Effect of bile acid feeding on hepatic steroid 12 alpha-hydroxylase activity in hamsters.

The effects of feeding cholic acid, chenodeoxycholic acid and ursodeoxycholic acid on the activity of the hepatic steroid 12 alpha-hydroxylase, gallbladder bile acid composition, fecal neutral sterol output, cholesterol synthesis and bile acid synthesis were determined in female hamsters. The 12 alpha-hydroxylase activity was inhibited to 56% by cholic acid, to 62% by chenodeoxycholic acid, and to 78% by ursodeoxycholic acid compared with the control. Bile acid composition was altered by feeding of cholic acid and chenodeoxycholic acid to be rich in the given bile acids. Fecal neutral sterol output increased about twice by feeding chenodeoxycholic acid and ursodeoxycholic acid, whereas cholic acid had no significant effect. Body cholesterol synthesis increased to 217% by chenodeoxycholic acid and to 274% by ursodeoxycholic acid, whereas effect of cholic acid was not significant. Bile acid synthesis was suppressed to 48% of control only by chenodeoxycholic acid. A positive correlation between the 12 alpha-hydroxylase activity and the bile acid synthesis was observed in the control, chenodeoxycholate-fed and ursodeoxycholate-fed animals. In conclusion, ursodeoxycholic acid might have less inhibitory effect on the steroid 12 alpha-hydroxylase and the bile acid synthesis than chenodeoxycholic acid.