Endocrine disruption effects of p, p′-DDE on juvenile zebrafish

The persistent organic pollutant p,p-DDE, the major metabolite of the insecticide DDT, has displayed evidence of endocrine disruption through the inhibition of androgen binding to androgen receptors in different species. Although p,p-DDE was continuously detected in wild fish with abnormal gonad development such as intersex, little is known about its mode of action during gonad development in fish. To elucidate the potential endocrine effects of this pollutant in zebrafish (Danio rerio), juveniles (30days post hatch) were exposed to p,p-DDE during the critical window of sexual differentiation. Fish were exposed to sublethal concentrations ranging from 0.01 to 20 mu gl(-1) over 14days and were maintained in control water for an additional 4months. As core endpoints, the vitellogenin (vtg) concentration was measured at the end of exposure, and sex ratio and the gonadosomatic index were assessed 4months after the end of exposure. An increase in vtg production in whole body homogenate was observed in fish exposed to 0.2 and 2.0 mu gl(-1) p,p-DDE. No significant differences were displayed in morphological parameters such as the gonadosomatic index of males and females or sex ratio. However, exposed females presented histopathological changes that include the reduction of the number of mature oocytes, which might impair their successful reproduction. These results demonstrate the ability of p,p-DDE to cause endocrine disruption in zebrafish exposed during gonad differentiation of juvenile specimens. Furthermore, vtg induction by p,p-DDE in juvenile zebrafish arises as a predictive marker for adverse effects of this DDT metabolite on the ovarian function of female zebrafish. Copyright (c) 2014 John Wiley & Sons, Ltd. Potential endocrine effects of p,p'-DDE, the major metabolite of the insecticide DDT, were investigated in zebrafish during gonad differentiation. Juveniles were exposed to sub-lethal concentrations during 14 days and maintained in control water for further 4 months. An increase in vtg production was observed in exposed juveniles. Female gonads presented histopathological changes, which might impair their successful reproduction. These results demonstrate the ability of p,p'-DDE to cause endocrine disruption during gonad differentiation of zebrafish.