NORMAL STATUS OF HEPATIC 7-ETHOXYRESORUFIN O-DEETHYLASE (EROD) ACTIVITY, ANTIOXIDANT ENZYMES AND DNA OXIDATION IN TURBOT (SCOPHTHALMUS-MAXIMUS) AND OTHER FLATFISH SPECIES FOLLOWING EXPOSURE TO NITROAROMATIC COMPOUNDS

Nitroaromatics may be metabolized both to reactive electrophiles and t o mediators of reactive oxygen species (ROS) formation. Hepatic effect s of nitroaromatic compounds were investigated in three species of fla tfish. No changes were seen in 7-ethoxyresorufin O-deethylase (EROD) a ctivity in turbot (Scophthalmus maximus) exposed (i.p. 48 h) to either 1-nitropyrene or nitrofurantoin, indicating non-induction of cytochro me P4501A. Similarly, no changes were seen in any antioxidant enzyme a ctivities (superoxide dismutase, catalase, glutathione peroxidase, DT- diaphorase, aldehyde dehydrogenase). DNA oxidative damage was indicate d to be a widespread endogenous phenomenon by the presence of 8-hydrox ydeoxyguanosine (80HdG) in liver of S. maximus, dab (Limanda limanda) and sole (Solea solea). No increase in 80HdG levels were seen in S. ma ximus, L, limanda or S. solea exposed to nitrofurantoin. The results f or 80HdG were in contrast to those reported for English sole (Parophry s vetulus) which showed an increase in hepatic levels following simila r nitrofurantoin treatment (Nishimoto et al., 1991). P-32-post-labelli ng analysis of liver from exposed S. maximus showed no evidence of DNA adducts with chomatographic conditions able to detect 1-nitropyrene-d erived DNA adducts in rat. None of the various parameters studied appe ar to be suitable as biomarkers for the detection of exposure to nitro aromatics in the aquatic environment. Copyright (C) 1996 Elsevier Scie nce Ltd