title: Induction of in vitro EROD activity and in vivo caffeine metabolism in two species of New Zealand birds.
abstract: In birds, induction of cytochrome P4501A (CYP1A) is usually assessed as liver microsomal ethoxyresorufin O-deethylase (EROD) activity, but in mammals, it can be determined by a caffeine metabolism blood test. We investigated both of these measures in two species of New Zealand birds. Administration of a model CYP1A inducer, β-naphthoflavone (BNF) (80mg/kg i.p. twice 2 days apart), to paradise shelducks (Tadorna variegata; herbivore) and southern black-backed gulls (Larus dominicanus; omnivore) (n=5 or 6) caused marked increases in EROD activity (80- and 20-fold, respectively). In both species, BNF treatment also caused significant increases (>8-fold) in caffeine metabolism determined prior to sacrifice as the serum concentration ratio of the major metabolite, paraxanthine, to caffeine, after caffeine administration (1mg/kg i.p.). The results suggest in vivo caffeine metabolism is a potentially useful non-destructive biomarker of CYP1A induction in wild birds.
authors.affiliation: School of Pharmacy, University of Otago, PO Box 913, Dunedin, New Zealand.
authors.forename: Mihoko
authors.initials: M
authors.lastname: Numata
authors.forename: J Paul
authors.initials: JP
authors.lastname: Fawcett
authors.forename: Rhonda J
authors.initials: RJ
authors.lastname: Rosengren