Interference by atrazine and bisphenol-A with progestin binding to the ovarian progestin membrane receptor and induction of oocyte maturation in Atlantic

Recent studies have shown that several environmental chemicals which disrupt classical genomic steroid actions can also interfere with nongenomic steroid actions initiated at the cell surface. The effects of bisphenol-A and atrazine on the nongenomic actions of a progestin, 17,20β,21-trihydroxy-4-pregnen-3-one (20β-S), on oocyte maturation (OM) were investigated an in vitro Atlantic croaker (Micropogonias undulatus) oocyte bioassay. Treatment of croaker follicle-enclosed oocytes with either bisphenol-A or atrazine blocked OM in response to 20β-S in a concentration-dependent manner at 10–25 μM (2.2–5.7 ppm) and higher concentrations. These compounds were also effective competitors at concentrations of 10−6–10−5 M of [3H]-20β-S binding to the ovarian progestin membrane receptor that mediates the OM response to 20β-S. The results suggest that diverse classes of environmental chemicals can disrupt nongenomic progestin actions via receptor-mediated mechanisms.