Effect of Estradiol-17β on the Metabolism of Bile Acids in the Rat

The effect of estradiol-17β on the metabolism of bile acids has been studied in male rats. A 3-day acute treatment with 100 μg/100 g body weight of the hormone caused a decrease in serum cholesterol and an increase in hepatic cholesterol. A chronic treatment with the same quantity twice a week for 3 weeks induced hypercholesteremia, which continued for 10 days after the final dosage, but there was no change in hepatic total cholesterol. Fistula bile of both groups of treated rats collected during 30 min was analyzed for bile acid components. Hyodeoxycholic acid and/or chenodeoxycholic acid increased relative to cholic acid in both groups, as compared with the controls. Kinetic study of the metabolism of bile acids in the chronically treated rats revealed a more than twofold enlargement of the pool size but an almost unchanged half-life of chenodeoxycholic acid. As for cholic acid, essentially no change in pool size or half-life was observed. These results indicate that chronic treatment of male rats with estradiol-17β causes an increase in elimination of hepatic cholesterol via the bile acid pathway.