Effects of oestradiol-17 beta and hypophysectomy on hepatic mixed function oxidases in rainbow trout.
The effects of oestradiol-17 beta and/or hypophysectomy on the metabolism of benzo (a) pyrene (BP), paranitroanisole (PNA), ethylmorphine (EM) and 7-ethoxycoumarin by liver microsomes from juvenile rainbow trout, Salmo gairdnerii, were studied. Administration of oestradiol-17 beta caused significant decrease in the liver microsomal metabolism of BP, PNA and EM while hypophysectomy had no effect. The suppressive effect of oestradiol-17 beta on the mixed function oxidases was as pronounced in hypophysectomized as in sham-operated fish, indicating that this effect of oestradiol-17 beta is mainly direct and independent of the pituitary gland. Administration of oestradiol-17 beta caused a significant increase in the apparent Km values of the PNA-O-demethylase whereas no alteration was seen in the apparent Vmax values of the enzyme. The results indicate that oestradiol-17 beta may play a role in the regulation of hepatic mixed function oxidases in rainbow trout.
D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004958:Estradiol / Q000494:pharmacology*; D007016:Hypophysectomy; D008099:Liver / Q000201:enzymology*; D008862:Microsomes, Liver / Q000201:enzymology; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D010088:Oxidoreductases / Q000378:metabolism*; D010902:Pituitary Gland / Q000502:physiology; D012487:Salmonidae / Q000378:metabolism*; D014337:Trout / Q000378:metabolism*
D004958:Estradiol; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D010088:Oxidoreductases