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Environmental endocrine disruptors means entering vivo, can interfere with endocrine substances synthesis, release, transport, metabolism and other processes, activate or inhibit the function of the endocrine system, destroy the stability of the internal environment can lead to reproductive problems, birth defects, developmental abnormalities , metabolic disorders, and certain cancers. Nonylphenol (NP) and bisphenol A (BPA) is a widespread environmental endocrine disruptors in water, affecting fish reproduction and development. Has been reported that endocrine disruptors on animals had an impact on the structure of the testis, as can reduce sperm quality, semen volume decreased sperm unite, there oocytes, testis fibrosis degradation. But for NP and BPA molecular mechanisms regulating testicular development and testicular structure and molecular mechanisms of combining little research. Under natural conditions, fish testis development by sex hormone regulation 11 - keto testosterone (11-KT) and 17p estradiol (E2) synthesis of the major sex hormones testis. Same with other vertebrates, fish gonadal hormone synthesis and transformation by cytochrome P450 enzymes catalytic regulation. P45011p hydroxylase (CYP11B), P450 aromatase (CYP19A) is a 11-KT and E2 synthesis of a key enzyme, therefore, quantitative study of NP and BPA on gonadal expression of cytochrome P450 enzymes, is to reveal the environmental endocrine disruptors on Mechanism of fish gonad important way. This paper studies the hormone synthase gene expression case study of environmental endocrine disruptors NP and BPA on sperm development and pathways affected testis structure in order for the biomarker screening and provide the necessary environmental assessment ecotoxicological data. However, the wild water environment is more complex, and a wide variety of environmental pollutants, not only the existence of a certain kind of endocrine disruptors alone, this article also studied the combined effects of NP and BPA. In this study, we used NP, BPA and NP BPA exposure on zebrafish, the adult male zebrafish (Danio rerio) were exposed to different concentrations of NP (0,125,250,500 μg · L-1), BPA ( 0,500,1000,2000,400 μg · L-1) and NP62.5μg · LL BPA (0,500,1000,2000 μg · L-1) 21d, using conventional histological methods of test fish testis structure changes, by fluorescence quantitative PCR (QRT-PCR) was used to detect testicular hormone test fish synthase (CYP17, CYP11B and CYP19A) as well as estrogen, androgen receptors (ERα, AR) and follicle-stimulating hormone receptor (FSHR) gene expression, while also tested liver vitellogenin (VTG) mRNA and ERα expression. The results showed: NP and BPA exposed zebrafish testis structure has changed with the increasing concentration of seminiferous tubules in reduced semen volume, sperm agglutination mature, non-cellular region increased; BPA concentration 1000μg · L-1 when there is a egg, NP and BPA has the highest concentration group testis tissue degradation. With increasing concentration of NP and BPA induced liver VTG and ERa mRNA expression, there has been a typical estrogenic effects. While promoting testis CYP19A mRNA expression, so can be used as fish testis in addition to environmental estrogens VTG biomarker outside, CYP19A and ERa gene expression could be used as environmental estrogens affect early warning. NP and BPA on CYP17 mRNA expression was significantly negatively correlated with reduced dose-response relationship, but when the two substances combined exposure, they promoted the CYP17 mRNA expression. NP inhibited CYP11B mRNA expression, BPA and NP BPA has promoted the expression of CYP11B. Seen in this light the mechanism of action of NP and BPA are not identical. NP and BPA on testicular AR mRNA expression was not significantly affected. BPA4000μg · L-1 时 obvious toxic effects, compared with the low concentration of sex hormones synthase expression in a downward trend. BPA and NP BPA exposure group combined have raised FSHR mRNA expression. (NP62.5 BPA500) μg · L-1 is displayed antagonism, (NP62.5 BPA1000) μg · L-1 displays synergistic effect, and essentially the most significant difference between groups. Conclusions: (1) NP and BPA had an impact on the testis, with increasing concentrations of seminiferous tubules in reduced semen volume, sperm agglutination mature, non-cell area increases, there egg. NP and BPA induced the expression of VTG and ERαmRNA estrogenic effects. (2) NP and BPA by inhibiting expression of CYP17, may inhibit testosterone (T) synthesis, by inducing the expression of CYP19A, the activation of endogenous estrogenic activity, promotes the synthesis of endogenous estrogen. (3) NP lowered CYP11B expression, BPA on the expression of CYP11B not much affected, and they did not affect the AR. Description NP inhibits androgen synthesis, but did not interfere with the role of androgen. BPA on androgen synthesis did not have an impact. (4) NP and BPA mechanism of action, are not identical, but they have destroyed the original hormone balance. (5) NP combined effects of BPA and there are both synergistic and antagonistic effects, NP disrupt the mechanism of action of BPA, the joint mechanism complicated.
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