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

Abstract Nitroaromatics may be metabolized both to reactive electrophiles and to mediators of reactive oxygen species (ROS) formation. Hepatic effects of nitroaromatic compounds were investigated in three species of flatfish. No changes were seen in 7-ethoxyresorufin O -deethylase (EROD) activity in turbot ( Scophthalmus maximus ) exposed (i.p. 48 h) to either 1-nitropyrene or nitrofurantoin, indicating non-induction of cytochrome P4501A. Similarly, no changes were seen in any antioxidant enzyme activities (superoxide dismutase, catalase, glutathione peroxidase, DT-diaphorase, aldehyde dehydrogenase). DNA oxidative damage was indicated to be a widespread endogenous phenomenon by the presence of 8-hydroxydeoxyguanosine (8OHdG) in liver of S. maximus , dab ( Limanda limanda ) and sole ( Solea solea ). No increase in 8OHdG levels were seen in S. maximus, L. limanda or S. solea exposed to nitrofurantoin. The results for 8OHdG were in contrast to those reported for English sole ( Parophrys vetulus ) which showed an increase in hepatic levels following similar nitrofurantoin treatment (Nishimoto et al., 1991). 32 P-post-labelling analysis of liver from exposed S. maximus showed no evidence of DNA adducts with chomatographic conditions able to detect 1-nitro-pyrene-derived DNA adducts in rat. None of the various parameters studied appear to be suitable as biomarkers for the detection of exposure to nitroaromatics in the aquatic environment.