INDUCTION OF CYP ISOENZYMES IN VARIOUS ORGANS OF RATS BY 3-METHYLCHOLANTHRENE OR BETA-NAPHTHOFLAVONE

Induction of cytochrome P450 (CYP) isoenzymes in various organs of rat s treated with 3-methylcholanthrene (3-MC) and beta-naphthoflavone (BN F) was immunohistochemically and biochemically investigated. Fifteen m ale F344 rats were divided into three equal groups. Group 1 was untrea ted as a control. On days 3, 4, 13 and 14, group 2 animals received 3- MC (20 mg/kg body wt i.p.) dissolved in corn oil while group 3 animals were given BNF (50 mg/kg body wt i.p.) dissolved in corn oil, at days 1, 2, 3, 4, 11, 12, 13 and 14. On days 4 and 14, two or three animals in each group were sacrificed, 15 h after administration of the last test compound. Induction of CYP 1A1, 2C11, 2D1, 2E1, 3A2 and 4A1 in va rious organs was immunohistochemically examined and the levels of CYP 1A1 protein were measured by Western blotting. 3-MC and BNF induced CY P isoenzymes not only in the liver, but also in the small intestine, l arge intestine, prostate and seminal vesicles. The results indicate th at xenobiotic metabolism can occur in various organs.