Effect of diet on the responses of hepatic biotransformation enzymes to benzo(a)pyrene in the European sea bass ( Dicentrarchus labrax)

Abstract

l. In order to investigate how nutritional environmental factors can affect the regulation and responses to biotransformation enzymes to organic xenobiotic exposure in fish, we fed sea bass ( Dicentrarchus labrax) two different commercial diets, one devoid of and one containing fish oil (diet A and B, respectively). 2. After five months on each diet, fish were treated with benzo(a)pyrene (BaP) by intraperitoneal injection, and the responses of hepatic biotransformation enzymes determined 14hr later. 3. Responses to BaP treatment were marked in fish on diet B, viz. increases in microsomal contents of cytochromes P-450 and b 5 (respectively 2.7 and 2.3 fold) and activities of 7-ethoxyresorufin- O-deethylase (EROD), 7-ethoxycoumarin- O-deethylase (ECOD) and BaPmonooxygenase (BaPMO) (14.5, 2.9 and 32.9 fold). In contrast, microsomal EROD, ECOD and BaPMO activities were lower in fish fed diet A and the induction response was less marked for EROD microsomal (4.2) and BaPMO (11.4) and absent for ECOD activities. 4. Similarly, the phase II conjugase, uridine diphosphoglucuronyl transferase (UDPGT) activity, was induced less in fish fed diet A than diet B, viz. respectively 2.3 and 5 fold increase. No induction of cytosolic glutathione- S-transferase was observed in either treated condition. 5. The results indicate that the fatty acid composition of diet of sea bass can affect significantly the biotransformation enzymes responses to xenobiotic pollutants. Such effects should be taken into account when using such responses and species in monitoring the impact of organic pollution.