Maintenance of spermiogenesis by exogenous testosterone in rats treated with a GnRH antagonist: relationship with androgen-binding protein status.
The relationship of the testicular distribution and [3H]dihydrotestosterone-binding capacity of androgen-binding protein (ABP) to the completion of spermiogenesis was examined in mature rats given daily injections of 25 or 250 micrograms kg-1 body weight of GnRH antagonist (GnRH-A; Ac-D(2), Nal1, 4Cl-D, Phe2, D-Trp3, D-Arg6, D-Ala10) for two weeks with or without subcutaneous implantation of 10 cm testosterone capsules. GnRH-A administration resulted in a dose-dependent suppression of serum FSH, which was partially prevented in the 250 micrograms GnRH-A kg-1 group by exogenous testosterone. The total testicular testosterone content and concentration of testosterone in seminiferous tubular fluid were equally suppressed in both groups of rats treated with GnRH-A and receiving the testosterone supplement. ABP concentrations in interstitial and seminiferous tubular fluid were normal in rats given the 25 micrograms GnRH-A kg-1 dose, and were increased (P < 0.05) by concomitant testosterone treatment. In contrast, ABP concentrations in interstitial and seminiferous tubular fluid were increased in rats given the 250 micrograms GnRH-A kg-1 dose. This effect was attenuated when exogenous testosterone was given. Although binding of [3H]dihydrotestosterone by ABP in seminiferous tubular fluid was not affected by GnRH-A treatment, with or without exogenous testosterone, it was reduced in interstitial fluid by GnRH-A in a dose-dependent manner, and partially restored by testosterone administration. While complete spermatogenesis was maintained in rats given 25 micrograms GnRH-A kg-1, the number of step 7 and step 19 spermatids were both reduced by 35%, and were not affected by testosterone implants.(ABSTRACT TRUNCATED AT 250 WORDS)
Pogach
L
L
Department of Medicine, Department of Veterans Affairs Medical Center, East Orange, NJ 07018.
Giglio
W
W
Nathan
E
E
Huang
H F
HF
D000727:Androgen-Binding Protein / Q000378:metabolism*; D000818:Animals; D003864:Depression, Chemical; D013196:Dihydrotestosterone / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005640:Follicle Stimulating Hormone / Q000097:blood; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives* / Q000494:pharmacology; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D009929:Organ Size / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D012661:Semen / Q000378:metabolism; D013087:Spermatids / Q000166:cytology; D013091:Spermatogenesis / Q000187:drug effects*; D013737:Testis / Q000166:cytology; D013739:Testosterone / Q000494:pharmacology*; D017329:Triptorelin Pamoate / Q000031:analogs & derivatives*
D000727:Androgen-Binding Protein; D017329:Triptorelin Pamoate; D013196:Dihydrotestosterone; D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone; C019176:Tryptal; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone