NADPH-CYTOCHROME P-450 REDUCTASE, CYTOCHROME-P-450 2C11 AND P-450 1A1, AND THE ARYL-HYDROCARBON RECEPTOR IN LIVERS OF RATS FED METHYL-FOLATE-DEFICIENT DIETS

We investigated three hepatic cytochrome P-450 isozymes and the aryl h ydrocarbon (Ah) receptor in rats fed one of the following three diets for 15 months: a diet containing the AIN vitamin mixture (control), th e control diet devoid of choline and folate (CFD), or the CFD diet dev oid of niacin (CFND). Hepatic tumors developed in all CFD-and CFND-fed rats. Western blot analyses of nontumor hepatic tissue showed that NA DPH-cytochrome P-450 reductase (P-450 reductase) increased significant ly in the CFD and CFND groups compared with the control group. Hepatic cytochrome P-450 2C11 (CYP2C11) was not detectable in the CFD and CFN D groups compared with the control group. Ah receptor and cytochrome P -450 1A1 (CYP1A1) were detected in higher amounts in livers of both de ficient groups. CYP1A1 is an enzyme associated with bioactivation of e xogenous genotoxins. To our knowledge, this is the first time it has b een shown that CYP1A1 and the Ah receptor are induced by dietary defic iencies.