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6305135 
Journal Article 
Abstract 
In vitro rat prostate androgen receptor competitive binding assay of propanil (CAS no. 709-98-8) 
Thomas, J; Macelrevey, CM; Godsey, J; Piccirillo, VJ 
2009 
Yes 
International Journal of Toxicology
ISSN: 1091-5818
EISSN: 1092-874X 
28 
1 
46-47 
English 
WOS:000267425000015 
Some xenobiotics are known to induce developmental and reproductive toxicological effects via endocrine disruption. The androgen receptor (AR) assay used in this study is one of the assays proposed by the US Environmental Protection Agency (EPA) Endocrine Disruptor Screening Program for evaluating compounds for their potential to cause endocrine disruption. The AR binding assay specifically investigates whether a test compound has the potential to be an endocrine system disruptor by measuring in vitro binding to the receptor responsible for key steps in the development of male sexual characteristics. Prostates from castrated rats were collected and processed, and preliminary saturation binding assays were performed to ensure AR binding activity and specificity in the cytosol. We demonstrated the response of the test system to known control compounds, including those with strong (testosterone), weak (hydroxyflutamide), and nominal (corticosterone) affinity, and evaluated propanil for the ability to bind to the AR. Propanil exhibited an IC50 (50% inhibition of reference ligand binding) of 59 mM and a relative binding affinity of 0.0035% for the AR when in competition with 1 nM of the synthetic radiolabeled androgenic ligand, [3H]-17a-methyltrienolone. On the basis that the competition experiment resulted in a calculable IC50, the Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM) guidelines (NIH Pub. No.03- 44503) recommend the classification of propanil as a weak binder of the AR. Despite weak binding to the androgen receptor, propanil appears unlikely to affect endocrine disruption via the AR pathway. 
Androgen receptor binding; Endocrine Disruptor Screening Program; Propanil