Affinity of the alligator estrogen receptor for serum pesticide contaminants.

Top predators, like the American alligator (Alligator mississippiensis) bioaccumulate and biomagnify persistent pollutants, such as organochlorine pesticides. In a recently published study, several pesticides and pesticide metabolites not previously reported in alligator eggs were identified in the serum of juvenile alligators. This study examines the affinity of these compounds for the alligator estrogen receptor (aER) purified from adult oviductal tissue. Of the 11 compounds studied, 9 showed an affinity for the receptor, causing greater than 50% displacement of estradiol-17 beta from the aER. The most effective compounds were heptachlor epoxide and heptachlor, with IC50 of 19.4 and 26.7 microM, respectively. Two compounds, aldrin and Mirex showed little affinity for the aER. These data suggest that additional compounds are capable of acting as aER agonists or antagonists, but future research is needed to confirm in vivo actions, if any.