Glutathione and bile acid synthesis. II. Effect of hepatic glutathione content on the activity and mRNA levels of cholesterol 7 alpha-hydroxylase in the rat.

Hepatic cholesterol 7 alpha-hydroxylase (CH-7 alpha) activity in intact rats depleted of glutathione (GSH) was reduced significantly (P < 0.007) compared with that in untreated controls. Northern blot analysis of poly A+ mRNA isolated from GSH-depleted and control rat livers showed that there was a reduction in mRNA for CH-7 alpha in treated rats that was commensurate with the reduction in CH-7 alpha activity. The fact that the level of transferrin mRNA was unaltered by the depletion of GSH suggests that the change in steady-state CH-7 alpha mRNA content is specifically sensitive to GSH content. This observation extends previous in vitro findings and provides strong justification for a more detailed biochemical investigation into the interaction between GSH levels and the regulation of CH-7 alpha mRNA levels.