and HIF-1α expression.