Several Environmental Pollutants Have Binding Affinities for Both Androgen Receptor and Estrogen Receptor α

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We determined the binding affinities of some chemicals suspected of having endocrine-disrupting effects for androgen and/or estrogen receptors (ADR and ERα) by a non-radioisotope (RI) receptor binding assay. Tributyltin had the highest binding affinity for ADR with an IC₅₀ of 7.6 × 10^-6 M, but no affinity for ERα. Bisphenol A and 4-nonylphenol strongly bound to both ADR (IC₅₀ values of 7.9 × 10^-6 and 1.3 × 10^-5 M, respectively) and ERα (IC₅₀ values of 7.8 × 10^-6 and 7.2 × 10^-7 M, respectively). Octachlorostyrene had affinity for both receptors (IC₅₀ for ADR, 2.7 × 10^-5 M; and for ERα, 7.0 × 10^-5 M). Although 4-octylphenol had a low affinity for ADR, it had a high affinity for ERα (IC₅₀ of 9.8 × 10^-6 M). Di-n-butyl phthalate, dicyclohexyl phthalate, and di(2-ethylhexyl)phthalate had low affinities for both ADR and ERα. The affinity of benzophenone was low for both receptors and n-butylbenzene had no affinity for either. Styrene trimers such as 1a-phenyl-4a-(1'-phenylethyl)tetralin (ST-2), 1a-phenyl-4e-(1'-phenylethyl)tetralin (ST-3), 1e-phenyl-4a-(1'-phenylethyl)tetralin (ST-4), and 1e-phenyl-4e-(1'-phenylethyl)tetralin (ST-5) had relatively high affinities, with IC₅₀ values of 1.2-3.1 × 10^-5 M. Styrene dimers showed lower affinities for ADR than the trimers. Some styrene oligomers have been previously reported to have binding affinities for ERα. These findings suggest that some chemicals possess binding affinities for ADR and ERα. It is necessary to examine the effects of substances on various hormone receptors to elucidate their endocrine-disrupting activities.