Effects of xenoestrogens on the expression of vitellogenin (vtg) and cytochrome P450 aromatase (cyp19a and b) genes in zebrafish (Danio rerio) larvae

摘要

In the present study, expression levels of vitellogenin (vtg) and cytochrome P450 aromatase genes (cypl9a and cypl9b) in zebrafish larvae during the early stages of development were investigated by quantitative real time-PCR assay. The results indicated that vtg gene transcription was induced seven days after zebrafish larvae fertilization, whereas the expression of cyp19a and cypl9b genes was detected as early as 3 and 4 days post-fertilization (dpf). Investigations into the effects of 17β-estradiol (E2) exposure on the expression of these genes showed that both vtg and cyp19b were upregulated by E2 in zebrafish larvae as early as four dpf, whereas no variation was observed in cypl9a gene expression. The estrogenic potential of pharmaceutical estrogen (DES), phenol estrogen (BPA) and the brominated flame retardants, TBBPA, DE-71 and 4-BP, were evaluated by analyzing the expression of these three genes in zebrafish larvae. The results demonstrated that natural estrogen, endocrine disrupting compounds and brominated flame retardants act as endocrine disrupters through different mechanisms. We have demonstrated for the first time that the polybrominated diphenyl ether mixture, DE-71, acts as an endocrine disrupter by upregulation of cypl9b gene expression at a relatively low concentration. These results indicate that analysis of vtg and cypl9b gene expression in zebrafish during early embryogenesis and organogenesis represents the basis of a sensitive and fast bioassay for the routine assessment of xenoestrogen effects.