title: Induction of cytochrome P-450 in congenic C57BL/6J mice by isosafrole: lack of correlation with the Ah locus.
abstract: Isosafrole induction of cytochrome P-450 was compared in congenic strains of C57BL/6J mice, one of which expresses normal levels of the Ah receptor [B6(Ahb)], and another that does not contain a measurable receptor concentration [B6(Ahd)]. Using sucrose gradient analysis of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) binding, an Ah receptor concentration of 69.1 +/- 3.8 fmol/mg protein was measured in the hepatic cytosol from B6(Ahb) mice, while no receptor could be detected in the cytosol from B6(Ahd) mice. Isosafrole treatment (75 mg/kg X 3 days) increased the total hepatic microsomal cytochrome P-450 content to the same extent in the two congenic strains. The level of microsomal monooxygenase induction in the isosafrole-treated B6(Ahd) mice was greater than that of B6(Ahb) mice for ethylmorphine N-demethylase and isosafrole metabolite-complex formation, the latter a measure of cytochrome P2-450. In the case of 7-ethoxycoumarin O-deethylase only the isosafrole-treated B6(Ahd) mice had elevated microsomal activity. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) also revealed a similar induction pattern for the two congenic strains, following isosafrole treatment. Thus, the isosafrole treated B6(Ahd) mice produced an equivalent or slightly larger induction of cytochrome P-450 than the B6(Ahb) mice, suggesting that there is no direct role for the Ah receptor in the regulation of these cytochrome P-450 monooxygenase activities by isosafrole.
mesh_terms: D015660:7-Alkoxycoumarin O-Dealkylase; D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004149:Dioxoles / Q000494:pharmacology*; D004790:Enzyme Induction / Q000187:drug effects; D005037:Ethylmorphine-N-Demethylase / Q000378:metabolism; D008040:Genetic Linkage; D051379:Mice; D008810:Mice, Inbred C57BL / Q000235:genetics / Q000378:metabolism; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology; D010105:Oxygenases / Q000378:metabolism; D000072317:Polychlorinated Dibenzodioxins / Q000378:metabolism; D018336:Receptors, Aryl Hydrocarbon; D011955:Receptors, Drug / Q000235:genetics / Q000502:physiology*; D012451:Safrole / Q000494:pharmacology*
chemical_list: D004149:Dioxoles; D000072317:Polychlorinated Dibenzodioxins; D018336:Receptors, Aryl Hydrocarbon; D011955:Receptors, Drug; D003577:Cytochrome P-450 Enzyme System; D010105:Oxygenases; D015660:7-Alkoxycoumarin O-Dealkylase; D005037:Ethylmorphine-N-Demethylase; D012451:Safrole; C015959:isosafrole