BIOTRANSFORMATION ENZYMES AND THEIR INDUCTION BY BETA-NAPHTHOFLAVONE IN ADULT SEA BASS (DICENTRARCHUS-LABRAX)

In the present study we have determined for the first time the hepatic activities of several microsomal P-450 dependent monooxygenases inclu ding the testosterone hydroxylase and the Ah-receptor gene battery-rel ated phase II enzymes [UDP-glucuronyl transferase (UDP-GT), DT-diaphor ase, glutathione S-transferase, aldehyde dehydrogenases] in adult sea bass (300-400 g). We also investigated the effect of beta-naphtoflavon e (beta-NF) on these enzymes to assess their potential as biomarkers o f polycyclic aromatic hydrocarbon exposure. beta-NF. administered to f ish with a single i.p. injection at various doses, resulted in an indu ction in the liver of the P-450 1A, as immunodetected by anti rat P-45 0 1A1 antibodies, P-450 1A-linked ethoxyresorufin-O-deethylase (EROD) and methoxyresorufin-O-demethylase (MEROD) activities. Among the phase II enzymes only the phenol UDP-GT was induced in liver by beta-NF. Th e time course of these inductions exhibited different patterns. EROD a nd MEROD activities reached a peak value 3 days post-injection and mai ntained values significantly above the corresponding control activitie s over the 30 days of the experiment, the phenol UDP-GT activity peake d at dap 8 and afterwards declined rapidly achieving the control value 18 days post-injection. A treatment of 80 mg kg(-1) beta-NF increased the immunodetectable P-450 1A apoprotein and EROD, but not MEROD, act ivity in extrahepatic tissues such as, gill, kidney and olfactory rose ttes. Taken overall, the results indicate that MEROD. EROD and phenol UDP-GT activities may be useful biomarkers for the exposure of adult s ea bass to polycyclic aromatic hydrocarbons. (C) 1998 Elsevier Science B.V. All rights reserved.