Evaluating Estrogenic Effect Of Endocrine Disrupting Chemicals (Edcs) By Using Zebrafish(Danio Rerio) Embryo As A Model

The harmful effects of endocrine disrupting chemicals (EDCs) on humans and wildlife have attracted widespread attention. With the exposure tests of some typical EDCs such as natural estrogen17(β-estradiol(E2), estriol(E3), synthetic hormones including diethylstilbestrol(DES),4-octyl phenol(OP), bisphenol A(BPA), tamxifen(TMX) and3-(2,3-dibromopropyl) isocyanurate(TBC), and investigating their effects on inducing VTG spatial and temporal expression in zebrafish embryos, zebrafish embryos was investigated to be used as a model in analyzing and assessing endocrine disruption effects of compounds.The results revealed that E2can obviously induce VTG expression of zebrafish embryos, compared with the control. The induction was dose-depended.0.5×μM E2cannot induce VTG expression during early life stages of zebrafish embryos, but the expression of VTG gene can be detected significantly in zebrafish embryos after144hpf. In situ hybridization studies indicated that VTG expression cannot be observed in the control, Expression of VTG gene can be detected in liver and heart of some samples exposed by0.5μM E2for4d to7d, and the positive expression rates were12.50%,39.13%,89.36%and100%respectively.E2, E3, DES and OP can induce VTG expression of zebrafish embryos in dose-dependent manner, which manifest their estrogenic effects in varying degrees. The lowest observable effect concentration (LOEC) of E2, E3, DES and OP were1.25×10-2、1.46、1.65×10-4、and1.35respectively. Single exposure of BPA,TMX and TBC had no significant effect on expression of VTG gene in zebrafish embryos; whereas it was showed that co-exposeure of either TMX or TBC with E2can significantly inhibit increase of VTG gene expression. In situ hybridization results of TBC co-exposure test were consistent with QT-PCR results. The VTG gene was only expressed in the heart and liver of the embryos in0.5M E2exposure group. The result clearly showed that it is relatively specified and sensitive to use zebrafish embryos as a model to screen the estrogenic chemicals. It can be concluded that VTG expression in zebrafish embryos can also be served as a biomarker to analyze and assess endocrine disrupting of compounds. Zebrafish embryos can be used as a model organism to carry out the estrogenic effects of endocrine disrupting chemicals.