Effects of (anti)estrogenic and (anti)androgenic prototype chemicals on carp reproductive activity

The effects on gonad morphology, sex steroid and vitellogenin (VTG) plasma levels were investigated in k2 carps exposed to graded concentrations of tamoxifen, ethynyl-oestradiol (EE2), flutamide and methyl-dihydro-testosterone (MDHT), four chemicals chosen as prototype of anti-estrogenic, estrogenic, anti-androgenic and androgenic activities, respectively. Fish were treated for 14 days under flow-through conditions. At the end of the exposure, blood was taken from the caudal vein and plasma was analyzed for biomarkers and sex steroids: oestradiol-17β (E2) and testosterone (T) for females, T and 11-ketotestosterone (11KT) for males. Gonad and liver fragments were fixed in Bouin’s fluid for histological examination. No significant morphological alterations of the gonads were observed in carps exposed to tamoxifen; at the highest concentration tested (540μg/l); T and 11-KT significantly increased in males (P<0.01), while T and E2 decreased in females. Other effects, such as increased number of melanomacrophage centers, vacuolated hepatocytes, enlarged hepatic blood vessels, altered structure of the hepatic duct walls, and depletion of glycogen deposits, could be better related to tamoxifen as a toxicant rather than an endocrine disrupter. Males exposed to EE2 showed testes with evidence of disrupting activity (reduction of spermatogenic cysts, fibrous and amorphous tissue amongst lobules). A significant decrease of both T and 11-KT was also observed in these same fish, together with a strong dose dependent increase of VTG levels. Both males and females showed gonad morphological alterations when exposed to flutamide. In females, atresia of previtellogenic oocytes and stroma alteration were observed starting from the lowest concentration (2 μg/l). At the highest concentration (700μg/l), T and E2 decreased in females and both androgens significantly decreased in males. This study is part of a wider research aimed to collect samples for detection and identification of known and new biomarkers for Endocrine Disrupters.