Juvenile sea bass liver P450, EROD induction, and erythrocytic genotoxic responses to PAH and PAH-like compounds

Sea bass were exposed, for 0, 2, 4, 6 and 8 h, to 0 or 2.7 muM P-naphthoflavone (BNF), or to 0, 0.1, 0.3, 0.9, or 2.7 muM benzo[a]pyrene (B(a)P) and naphthalene (NAPH).'Liver cytochrome P-450 content (P450) and liver ethoxyresorufin-O- deethylase activity (EROD) induction were determined as phase I biotransformation responses, whereas erythrocytic micronuclei (EMN) and erythrocytic nuclear abnormalities (ENA) tests were performed to assess genotoxic effects. Liver alanine aminotransferase activity and liver somatic index were determined ' respectively, as liver damage and common health indicators., A significant increase in sea bass EROD activity began, respectively, at 2 and 4 h exposure to 2.7 muM B (a) P and 2.7 muM BNF, whereas NAPH failed to induce EROD activity. Maximal EROD activity was observed after 6 It exposure to 2.7 muM BNF (9-fold increase), 2.7 muM B(a)P (4-fold increase), and 12.7 PM NAPH (2-fold increase), indicating BNF as the most potent EROD inducer (BNF > B(a) P > NAPH). A significant increase in liver P450 content was observed at 6 h exposure to 2.7 muM BNF (6.5-fold increase), indicating BNF as the most potent P450 inducer. A significant P450 increase was observed at 8 h exposure only to 0.1 muM B(a)P (2-fold increase), whereas it slightly increased at 2 h exposure to 2.7 muM NAPH, within a wide variable range. The BNF, NAPH, and B(a)P genotoxic potential was demonstrated as sea bass EMN and ENA. B(a)P promoted at 2h exposure a significant EMN (24-fold) and ENA (2.2401d) increase, whereas NAPH exhibited similar results only at 8 h exposure. BNF also increased significantly sea bass EMN (8fold) and ENA (1.5-fold) after 8 h. The results indicated B (a) P as the most genotoxic compound, followed by NAPH and BNF (B(a)P>NAPH>BNF). Despite the low liver P450content and EROD activity induction by NAPH and B(a)P, their genotoxic potential was higher than that of BNF. (C) 2002 Elsevier Science (USA).