Effects of sho-saiko-to extract on fibrosis and regeneration of the liver in rats.

Sho-saiko-to, one of the most widely used Chinese herbal preparations, has long been used for the treatment of chronic liver diseases. We have investigated its effect in retarding the process of liver fibrosis and accelerating liver regeneration, especially its effect on Ito cells that are thought to be deeply involved with liver fibrosis. Sho-saiko-to extract and its active constituents were orally administered to rats with dimethylnitrosamine-induced liver-injury. After treatment with sho-saiko-to extract hepatic function improved, histopathological results confirmed repair of liver tissue, and retinoid levels increased. On the other hand, when active constituents of sho-saiko-to extract were administered alone, liver retinoid levels remained low, implying that interaction among active constituents of the extract was suppressing Ito cell activation. When sho-saiko-to extract was administered to 70% hepatectomized normal and liver-injured rats, liver weight, the number of S-phase-cells and retinoid levels increased with time. However, these changes were different for normal and liver-injured rats, suggesting that the site of action of sho-saiko-to extract in regenerating liver is different for normal and liver-injured rats. These results show that sho-saiko-to extract was useful for suppressing the activation of Ito cells.