Induction of fish vitellogenin and alterations in testicular structure: preliminary results of estrogenic effects in chub (Leuciscus cephalus)

Laboratory and field studies were carried out in order to assess, in a common cyprinid freshwater fish, the chub (Leuciscus cephalus), the feasibility of biological methods to detect and quantify estrogenic effects. In the laboratory the effects of 17beta estradiol were investigated on Vitellogenin (Vtg) induction and on testis organisation. Vtg was quantified by immunodetection using an established ELISA for carp (Cyprinus carpio) Vtg. Estradiol exposure resulted in a significant and rapid increase in plasma Vtg in both male and female chub, indicating that vitellogenic response in the chub is sensitive to estrogen(s). Histological examination of the testis in males exposed to estradiol also showed effects on the testis. Preliminary field studies on wild chub showed that fish living in a polluted river had elevated concentrations of plasma Vtg and had some alterations in the testis compared with wild fish from a reference site. Together these preliminary laboratory and field results show that chub could be an interesting fish species for further studies of biological effects of environmental estrogens in the aquatic environment. / La faisabilité de la mesure de vitellogénine et de l'interprétation des coupes histologiques de gonades mâles a été étudiée sur le chevaine (Leuciscus cephalus). Au laboratoire, l'exposition de chevaines adultes à l'oestradiol entraîne une très forte induction de vitellogénine ainsi que des effets significatifs en terme d'altération des gonades mâles (nécroses, désorganisation de la structure tubulaire, prolifération des cellules de Sertoli). Ces premiers résultats ont été suivis par une phase d'expérimentation sur le terrain.