The teleost sperm membrane progestogen receptor: Interactions with xenoestrogens

Although a wide variety of xenobiotic organic compounds have been shown to disrupt endocrine function by binding to nuclear steroid receptors, it is not known whether they can cause endocrine disruption by binding to steroid membrane receptors. The ability of four nonsteroidal estrogenic compounds to bind to the 17,20β,21-trihydroxy-4-pregnen-3-one (20β-S) receptor on Atlantic croaker (Micropogonias undulatus) sperm membranes was investigated in the present study. All four estrogenic compounds (Kepone, o,p′-DDE,2′,4′,6′-PCB-4-OH and zearalenone) displaced [3H]-20β-S from its receptor over a range of concentrations (100 nM–10 μM). These results suggest that steroid membrane receptors may be sensitive to interference by endocrine disrupting chemicals. The demonstration that Kepone can exert direct effects on croaker sperm resulting in a decrease in sperm motility in an in vitro bioassay system provides preliminary evidence in support of this hypothesis.