Androgen binding sites in human temporal cortex.

We have characterized putative androgen receptor binding sites in five separate biopsy samples of human temporal cortex from epilepsy patients using an in vitro exchange assay with soluble fractions and [3H]5 alpha-dihydrotestosterone as radioligand. The results revealed highly specific, saturable binding with an apparent affinity constant (Kd) of approximately 2 nM with a moderate capacity (Bmax) of approximately 50 fmol/mg protein. In competition studies, we found that only testosterone and 5 alpha-dihydrotestosterone competed effectively (i.e. at low nanomolar concentrations) for [3H]5 alpha-dihydrotestosterone binding sites. These data indicate the presence of androgen receptors in human cortex that are pharmacologically very similar to that previously described in rodent and infrahuman primate CNS, and suggest the existence of a possible mechanism whereby circulating androgens might influence neuronal events in human cortex.