Estrogenicity of 4-nonylphenol and diethylstilbestrol on in vitro oocyte maturation of the dusky tripletooth goby, Tridentiger obscurus

Abstract

This study investigated the estrogenicity of 4-nonylphenol (NP) and diethylstilbestrol (DES) in vitro during oocyte maturation in the marine fish, Tridentiger obscurus, using steroid hormone assays and GVBD assay. Vitellogenic (0.53 mm diameter) and fully vitellogenic (0.75 mm diameter) oocytes were in vitro exposed to NP (0.045–453.82 nM) and DES (0.037–372.62 nM). In vitellogenic oocytes, 45.38 and 453.82 nM NP and 3.73–372.62 nM DES increased the estradiol-17β (E2)/testosterone (T) ratio. In fully vitellogenic oocytes, 0.45, 45.38 and 453.82 nM NP and 3.73 nM DES increased E2/T. In the GVBD assay, 0.45 and 4.54 nM NP and 0.037, 3.73 and 37.26 nM DES inhibited GVBD. These results suggest that NP and DES have estrogen-agonistic effects in oocyte maturation in T. obscurus. In addition, NP and DES have different sensitivity according to the oocyte developmental stage, and the estrogen-agonistic effects of DES were greater than were those of NP.