Reversible effects of long-term treatment with D-Trp6-LH-RH-microcapsules on pituitary-gonadal axis, spermatogenesis and prostate morphology in adolescent and adult dogs.
The effect of long term treatment with D-Trp6-LH-RH in microcapsules (GnRH-A) on pituitary gonadal axis was studied in a adolescent and adult Fox-terrier dogs. They received intramuscularly 50 micrograms/GnRH-A/kg, on day 1 and 21 and every 4 weeks thereafter. Three adult dogs received 4 injections. cLH, cFSH and T levels were undetectable on day 7. Detectable then normal levels occurred 60 and 90 days respectively after the last injection on day 77. Testis thickness was respectively 22.1 +/- 0.8 mm and 16.3 +/- 0.8 mm on days 0 and 77; initial values were observed 90 days later. Spermatozoa disappeared from the ejaculate on day 21 in 2 dogs; reappearance and complete recovery were observed on days 161-175 and 252 respectively. Histological findings showed on day 91 atrophic lesions of testis and prostate and spermatogonia were present in all seminiferous tubules. After recovery a normal histological appearance was noticed. Three adolescent 29 weeks old dogs received 14 injections, the last one on day 357. cLH, cFSH and T levels were undetectable only from day 105. Testis thickness were respectively 15.8 +/- 0.7 mm, 18.1 +/- 0.7 mm, 12.5 +/- 0.3 mm and 21.4 +/- 0.7 mm on day 0, 21, 357 and 490. Initially, no spermatozoa were present in the ejaculates, they appeared in 2 dogs after 2 months for 20 to 40 days then disappeared until day 449. Normal semen characteristics were observed in all three dogs on day 581. Histological findings on day 371 were comparable to those observed in the adult dogs. This study demonstrates that longterm treatment with D-Trp6-LH-RH in microcapsules leads to a reversible inhibition of spermatogenesis in dogs. The delayed response in adolescent dogs might be due to a transient resistance to therapy related to.
Cavitte
J C
JC
Ecole Nationale Vétérinaire d'Alfort, Maisons-Alfort, France.
Lahlou
N
N
Mialot
J P
JP
Mondain-Monval
M
M
Mialot
M
M
Nahoul
K
K
Morel
C
C
Roger
M
M
Schally
A V
AV
D000818:Animals; D002214:Capsules; D004285:Dogs; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D008297:Male; D010902:Pituitary Gland / Q000187:drug effects* / Q000502:physiology; D011467:Prostate / Q000187:drug effects* / Q000473:pathology; D012661:Semen / Q000032:analysis; D013091:Spermatogenesis / Q000187:drug effects*; D013737:Testis / Q000187:drug effects* / Q000502:physiology; D013997:Time Factors; D017329:Triptorelin Pamoate
D002214:Capsules; D017329:Triptorelin Pamoate; D007987:Gonadotropin-Releasing Hormone