EFFECTS OF DIETARY IRON CONCENTRATIONS ON THE CYTOCHROME-P450 SYSTEM OF ATLANTIC SALMON (SALMO-SALAR)

Groups of Atlantic salmon (Salmo salar) parr were fed a basal diet con taining 27 mg Fe-kg feed-1 supplemented with different iron levels (0, 80, and 160 mg.kg-1, respectively) for 8 wk. After this period, a sub group of each iron regime was treated intraperitoneally with beta-naph thoflavone (BNF), a potent inducer of cytochrome P450 1A1 in fish. Dif ferences between the iron regimes were observed in hepatic iron conten t, which was higher in the high-iron group, and in P450 1A1 levels and monooxygenase activity, measured as 7-ethoxyresorufin 0-deethylase (E ROD), which were lower in the high-iron group. Differences were also o bserved in the induction response of P450 1A1 and EROD to BNF. Levels of a constitutive isozyme denoted P450con, belonging to the P450 3A su bfamily, did not respond to the dietary iron in the same manner, demon strating selective regulatory effects of iron on different P450 isozym es.