Antiandrogen implanted in brain stimulates male reproductive system.

Chronic intrahypothalanic implantation of cyproterone, an antiandrogen, in male rats resulted in specific stimulation of testes, seminal vesicles, and prostates. Implantation of cholesterol-filled or empty tubes in the median eminence in controls was ineffective. We conclude that decreases in the amount of testosterone reaching specific receptors in the median eminence or in nearby regions activate a mechanism that produces increased gonadotropin secretion.