Abstract:
In order to study the effects of nonylphenol (NP) on estrogen receptor（ER）and vitellogenin（Vtg）in hepatocytes of male amphibian, adult male frogs Rana chensinensisas were exposed to the solutions containing 10-5, 10-6, 10-7 mol/L NP and 10-8, 10-9 mol/L 17β-estradiol (E2, positive control) for 10, 20, 30d respectively. The expression of ER mRNA in the hepatocytes was examined by in situ hybridization，and the immunoreactivity of ER and Vtg protein were examined by immunohistochemistry. The results show that the strongly positive reaction of ER mRNA was found in hepatocytes of male frogs treated with NP and E2. Compared with the control group, the relative intensities in expression of ER and Vtg were increased significantly in NP and E2 treatment groups, and a similar increased tendency for ER and Vtg was found. It is presented that ER expression and Vtg synthesis are in NP and E2 dose-dependent manner. Whereas, it is not regular that the expression levels of ER and Vtg are elevated with NP and E2 prolonged treatment. These were suggested that NP caused the vitellogenesis in the hepatocytes of male frogs was mediated by inducing the ER up-regulated. Though NP can induce the ER up-regulated, but its estrogenic activity is much lower than that of E2.
