Effect of Benzo(a)pyrene on Hepatic Biotransformation Activities: Time Course of Induction in Aquaculture European Sea Bass (Dicentrarchus labrax)

The responses of phase I and phase II enzymes to benzo(a)pyrene (BaP) exposure were characterized in liver of fish farm European sea bass (Dicentrarchus labrax). Treatment of sea bass with BaP by intraperitoneal injection produced a rapid putative MFO induction. Highest ethoxyresorufin-O-deethylase (EROD), ethoxycoumarin-O-deethylase (ECOD) and benzo(a)pyrene monooxygenase (BaPMO) activities were observed in microsomes 14–24 h after BaP injection. EROD was induced 14.5 fold, ECOD 3.9 and BaPMO 13 fold. Spectrophotometrically measured microsomal cytochrome P-450 and NADPH-cytochrome c reductase activity were not induced by BaP injection, whereas a low increase in cytochrome b₅ level was observed (induction factor 1.6 fold). Induction of phase II enzyme activities was lower than that of phase I enzymes: microsomal uridine diphospho-glucuronyl transferase (UDPGT) and cytosolic glutathion-S-transferase (GST) were induced 3.9 and 1.5 fold, respectively. The results indicate that sea bass is a sensitive species with respect to exposure to polycyclic aromatic hydrocarbons, exhibiting early marked responses of phase I and phase II biotransformation enzymes. The species offers potential as a tool for both laboratory studies and pollution monitoring. In the latter context it could be employed in the fish farms that occur alongside coastal regions.