title: The effect of sex steroids and pregnenolone-16 alpha-carbonitrile on the hepatic microsomal monooxygenase system of rainbow trout (Salmo gairdneri).
abstract: Estradiol benzoate (EB-5 mg/kg) or testosterone propionate (TP-50 mg/kg) administration to sexually immature rainbow trout resulted in an increase in liver weight to body weight ratios, and a diminution in hepatic microsomal benzphetamine-N-demethylation (BeND), ethoxycoumarin- and ethoxyresorufin-O-deethylations (ECOD, EROD) and cytochrome(s) P-450 content when compared to corn oil-pretreated controls. A low dose of TP (2 mg/kg) caused an increase in cytochrome(s) P-450 content but had no effect on the selected monooxygenase activities. EB administration prior to treatment with 150 mg/kg beta-naphthoflavone caused a dose-dependent decrease in the magnitude of induction of cytochrome(s) P-450 and associated catalytic activities. These data suggest that the sex differences in monooxygenation observed in prespawning trout are mediated via the sex steroids and that fish may respond differently to inducers depending on their reproductive state at the time of exposure. Administration of the synthetic steroid, pregnenolone-16 alpha-carbonitrile (PCN), resulted in an increase in BeND and ECOD but had no effect on EROD or cytochrome(s) P-450 content.
mesh_terms: D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004958:Estradiol / Q000494:pharmacology*; D008099:Liver / Q000187:drug effects; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology*; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D009929:Organ Size / Q000187:drug effects; D011285:Pregnenolone Carbonitrile / Q000494:pharmacology*; D012741:Sexual Maturation; D013739:Testosterone / Q000494:pharmacology*; D014337:Trout
chemical_list: D011285:Pregnenolone Carbonitrile; D013739:Testosterone; D004958:Estradiol; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases