AIM: To investigate the effects of troglitazone (TGZ), an anti-diabetic drug which activates peroxisome proliferator-activated receptor-γ(PPAR-γ), for liver tissue repair, and the development of ductular reaction, following common bile duct ligation (BDL) in rats. METHODS: Rats were supplemented with TGZ (0.2% w/w in the pelleted food) for 1 wk before BDL or sham operation. Animals were killed at 1, 2, or 4 wk after surgery. RESULTS: The development of liver fibrosis was reduced in rats receiving TGZ, as indicated by significant decreases of procollagen type Ⅰ gene expression and liver hydroxy-proline levels. Accumulation of α-smooth-muscle actin (SMA)-expressing cells surrounding newly formed bile ducts following BDL, as well as total hepatic levels of SMA were partially inhibited by TGZ treatment, indicating the presence of a reduced number and/or activation of hepatic stellate cells (HSC) and myofibroblasts. Development of the ductular reaction was inhibited by TGZ, as indicated by histochemical evaluation and hepatic activity of γ-glutamyl-transferase (GGT). CONCLUSION: Treatment with thiazolidinedione reduces ductular proliferation and fibrosis in a model of chronic cholestasis, and suggests that limiting cholangiocyte proliferation may contribute to the lower development of scarring in this system. AIM: To investigate the effects of troglitazone (TGZ), an anti-diabetic drug which activates peroxisome proliferator-activated receptor-γ (PPAR-γ), for liver tissue repair, and the development of ductular reaction, following common bile duct ligation METHODS: Rats were supplemented with TGZ (0.2% w / w in the pelleted food) for 1 wk before BDL or sham operation. Animals were killed at 1, 2, or 4 wk after surgery. RESULTS: The development of liver fibrosis was reduced in rats receiving TGZ, as indicated by significant reduction of procollagen type I gene expression and liver hydroxy-proline levels. Accumulation of α-smooth-muscle actin (SMA) -expressing cells surrounding newly formed bile ducts following BDL, as the as hepatic levels of SMA were partially inhibited by TGZ treatment, indicating the presence of a reduced number and / or activation of hepatic stellate cells (HSC) and myofibroblasts. Development of the ductular reaction was inhibited by TGZ, as indicate d by histochemical evaluation and hepatic activity of γ-glutamyl-transferase (GGT). CONCLUSION: Treatment with thiazolidinedione reduces ductular proliferation and fibrosis in a model of chronic cholestasis, and suggests that limiting cholangiocyte proliferation may contribute to the lower development of scarring in this system.