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Induction of cytochrome P450‐associated monooxygenases in northern leopard frogs, Rana pipiens , by 3,3′,4,4′,5‐Pentachlorobiphenyl
Author(s) -
Huang Yuewern,
Melancon Mark J.,
Jung Robin E.,
Karasov William H.
Publication year - 1998
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.5620170818
Subject(s) - monooxygenase , leopard frog , cytochrome p450 , corn oil , biology , cytochrome , microsome , unspecific monooxygenase , ecotoxicology , polychlorinated biphenyl , rana , medicine , endocrinology , chemistry , enzyme , toxicology , metabolism , biochemistry , ecology
Northern leopard frogs ( Rana pipiens ) were injected intraperitoneally either with a solution of polychlorinated biphenyl (PCB) 126 in corn oil at a concentration of 0.2, 0.7, 2.3, or 7.8 mg/kg body weight or with corn oil alone. Appropriate assay conditions with hepatic microsomes were determined for four cytochrome P450‐associated monooxygenases: ethoxyresorufin‐ O ‐dealkylase (EROD), methoxy‐ROD (MROD), benzyloxy‐ROD (BROD), and pentoxy‐ROD (PROD). One week after PCB administration, the specific activities of EROD, MROD, BROD, and PROD were not elevated at doses ≤0.7 mg/kg ( p > 0.05) but were significantly increased at doses ≥2.3 mg/kg compared to the control groups ( p < 0.05). The increased activities of these four enzymes were 3 to 6.4 times those in the control groups. The increased activities were maintained for at least 4 weeks. Because of a lack of induction at low doses of PCB 126, which were still relatively high compared to currently known environmental concentrations, we suspect that EROD, MROD, BROD, and PROD activities are not sensitive biomarkers for coplanar PCB exposure in leopard frogs.