Malotilate, a hepatoprotectant, suppresses CYP2E1 expression in rats

The expression of CYP2E1 was examined in hepatic tissue from rats treated with malotilate (MT), a hepatoprotectant. Microsomal p-nitrophenol hydroxylase activity in MT-treated rats was decreased to 66% and 47% of control activity at day 2 and 3 post-treatment. SDS-PAGE and immunoblot analyses of hepatic microsomes prepared from MT-treated rats showed that CYP2E1 levels were decreased below the limit of detectability. In contrast, CYP2B1 levels were increased in MT-treated microsomes, as assessed by immunoblot analyses. MT, however, failed to modulate CYP1A expression. RNA hybridization analysis revealed that CYP2E1 mRNA levels failed to change significantly by day 2 or 3 post-treatment, whereas microsomal epoxide hydrolase mRNA levels were elevated approximately 3-fold at the same time points. These results demonstrate that MT effectively suppresses CYP2E1 expression in the absence of transcriptional inactivation.