TY - JOUR
T1 - Effects of a gonadotropin-releasing hormone analog on rabbit ovarian function
AU - Zanagnolo, Vanna
AU - Dharmarajan, Arunasalam M.
AU - Hesla, John
AU - Wallach, Edward E.
PY - 1996
Y1 - 1996
N2 - This study was undertaken to elucidate the effects of a GnRH analog (GnRH-a) on rabbit ovulation, oocyte maturation, and steroidogenesis, and to verify whether treatment with a GnRH-a interferes with ovarian response to exogenous gonadotropin (hCG), both in vivo and in vitro. Three approaches were used. In the first, adult New Zealand White (NZW) rabbits were divided into two groups. Both received PMSG and hCG administered 72 h after PMSG. In the test group a GnRH-a, leuprolide acetate (LA; 20 μg/kg) was administered sc every 24 h. Treated rabbits showed a significant decrease in ovulatory efficiency (control = 88%; treated = 72%), and an increase in degeneration rate of preimplantation embryos (control = 30% vs. treated = 40%). For the second approach, in vitro perfusion experiments were designed to compare the direct effects of LA (10.000 ng/ml) and hCG (50 IU) on ovarian function and to verify whether the presence of a GnRH-a in the perfusate modifies the actions of hCG. LA reduced the ovulatory efficiency of hCG-treated ovaries perfused in vitro (hCG-treated =87%; hCG-treated LA-perfused = 70%), reduced the potential for preimplantation development (morula stage: hCG-treated = 53%; hCG-treated LA-perfused = 31%; LA-perfused = 12%), and increased the degeneration rate of early embryos (21%, 48%, and 56% respectively). In the third approach, the direct effect of LA (Group I: control, Group II:1.000 ng/ml, and Group III:10.000 ng/ml) on the in vitro maturation of denuded rabbit oocytes was evaluated. LA induced meiotic maturation, hut increased oocyte degeneration rate. The potential for preimplantation development was reduced (Morula stage: control = 16%, Group II = 8%, and Group III = 6%), and degeneration trite was increased (38%, 65%, 63% respectively). This study suggests that pharmacological doses of LA may exert a negative effect on oocyte function by direct action on the oocyte, indirectly via alteration of the intrafollicular environment and/or through interference with gonadotropin-induced biological effects within the ovary.
AB - This study was undertaken to elucidate the effects of a GnRH analog (GnRH-a) on rabbit ovulation, oocyte maturation, and steroidogenesis, and to verify whether treatment with a GnRH-a interferes with ovarian response to exogenous gonadotropin (hCG), both in vivo and in vitro. Three approaches were used. In the first, adult New Zealand White (NZW) rabbits were divided into two groups. Both received PMSG and hCG administered 72 h after PMSG. In the test group a GnRH-a, leuprolide acetate (LA; 20 μg/kg) was administered sc every 24 h. Treated rabbits showed a significant decrease in ovulatory efficiency (control = 88%; treated = 72%), and an increase in degeneration rate of preimplantation embryos (control = 30% vs. treated = 40%). For the second approach, in vitro perfusion experiments were designed to compare the direct effects of LA (10.000 ng/ml) and hCG (50 IU) on ovarian function and to verify whether the presence of a GnRH-a in the perfusate modifies the actions of hCG. LA reduced the ovulatory efficiency of hCG-treated ovaries perfused in vitro (hCG-treated =87%; hCG-treated LA-perfused = 70%), reduced the potential for preimplantation development (morula stage: hCG-treated = 53%; hCG-treated LA-perfused = 31%; LA-perfused = 12%), and increased the degeneration rate of early embryos (21%, 48%, and 56% respectively). In the third approach, the direct effect of LA (Group I: control, Group II:1.000 ng/ml, and Group III:10.000 ng/ml) on the in vitro maturation of denuded rabbit oocytes was evaluated. LA induced meiotic maturation, hut increased oocyte degeneration rate. The potential for preimplantation development was reduced (Morula stage: control = 16%, Group II = 8%, and Group III = 6%), and degeneration trite was increased (38%, 65%, 63% respectively). This study suggests that pharmacological doses of LA may exert a negative effect on oocyte function by direct action on the oocyte, indirectly via alteration of the intrafollicular environment and/or through interference with gonadotropin-induced biological effects within the ovary.
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U2 - 10.1210/endo.137.12.8940363
DO - 10.1210/endo.137.12.8940363
M3 - Article
C2 - 8940363
AN - SCOPUS:0030459398
SN - 0013-7227
VL - 137
SP - 5400
EP - 5406
JO - Endocrinology
JF - Endocrinology
IS - 12
ER -