Induction of in vitro vitellogenin synthesis by bisphenol, nonylphenol and octylphenol in Chinese minnow (phoxinus oxycephalus) hepatocytes

Abstract

Bisphenol A (BPA), nonylphenol (NP), and 4‐tert‐octylphenol (OP) are known endocrine disrupting chemicals (EDCs) with estrogenic activity in fish. This study compared the effects of BPA, NP and OP on in vitro vitellogenin (VTG) synthesis in primary cultures of hepatocytes of the Chinese minnow Phoxinus oxycephalus. The VTG secreted into the culture medium was measured using enzyme‐linked immunosorbent assay (ELISA), which we developed in this study using an antibody prepared from homogenates of Chinese minnow egg. VTG synthesis was induced by estradiol‐17β (E2) and phenols (BPA, NP and OP) treatment. E2 at concentrations of 10‐6 M or higher increased VTG levels significantly (P<0.05). Exposure to 10‐5 M BPA or 10‐4 M NP and OP induced in vitro VTG synthesis (P<0.01). However, 10‐3 M BPA, NP or OP did not induce VTG synthesis. These results suggest that BPA has the highest estrogenic potential in Chinese minnow hepatocytes. Tamoxifen, an anti‐estrogen, drastically blocked the production of VTG by phenols (BPA, NP and OP) suggesting that phenols (BPA, NP and OP) may act via binding to estrogen receptor (ER) in Chinese minnow hepatocytes.