Abstract :
[en] Endocrine disruptors are known to alter endogenous free and/or esterified levels of androgenic and estrogenic steroid hormones in aquatic molluscs. However, there is still a controversy on the origin of steroids in these animals. In this study, free and esterified testosterone concentrations were measured in the hermaphroditic aquatic gastropod Lymnaea stagnalis exposed to molecules known for their androgenic (testosterone and tributyltin), anti-androgenic (cyproterone-acetate) and estrogenic (chlordecone) properties by reference to their mode of action in vertebrates. In parallel, snail oviposition and fecundity were followed over the 21-day exposure period. Testosterone exposure resulted in increased esterified testosterone levels whereas free testosterone concentrations remained stable. In contrast, cyproterone-acetate increased significantly the free form of testosterone with no changes in the esterified form whereas chlordecone showed a tendency to reduce, though not significantly, esterified testosterone concentrations without changes in free testosterone levels. Finally, tributyltin did not alter testosterone homeostasis. The production of egg-clutches and eggs was significantly reduced only in the snails exposed to the highest concentrations of chlordecone (19.6 µg/L) and tributyltin (94.2 ng Sn/L). Overall, this study demonstrates that uptake of testosterone from the exposure medium occurs in L. stagnalis. Moreover, it shows that cyproterone-acetate and, to a lesser extent, chlordecone can alter endogenous testosterone levels in this freshwater snail. However, relationship between hormonal changes and snail reproduction has not been established.
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