Effects of bile acids on fecal excretion of end products of cholesterol metabolism

Abstract

The influence of bile acids on liver cholesterol mobilization and on the excretion of fecal end products of cholesterol-4-C14 metabolism was studied in mice. Tissue cholesterol was elevated by feeding a fat-free diet containing cholesterol or cholesterol-4-C14. The mice were then divided into three groups: cholic acid treated, control and hyodeoxycholic acid treated. Fecal collections were made at intervals for 20 days, and steroids extracted and fractionated. The quantity of the sterol fractions and the C14 activity of the sterol and bile acid fractions were determined. Regression of hepatic cholesterol was followed at the same time intervals. Cholic acid inhibited liver cholesterol mobilization, while hyodeoxycholic acid effected a rapid regression of liver cholesterol to subnormal levels. Cholic acid depressed total steroid excretion, the depression occurring in the bile acid fraction; while excretion of fecal sterols remained relatively unaltered. Hyodeoxycholic acid greatly increased total steroid excretion. The increase was in the sterol fraction (95%), while bile acid excretion was depressed. These data indicate that bile acids are important factors in determining the rate and route of cholesterol metabolism.