Effects of vanadate on hepatic cytochrome P-450 expression in streptozotocin-diabetic rats.

The ability of sodium metavanadate to reverse the effects of streptozotocin-induced diabetes on hepatic cytochrome P-450 isozymes was examined in male rats. Streptozotocin caused P-450h levels to fall 95%, and P-450j and P-450b levels to rise 8- and 40-fold, respectively, after 1 week. When diabetic rats were administered metavanadate in the drinking water for 7 days, P-450h apoprotein and mRNA levels remained no different from those of untreated diabetic rats, whereas levels of P-450b and P-450j decreased toward those of control rats. Metavanadate also lowered serum triglyceride and 3-hydroxybutyrate levels without lowering serum glucose in the diabetic rats. Furthermore, P-450h mRNA levels correlated well with levels of P-450h apoprotein for all treatment groups, indicating that P-450h suppression in diabetic rats is under pretranslational control and is independent of the increased expressions of P-450j and P-450b, and of the hyperlipidemia and ketosis that occurs in diabetes. Vanadate is capable of separating the effects of diabetes on expression of individual P-450 isozymes.