Histopathological effects of cocaine on the European eel (Anguilla anguilla) ovary.

Cocaine (COC) is an illicit drug widespread in surface waters, in concentrations ranging from μg.L-1 to ng.L-1. The presence of cocaine in the environment represents a potential risk for aquatic organisms, but the ecological effects are still poorly understood. More recently, in the European eel (Anguilla anguilla) it has been demonstrated that cocaine accumulates into tissues generating serious injury in skeletal muscle. It also affects the gill epithelium and increases plasma levels of cortisol and prolactin after exposure to environmental concentrations of COC (20 ng.L-1).The aim of this study was to evaluate the influence of environmental relevant concentration of cocaine (20 ng.L-1) on the morphological development of eel ovaries and to immunolocalize enzymes as 3β-HSD, 17β-HSD and P450 aromatase involved in the synthesis of two sex hormones: testosterone and 17β-estradiol. Compared to controls, cocaine-exposed animals showed a smaller follicles area and a higher percentage of connective tissue; the histological analyses showed that the control specimens exhibited numerous full vitellogenic oocytes (fvOo) and early vitellogenic oocytes (evOo), while the exposed animals frequently showed previtellogenic oocytes (pOo); moreover, in the ovary of control animals, a strong presence of 3β-HSD, 17β-HSD and P450 aromatase was observed. Our results show that even a low environmental concentration of cocaine is able to affect the morphology and the enzymatic response of the ovaries of A. anguilla. Thus, considering the complex life cycle of the eel, the changes observed in the ovary could threaten the reproduction of the eel and potentially affect the survival of this species.