Long Term Estrogenic Effects Of Bisphenol A And Nonylphenol On The Development And Reproduction Of Zebrafish (Danio Rerio)

Bisphenol A(BPA) and NonylphenoI(NP) are known as endocrine disrupters having the estrogenic effect. When they are dissolved in the water, they can interfere fishes' normal endocrine level. The present researches about this area are focused on the subacute effect, but the data about chronic exposure are few. In the nature condition, the effect of endocrine disrupters on fish continues for a long time including the development and reproduction time. So the research of chronic toxicity is closer to the real condition and can helps people understand mechanism of the environmental estrogens' physiological and ecological effect on fish.The zebrafish (Danio rerio), a member of the family Cyprinidae and native to India and Pakistan, has, during the last decade, been intensively used as an experimental animal for biological and biotechnological research. In addition, the zebrafish is a species routinely employed in the Organization of Economic Cooperation and Development(OECD) toxicity tests.To investigate the effect of Bisphenol A and Nonylphenol on the fishes' development, sexy ratio, reproductive ability and quality of offspring, Zebrafish was used as a kind of model animal in this paper.The 48-hour-old eggs were exposed to bisphenol A at 200,500,1000μg/L, to nonylphenol at 30 μg/L and to their mixture until 90dph. Then the samples were randomly selected to determine their sex. Testis were fixed and then embedded in paraffin, sectioned at 6～8μm thickness and H-E stained in order to further determine gonad development. 1000μg/L bisphenol A and all mixture of bisphenol A and nonylphenol can interfere the endocrine level in the zebrafish so seriously as to restrain their growth. Bisphenol A could led to feminization at 500μg/L, moreover bisphenol A could restrain the development of gonad at 1000μg/L so that the ratio of undevelopment raised in the hole colony. But there was no data which could prove that such suppression was synergism action led by the joint exposure of nonylphenol and bisphenol A.At 120dph, sexually mature zebrafishes were randomly selected from every group. To investigate the effects of bisphenol A, nonylphenol, and their mixture on the reproductive ability and offspring quality of zebrafish, every two females and one male were placed in a glass tank. Compared with control group, zebrafish's reproductive ability could be suppressed by the bisphenol A and NP. The interaction of bisphenol A and nonylphenol could very significantly suppress the reproduction of zebrafish. The malformation ratio in the F2, which were reproduced from the F1 exposed to bisphenol A, raised. Bisphenol A prolonged the eggshell breaking time and survival days under starvation of F2 at 200,500μg/L. Whereas it had opposite effect at 1000μg/L. Bisphenol A and nonylphenol could significantly affected reproductive ability and offspring quality of zebrafish. The interactions of them are synergism action.After the exposure lasted for two generation, the F2 from the F1 exposed to the high level bisphenol A were more sensitive. At the same concentration(BPA500,1000 μg/L) and the exposure time, the vtg in zebrafish reproduced from F1 exposed to the high level bisphenol A was higher by ELISA.