Vitellogenic responses of 17β-estradiol and bisphenol A in male Chinese loach (Misgurnus anguillicaudatus)

In this study, male Chinese loaches were exposed to 17β-estradiol (E2), bisphenol A (BPA) and their mixtures, respectively, for 42 days using a semi-static exposure system. Plasma vitellogenin (Vtg) in male Chinese loaches was used as the determining endpoint. The results demonstrated that male Chinese loaches were sensitive to E2, and the vitellogenic responses showed time- and dose-dependent increase. Similarly, BPA induced the estrogenic effects in male Chinese loaches, and the vitellogenic response increased in a time- and dose-dependent manner. The synthesis of Vtg was initiated by the exposure to higher level of BPA (500 μg/L) within 7 days, and a relative long-term exposure to lower concentrations of BPA (10-100 μg/L) also led to the production of Vtg. The estrogenic effect of the binary mixture of E2 and BPA also showed a time- and dose-dependent response, which was more potent than that of individual compounds, and Vtg contents in the binary mixture group were higher than the summation of Vtg contents in the single-compound groups at the same concentration.