Catalytic and immunochemical properties of hepatic cytochrome P450 1A in three avian species treated with beta-naphthoflavone or isosafrole

Induction of cytochrome P450 IA (CYP1A) can be used as a biomarker of expos ure to planar halogenated aromatic hydrocarbons (PHAHs). Our objective was to characterize the induction of CYP1A activity and protein in three avian species following in vivo treatment with beta -naphthoflavone (BNF) and/or isosafrole. Alkoxyresorufin-O-dealkylase (alk-ROD) activities of hepatic mi crosomes from Herring Gulls (Larus argentatus) (HGs), Double-crested Cormor ants (Phalacrocorax auritus) (DCCs) and chickens (Gallus domesticus) were m easured using ethoxy-, methoxy-, pentoxy- and benzyloxy-resorufin, in the p resence and absence of the inhibitors ellipticine or furafylline. Immunorea ctivity of microsomal proteins with antibodies to several CYP1A proteins wa s investigated. CYP1A protein and alk-ROD activities of HGs and DCCs. but n ot chickens, were induced by isosafrole. Ellipticine was a potent and non-s elective inhibitor of alk-ROD activity in all three species, while furafyll ine inhibition of alk-ROD activities varied among species and treatments. I n all three species, BNF induced a protein immunoreactive with monoclonal a ntibody to CYP1A1 from the marine fish Stenotomus chrysops (scup), but a CY P1A2-like protein was not detected in avian microsomes probed with polyclon al antibodies to mouse CYP1A2. Variations in responses among avian species indicate that CYP1A proteins and substrate specificities should be characte rized for each species used in PHAH biomonitoring programs. (C) 2001 Publis hed by Elsevier Science Inc.