Effect of tamoxifen, raloxifen and tibolon on bile components in ovariectomized rats

The aim of the study was to investigate the effect of ovariectomy on the bile composition in order to estimate the ability of selective estrogen receptor modulators (SERMS) (tibolon, tamoxifen, raloxifen) to modify the ovariectomy-induced disorders. The study was carried out on the ovariectomized female Wistar rats. Tibolon (1 mg kg(-1) 24 h(-1)), tamoxifen (5 mg kg(-1) 24 h(-1)) and raloxifen (10 mg kg(-1) 24 h(-1)) were administered for 42 days. Under anesthesia bile was collected during 6h period. The ovariectomy increased significantly the excretion of biliary acids and calcium in bile and decreased the excretion of cholesterol and chloride. In rats treated with tamoxifen and raloxifen the excretion and concentration of cholesterol in bile were significantly reduced in comparison with ovariectomized rats. In rats treated with tibolon these values were increased. Moreover in rats treated with tamoxifen and raloxifen the concentrations of calcium in bile were significantly reduced. Tibolon had no significant effect on bile calcium concentrations. The therapy with tamoxifen, raloxifen and tibolon decreased the serum cholesterol concentrations, whereas the bile acid concentrations were increased in comparison with ovariectomized control. The drugs studied had no significant effect on calcium and chloride serum concentrations. Our results suggest that the therapy with tamoxifen and raloxifen may have the positive effect on bile composition in ovariectomized rats and probably may prevent the gallstone formation.