Persistence of infertility in GnRH immunized male rats treated with subdermal implants of dihydrotestosterone (DHT).

Male hormonal contraception has been limited to date because two fundamental requirements have not been concurrently satisfied, these are, consistent and dependable azoospermia and infertility coupled with maintenance of libido. The objective of this study was to determine the extent to which implants of potent androgen (DHT) will restore androgenization and spermatogenesis in hypogonadotropic infertile male rats. Twenty-five sexually mature male rats of proven fertility were actively immunized against gonadotropin releasing hormone (GnRH) to induce azoospermia. After azoospermia was achieved, GnRH immunized rats received subdermal DHT-filled Silastic implants of 2, 4, 6, or 8 cm, or empty implants (n=5/group). Five untreated control rats received empty capsules. Eight weeks later, fertility was evaluated, sperm number was obtained from the testis, and weights of androgen-dependent organs were measured. The results indicate that immunoneutralization of GnRH induced complete azoospermia, and subsequent treatment with DHT implants of 2 or 4 cm for 8 wk restored accessory organ weights, but did not restore spermatogenesis or fertility. In addition, DHT implants of 6 to 8 cm partially restored spermatogenesis, but not fertility. We conclude that low-dose DHT supplementation of GnRH-immunized rats may be a suitable alternate therapy able to maintain androgenization in the face of persistent azoospermia in the rat. This may be an effective model for development of a male contraceptive.