Immunoneutralization of gonadotropin-releasing hormone and subsequent treatment with testosterone Silastic implants in rats: an approach toward developing a male contraceptive.
OBJECTIVE
To determine the extent to which increasing doses of exogenous testosterone (T) administered via Silastic implants can restore spermatogenesis and fertility to rats made azoospermic by active immunization against gonadotropin-releasing hormone (GnRH).


METHODS
Male rats were made azoospermic by active immunization against GnRH. Increasing doses of exogenously administered T (via Silastic implants) were administered for 8 weeks, and testicular sperm concentration and ability to impregnate female rats were evaluated.


METHODS
Reproductive Endocrinology Laboratory, Department of Obstetrics and Gynecology, University of Colorado Health Sciences Center, Denver, Colorado.


METHODS
Sexually mature male Sprague Dawley rats (SASCO, Omaha, NE).


RESULTS
Suppression of gonadotropins and azoospermia was achieved by actively immunizing rats against GnRH. Testosterone was capable of restoring quantitatively complete spermatogenesis and fertility in GnRH-immunized azoospermic rats. This relationship was dose-dependent, as evidenced by the partial restoration of spermatogenesis and fertility observed in animals replaced with smaller T Silastic implants.


CONCLUSIONS
Gonadotropin-releasing hormone immunization and T-filled Silastic implants may provide a model to study isolated gonadotropin deficiency and for the development of a reversible male contraceptive.
Awoniyi
C A
CA
Department of Obstetrics and Gynecology, University of Colorado Health Sciences Center, Denver 80262.
Kim
W K
WK
Hurst
B S
BS
Schlaff
W D
WD
D000818:Animals; D003269:Contraception, Immunologic; D004343:Drug Implants; D005298:Fertility / Q000187:drug effects; D007987:Gonadotropin-Releasing Hormone / Q000276:immunology*; D007114:Immunization; D008297:Male; D009845:Oligospermia / Q000276:immunology; D051381:Rats; D011919:Rats, Inbred Strains; D013091:Spermatogenesis / Q000187:drug effects; D013739:Testosterone / Q000008:administration & dosage / Q000494:pharmacology*
D004343:Drug Implants; D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone