Effects of bile salt supplementation on biliary secretion in estrogen-treated rats.

The aim of the present study was to determine whether bile acid feeding to rats can reverse ethinyl estradiol-induced cholestasis. Animals received ethinyl estradiol (2 mg/kg/day) for 6 days or were coinfused with estrogen plus various bile acids (60 mg/kg/day). Cholestasis could be significantly prevented by tauroursodeoxycholic acid, was partly corrected by ursodeoxycholic acid, and was unchanged by chenodeoxycholic acid. Total bile salt secretion was increased in every group. The secretion of the major primary bile acids (cholic acid and beta-muricholic acid) was restored to a large extent in rats supplemented with tauroursodeoxycholate but not in chenodeoxycholate-fed rats. In the former group, the canalicular transport of taurocholate and the bile salt pool size were identical with those of control rats. The hydrophilic-hydrophobic balance of the administered bile salt species appears to be an essential factor in the restoration of bile secretion, the more hydrophilic bile salt having the more hepatoprotective effect.