Effects of bile acid feeding on hepatic deoxycholate 7 alpha-hydroxylase activity in the hamster.

In order to investigate the effects of bile acid feeding on hepatic microsomal deoxycholate 7 alpha-hydroxylase activity, three different bile acids were administered (0.2% w/w in chow) to hamsters for two weeks. Deoxycholate 7 alpha-hydroxylase activity was increased markedly by feeding of cholic acid (CA) and slightly by deoxycholic acid (DCA). Chenodeoxycholic acid (CDCA) had little effect on the enzyme activity. Feeding each of the bile acids significantly inhibited the activity of cholesterol 7 alpha-hydroxylase in the order CDCA greater than or equal to DCA greater than CA. There was no correlation between deoxycholate 7 alpha-hydroxylase activity and cholesterol 7 alpha-hydroxylase activity. It is concluded that the activity of deoxycholate 7 alpha-hydroxylase is up-regulated by feeding DCA and CA and that the mechanism seems to be different from that of cholesterol 7 alpha-hydroxylase. The increased activity of hepatic deoxycholate 7 alpha-hydroxylase by CA and DCA should be beneficial in minimizing the toxic effects of DCA in the hamster.