title: Sex differences in hepatic cytochrome P-450 monooxygenase activities in rainbow trout during an annual reproductive cycle.
abstract: Hepatic microsomal cytochrome P-450 monooxygenase activities were investigated in rainbow trout during an annual reproductive cycle. The fish were kept in tanks supplied with fresh water at a constant temperature of 10 degrees C. The daily light and darkness cycle was adjusted to follow the natural photoperiod. Sampling was performed once every month for 1 year. Higher benzo(a)pyrene-hydroxylase (or aryl hydrocarbon hydroxylase; AHH), ethoxycoumarin-O-deethylase (ECOD) and ethylmorphine-N-demethylase (END) activities and cytochrome P-450 content were found during the late stage of sexual development in rainbow trout. When monooxygenase activities were expressed on a per cytochrome P-450 basis, sex-dependent differences were observed only for AHH and ECOD activities. It was thus found that sex-dependent variations of END were closely correlated with the total amount of cytochrome P-450. The results indicate that differences exist in hepatic cytochrome P-450 isoenzyme patterns between the sexes in rainbow trout. The similarity of the annual pattern of plasma levels of oestradiol and testosterone to that of sex-dependent differences in the cytochrome P-450 monooxygenases support the contention that sex steroids play a role in regulating the cytochrome P-450 system.
authors.affiliation: Department of Zoophysiology, University of Göteborg, Sweden.
authors.forename: L
authors.initials: L
authors.lastname: Förlin
authors.forename: C
authors.initials: C
authors.lastname: Haux
mesh_terms: D015660:7-Alkoxycoumarin O-Dealkylase / Q000032:analysis; D000818:Animals; D001579:Benzopyrene Hydroxylase / Q000032:analysis; D001835:Body Weight; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004958:Estradiol / Q000097:blood; D005037:Ethylmorphine-N-Demethylase / Q000032:analysis; D005260:Female; D007527:Isoenzymes; D008099:Liver / Q000033:anatomy & histology / Q000201:enzymology*; D008297:Male; D009929:Organ Size; D012098:Reproduction / Q000502:physiology*; D012487:Salmonidae / Q000502:physiology*; D012727:Sex Characteristics; D013739:Testosterone / Q000097:blood; D014337:Trout / Q000378:metabolism / Q000502:physiology*
chemical_list: D007527:Isoenzymes; D013739:Testosterone; D004958:Estradiol; D003577:Cytochrome P-450 Enzyme System; D015660:7-Alkoxycoumarin O-Dealkylase; D001579:Benzopyrene Hydroxylase; D005037:Ethylmorphine-N-Demethylase