Acute sublethal effects of 2,4,6-trinitrotoluene (TNT) on the European eelAnguilla anguilla(Linnaeus, 1758)

Abstract

The aim of this study is to investigate the effects of the explosive 2,4,6-trinitrotoluene (TNT) on liver phase I and II biotransformation enzymes at gene (CYP1A1, GST and UDPGT) and catalytic levels by investigating EROD, GST and UDPGT activities, on crucial brain steroidogenic proteins (StAR and P450scc genes expression) and on gills histology in a model fish species such as the European eel (Anguilla anguilla, Linnaeus, 1758). Eels were exposed in vivo for 6 and 24 hours to 0.5mg/L, 1mg/L and 2.5mg/L nominal concentration of TNT by using 0.1‰ of DMSO as a carrier. The TNT produced a significant inhibition of EROD activity and an increase of UDPG T and GST genes expression and activities compared to controls. A decrease of StAR and P450scc genes was also observed in TNT exposed eels. Finally concerning gills, branchial lifting was evident at the lowest TNT concentration (0.5 mg/L) while lamellar aneurisms, vascular congestion, hypertrophy and hyperplasia of the epithelium were evident at 2.5 mg/L. Our results highlighted the concern related to the release of TNT on the seabed: the inhibition of EROD activity may result in an increased susceptibility of the organism to P450 inducers such as dioxins and PAH. TNT also seems to affect fish neurosteroidogenesis by downregulating key enzymes (StAR and P450scc genes). Gills seem to be a target organ for TNT in fish. The present research provided relevant information on TNT metabolism/toxicity and indicated sensitive targets of TNT toxicity in fish species.