Direct effect of gonadotropin-releasing hormone agonists on the rabbit ovarian follicle.
OBJECTIVE
To determine if gonadotropin-releasing hormone agonist (GnRH-a)-induced oocyte maturation and degeneration can be attributed to the direct actions on the follicle.


METHODS
Mature rabbit follicle culture.


METHODS
The mature follicles were cultured with human chorionic gonadotropin (hCG) (100 ng/mL), buserelin acetate (10(-9) to 10(-6) M), leuprolide acetate (10(-9) to 10(-6) M), or buserelin acetate (10(-7) M) with a GnRH antagonist (10(-8) to 10(-6) M) for 14 hours.


METHODS
The percentage of oocytes achieving germinal vesicle breakdown, the oocyte degeneration rate, prostaglandins (PG) production by mature follicles, and the frequency of fertilization and embryonic development.


RESULTS
Gonadotropin-releasing hormone agonist induced the meiotic maturation of follicle-enclosed oocytes in a dose-dependent manner while concomitantly increasing oocyte degeneration. The simultaneous addition of GnRH antagonist inhibited significantly GnRH-a-induced oocyte maturation and PG production by the mature follicles. Furthermore, a GnRH antagonist reversed the oocyte degeneration rate that had been increased by GnRH-a. The rates of normal fertilization and early embryonic development were significantly reduced in the oocytes matured by GnRH-a as compared with those matured by hCG.


CONCLUSIONS
Gonadotropin-releasing hormone agonist acts directly on mature rabbit follicles to trigger the oocytes to undergo meiotic maturation, but oocytes matured in vitro by GnRH-a are not necessarily cytoplasmically mature.
Yoshimura
Y
Y
Department of Obstetrics and Gynecology, Kyorin University School of Medicine, Tokyo, Japan.
Nakamura
Y
Y
Ando
M
M
Shiokawa
S
S
Koyama
N
N
Nanno
T
T
D000818:Animals; D002064:Buserelin / Q000494:pharmacology*; D016922:Cellular Senescence / Q000187:drug effects; D006063:Chorionic Gonadotropin / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005307:Fertilization in Vitro; D007987:Gonadotropin-Releasing Hormone / Q000037:antagonists & inhibitors / Q000502:physiology*; D016729:Leuprolide / Q000494:pharmacology*; D008540:Meiosis / Q000187:drug effects; D009865:Oocytes / Q000187:drug effects; D006080:Ovarian Follicle / Q000187:drug effects* / Q000378:metabolism; D011453:Prostaglandins / Q000378:metabolism; D011817:Rabbits
D006063:Chorionic Gonadotropin; D011453:Prostaglandins; D007987:Gonadotropin-Releasing Hormone; D016729:Leuprolide; D002064:Buserelin