Effects of cortisol administration on components of the hepatic microsomal mixed function oxidase system (MFO) of immature rainbow trout (Salmo gairdnerii Rich.).

The effects of cortisol on components of the liver microsomal mixed function oxidase system (MFO) of immature and starved rainbow trout, Salmo gairdnerii, Rich., were studied 3, 7 and 21 days after intraperitoneal implantation of cortisol-containing cholesterol pellets. The treatment resulted in significantly elevated NADPH cytochrome c reductase activities, concomitant with elevated plasma cortisol levels, at all sampling events, while no significant effects on either liver cytochrome P-450 or microsomal protein contents was observed. The cortisol-treated fish lost considerably more body weight than corresponding controls during the experimental period, while the effects on liver wet weight and liver somatic index were inconclusive.