3-Methylcholanthrene and pyridine effects on CYP1A1 and CYP1A2 expression in rat renal tissue

The effects of 3-methylcholanthrene (3-MC) and pyridine on rat renal cytochrome P450 (CYP) 1A1 and 1A2 mRNA expression have been examined by Northern-blot analysis and reverse transcriptase-polymerase chain reaction (RT-PCR), followed by Southern-blot analysis of the PCR products. Northern-blot hybridization and RT-PCR analyses of kidney poly(A)+ RNA revealed that 3-MC treatment produced a time-dependent increase in the renal CYP1A1 and 1A2 mRNA levels, with CYP1A1 and 1A2 mRNA levels maximally increased at 24 and 18 hr, respectively, after treatment. These data were confirmed via RT-PCR analysis using a subsaturating level of cDNA template and by Southern-blot analysis of the PCR products. This approach served as the foundation for examining the effects of pyridine on CYP1A1 and 1A2 expression in renal tissue. RT-PCR analysis of renal CYP1A1 and 1A2 poly(A)+ RNA levels after treatment with pyridine (200 mg/kg/day for 3 consecutive days) revealed that CYP1A1 mRNA levels were maximally elevated approximately 10-fold after pyridine treatment for 2 consecutive days, whereas CYP1A2 mRNA levels were maximally elevated approximately 3-fold at 24 hr after treatment. The mRNA levels of glyceraldehyde 3-phosphate dehydrogenase, which served as an internal control, remained constant after 3-MC or pyridine treatment. These results show that expression of CYP1A1 and 1A2 mRNAs is enhanced in renal tissue after exposure to 3-MC or pyridine, and that constitutive expression of CYP1A1 seems to be greater than that of CYP1A2 in renal tissue.