Testicular interstitial cells as targets for peripheral benzodiazepines.

We evaluated the 'in vitro' effect of a selective peripheral benzodiazepine (BZD) receptor agonist, Ro 5-4864, on basal and hCG-stimulated androgen production by testicular interstitial cell suspensions. Ro 5-4864 (10(-9)-10(-5) M) induced a significant increment of basal testosterone release into the medium. In addition, under conditions of hCG stimulation, Ro 5-4864 (10(-7) M) induced a potentiated response to the gonadotropin in a dose-dependent manner. The selective peripheral BZD antagonist PK 11195 fully prevented the stimulatory effect of Ro 5-4864. On the other hand, clonazepam, a central BZD agonist, failed to affect androgen production significantly, whereas diazepam (10(-5)-10(-4) M), which binds to both central and peripheral BZD receptors, was able to induce a significant increment of basal and hCG-stimulated testosterone production. These results suggest that under our experimental conditions Ro 5-4864 exerts an effect on testicular steroidogenesis, presumably through binding to the previously described peripheral-type BZD receptor.