title: Regulation of rat hepatic cytochrome P-450: age-dependent expression, hormonal imprinting, and xenobiotic inducibility of sex-specific isoenzymes.
abstract: The influence of age, sex, and hormonal status on the expression of eight rat hepatic cytochrome P-450 (P-450) isoenzymes was evaluated by both catalytic and immunochemical methods. The male specificity of P-450 2c(male)/UT-A, the major microsomal steroid 16 alpha-hydroxylase of uninduced rat liver [Waxman, D.J. (1984) J. Biol. Chem. 259, 15481-15490], was shown to reflect its greater than or equal to 30-fold induction at puberty in male but not in female rats. The female specificity of P-450 2d(female)/UT-I was shown to reflect its developmental induction in females. P-450 PB-2a/PCN-E was shown to mediate greater than or equal to 85% of microsomal steroid 6 beta-hydroxylase activity; the male specificity of this P-450 largely reflects its developmental suppression in female rats. Neonatal gonadectomy and hormonal replacement experiments established that neonatal androgen "imprints" or programs the male rat for developmental induction of P-450 2c(male)/UT-A, for maintenance of P-450 PB-2a/PCN-E, and for suppression of P-450 2d(female)/UT-I, all of which occur in male rats at puberty. By contrast, the expressed levels of P-450 isoenzymes PB-1/PB-C, 3/UT-F, PB-4/PB-B, ISF-G, and beta NF-B were mostly unaffected by the rats' age, sex, and hormonal status. Studies on the sex specificity of P-450 induction established that the response of these latter five isoenzymes to the P-450 inducers phenobarbital, beta-naphthoflavone, pregnenolone-16 alpha-carbonitrile, and isosafrole is qualitatively and quantitatively equivalent in females as in males.
mesh_terms: D000375:Aging; D000818:Animals; D000906:Antibodies; D000936:Antigen-Antibody Complex; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis*; D005260:Female; D007527:Isoenzymes / Q000096:biosynthesis*; D008099:Liver / Q000254:growth & development*; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012737:Sex Factors; D013250:Steroid Hydroxylases / Q000037:antagonists & inhibitors / Q000096:biosynthesis
chemical_list: D000906:Antibodies; D000936:Antigen-Antibody Complex; D065607:Cytochrome P-450 Enzyme Inhibitors; D007527:Isoenzymes; D003577:Cytochrome P-450 Enzyme System; D013250:Steroid Hydroxylases