title: In vitro synergistic interaction of alligator and human estrogen receptors with combinations of environmental chemicals.
abstract: The effect of mixtures of environmental chemicals with hormonal activity has not been well studied. To investigate this phenomenon, the estrogen receptor (ER) from the American alligator (aER) or human (hER) was incubated with [3H]17beta-estradiol in the presence of selected environmental chemicals individually or in combination. The environmental chemicals included the insecticide chlordane, which has no estrogenic activity, and the pesticides dieldrin and toxaphene, which have very weak estrogenic activity. Chlordane, dieldrin, and toxaphene individually demonstrated no appreciable displacement of [3H]17beta-estradiol from aER and hER at the concentration tested. A combination of these chemicals inhibited the binding of [3H]17beta-estradiol by 20 to 40%. Alachlor, a chemical recently discovered to have weak estrogenic activity, also displaced [3H]17beta-estradiol more effectively in combination with dieldrin than alone. These results indicate that combinations of some environmental chemicals inhibit [3H]17beta-estradiol binding in a synergistic manner. This suggests that the ER may contain more than one site for binding environmental chemicals. The possibility that the ER binds multiple environmental chemicals adds another level of complexity to the interaction between the environment and the endocrine system.
authors.affiliation: Tulane-Xavier Center for Bioenvironmental Research, Department of Environmental Health Sciences, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana 70112, USA. sarnold@mailhost.tcs.tulane.edu
authors.forename: S F
authors.initials: SF
authors.lastname: Arnold
authors.forename: P M
authors.initials: PM
authors.lastname: Vonier
authors.forename: B M
authors.initials: BM
authors.lastname: Collins
authors.forename: D M
authors.initials: DM
authors.lastname: Klotz
authors.forename: L J
authors.initials: LJ
authors.lastname: Guillette
authors.forename: J A
authors.initials: JA
authors.lastname: McLachlan
mesh_terms: D000081:Acetamides / Q000008:administration & dosage / Q000633:toxicity; D000489:Alligators and Crocodiles; D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D002706:Chlordan / Q000008:administration & dosage / Q000633:toxicity; D004026:Dieldrin / Q000008:administration & dosage / Q000633:toxicity; D004357:Drug Synergism; D004782:Environmental Health; D004958:Estradiol / Q000378:metabolism; D004968:Estrogens, Non-Steroidal / Q000008:administration & dosage / Q000633:toxicity; D006540:Herbicides / Q000008:administration & dosage / Q000633:toxicity; D006801:Humans; D066298:In Vitro Techniques; D007306:Insecticides / Q000008:administration & dosage / Q000633:toxicity*; D011960:Receptors, Estrogen / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D014112:Toxaphene / Q000008:administration & dosage / Q000633:toxicity
chemical_list: D000081:Acetamides; D004968:Estrogens, Non-Steroidal; D006540:Herbicides; D007306:Insecticides; D011960:Receptors, Estrogen; D011994:Recombinant Proteins; D002706:Chlordan; C000188:alachlor; D004958:Estradiol; D014112:Toxaphene; D004026:Dieldrin