Androgen and antiandrogen receptor binding.

Recent studies have demonstrated that androgenic stimulation of early and late responding genes depends on the nuclear uptake of the receptor-steroid complex. The longer the complex is retained in the nucleus, the shorter the lag period and the greater the magnitude of the response. Most antiandrogens or their metabolites bind to the cytosolic androgen receptor, but the relative receptor binding affinities do not strictly relate to their biological activities, since the former assay does not differentiate antagonists from weak agonists. Alternatively, androgen antagonists are believed to abrogate the action of androgenic steroids by interfering with the receptor function. However, the exact mechanisms by which antiandrogens bring about their actions remain to be established.