Abstract: Objective To investigate the effect of hydronidone on CCl4- induced liver fibrosis in rats and explore the possible mechanism. Methods Sixty-six male SD rats were randomized into 5 groups, including a control group (n=10), a liver fibrosis model group (n=20), 2 hydronidone dose groups (100 and 250 mg/kg; n=12), and a pirfenidone (250 mg/kg) treatment group (n=12). Rat models of liver fibrosis were established by subcutaneous injection of CCl4 in all but the control group. Hydronidone and pirfenidone were given daily at the indicated doses by intragastric administration for 6 weeks. After the treatments, serum samples were collected from the rats for detecting liver function parameters, and hydroxyproline content in the liver tissue was determined. Inflammation and fibrosis in the liver tissue were observed using HE staining and Sirius Red staining. In the cell experiment, human hepatic stellate cell line LX-2 was stimulated with TGF-β1 and treated with hydronidone or pirfenidone, and the expression levels of α-SMA, collagen type I and phosphorylated Smad3, phosphorylated p38, phosphorylated ERK1/2 and phosphorylated Akt were detected with Western blotting. Results In the rat models of liver fibrosis, treatment with hydronidone obviously improved the liver functions, reduced the content of hydroxyproline in the liver tissue, and significantly alleviated liver fibrosis (P<0.05). In LX-2 cells, hydronidone dose-dependently decreased the expression levels of α-SMA and collagen type I. In TGF-β1-stimulated cells, the phosphorylation levels of Smad3, P38, ERK, and Akt increased progressively with the extension of the treatment time, but this effect was significantly attenuated by treatment with hydronidone (P<0.05). Conclusion Hydronidone can inhibit the phosphorylation of the proteins in the TGF-β signaling pathway, thereby preventing TGF-β1-mediated activation of hepatic stellate cells, which may be a possible mechanism by which hydronidone alleviates CCl4-induced liver fibrosis in rats.

Key words: hydronidone; transforming growth factor β1; hepatic stellate cells; liver fibrosis