Novel aspect of neuroendocrine effects of 2,4,6-trinitrotoluene on European eel (Anguilla anguilla L, 1758)

Brain estrogen receptor (ER), P450 aromatase (CYP19), steroidogenic acute regulatory (StAR) protein and the P450-mediated cholesterol side chain cleavage (P450scc) enzyme and plasma cortisol level were investigated as potential biomarkers for assessing the endocrine disrupting properties TNT on European eel. Fish were exposed for 6 and 24h to 0.5, 1 and 2.5mg/L nominal concentration of TNT and ER, CYP19, StAR protein and P450scc gene expressions were measured in brain using real-tine PCR. Plasma cortisol levels were determined by a time-resolved fluoroimmunoassay. TNT exposed eels showed a decrease of StAR and P450scc mRNA expressions compared to controls. The TNT effect on the StAR protein and P450scc expression paralleled low plasma levels of cortisol. A concentration-specific increase of CYP19 was also observed in TNT exposed eels. The overall results suggest that the exposed eels are experiencing a TNTmediated alteration of their neuroendocrine system. Particularly, TNT produced an impairment of the initial neurosteroidogenic phase resulting to a potential decrease of plasma cortisol at 24h of exposure.