Abstract
Effect of nonylphenol (NP) products from different companies on in vitro vitellogenin (VTG) synthesis was compared using tilapia (Oreochromis mossambicus) hepatocytes cultures. Addition of NP at a concentration of 10-3 M to the medium caused death of hepatocytes (NP-A and NP-B) and delay of monolayer formation (NP-C). No cell death was observed at a concentration of 10-4 M (NP-A, -B and -C) but cell adhesion was slower than control. These results suggest that high concentration of NP is toxic against tilapia hepatocytes. When effects of estradiol-17β (E2, 10-7 M) and NP (10-4 M) on in vitro VTG synthesis were examined, addition of E2 and NP-A and NP-B to the media resulted in elevation of VTG. NP-C did not induce VTG in the medium. Co-treatment of NP-B and tamoxifen, a non-steroidal anti-estrogen, reduced VTG synthesis. These results suggest that NP has estrogenic potential in primary cultures of tilapia hepatocytes and acts through binding to the estrogen receptor, and that there is a difference in the induction level of VTG among different NP products.
