Juvenile sea bass biotransformation, genotoxic and endocrine responses to beta-naphthoflavone, 4-nonylphenol and 17 beta-estradiol individual and combined exposures.
Juvenile sea bass, Dicentrarchus labrax L., were exposed during 2, 4, 8, and 24 h to 0.9 microM beta-naphthoflavone (BNF), 131 nM 17 beta-estradiol (E(2)), 4.05 microM 4-nonylphenol (NP), as well as to BNF combined either to E(2) or NP (maintaining the previous concentrations). Liver cytochrome P450 content (P450), ethoxyresorufin-O-deethylase (EROD), and glutathione S-transferase (GST) activities were measured in order to evaluate biotransformation responses. Genotoxicity was assessed as erythrocytic nuclear abnormalities (ENA) frequency. The effects on endocrine function were evaluated as plasma cortisol and glucose. Cortisol was not affected by xeno/estrogens tested, either in single exposure or mixed with BNF. Nevertheless, the intermediary metabolism was affected since glucose concentration increased after 4 h exposure to E(2), and after all BNF+NP exposure lengths. Moreover, a synergism between BNF and NP was thoroughly demonstrated, whereas a sporadic antagonistic interaction was found at 4 h BNF + E(2) exposure. Liver EROD and GST activities were not significantly altered by single E(2) or NP exposure. However, both compounds were able to induce EROD activity in the presence of BNF. NP single exposure was able to significantly increase liver P450 content, while its mixture with BNF displayed an antagonistic interference. Considering the xeno/estrogens single exposures, only NP induced an ENA increase; however, both mixtures (BNF + E(2) and BNF + NP) displayed genotoxic effects. Fish responses to mixtures of xenobiotics are complex and the type of interaction (synergism/potentiation or antagonism) in a particular mixture can vary with the evaluated biological response.
Department of Biology, Aveiro University, Campus de Santiago, 3810-193 Aveiro, Portugal.
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D000818:Animals; D001492:Bass; D001711:Biotransformation / Q000187:drug effects; D019363:Cytochrome P-450 CYP1A1 / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004357:Drug Synergism; D004703:Endocrine System / Q000187:drug effects*; D004781:Environmental Exposure; D004791:Enzyme Inhibitors / Q000009:adverse effects; D004912:Erythrocytes / Q000187:drug effects*; D004958:Estradiol / Q000633:toxicity; D005982:Glutathione Transferase / Q000187:drug effects*; D008099:Liver / Q000187:drug effects* / Q000201:enzymology; D010636:Phenols / Q000633:toxicity; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000378:metabolism / Q000633:toxicity*; D019324:beta-Naphthoflavone / Q000633:toxicity
D004791:Enzyme Inhibitors; D010636:Phenols; D014874:Water Pollutants, Chemical; D004958:Estradiol; D019324:beta-Naphthoflavone; D003577:Cytochrome P-450 Enzyme System; D019363:Cytochrome P-450 CYP1A1; D005982:Glutathione Transferase; C041594:4-nonylphenol