Induction of hepatic microsomal enzymes in rainbow trout by dietary aroclor 1254 and the effect of cyclopropene fatty acids

Graduation date: 1980A dietary level of Aroclor 1254 (100 ppm) was fed\ud to rainbow trout (Salmo gairdneri) for 15 weeks to\ud determine the effects on hepatic microsomal enzyme induction.\ud Fish were also fed combined polychlorinated\ud biphenyl (PCB) (100 ppm) and cyclopropene fatty acids\ud (CPFA) (50 ppm) to determine the effects on mixed\ud function oxidase (MFO) induction.\ud Dietary PCBs markedly induced the microsomal activities\ud of 7-ethoxyresorufin O-deethylase, 7-ethoxy-coumarin\ud O-deethylase, and benzo(a)-pyrene monooxygenase.\ud Ethoxyresorufin O-deethylase activity continued\ud to increase to a level 77-fold higher than control at\ud week 15. Ethoxycoumarin O-deethylase and benzo(a)-pyrene monooxygenase activities increased to 7.1-fold\ud and 48-fold over control at week 9 and then slightly\ud decreased to 6.8-fold and 45-fold over control at week\ud 15, respectively. Cytochrome P450 values remained\ud approximately 2-fold above controls from week 5 through\ud week 15. At weeks 1 and 3, cytochrome P450 levels were\ud not significantly different from control.\ud Ethoxyresorufin O-deethylase, ethoxycoumarin\ud O-deethylase, and benzo(a)pyrene monooxygenase activities\ud in the combined PCB and CPFA-fed trout were significantly\ud higher than in controls and CPFA-fed fish,\ud and significantly lower than in PCB-fed fish. There\ud was no significant difference in cytochrome P450 levels\ud after week 5.\ud This is the first time dietary PCBs have been\ud shown to induce the MFC system in PCB-fed rainbow\ud trout