A comparative study on involvement of tPA activity in ovulation induced by hCG and GnRH agonist in hypophysectomized rats.
A GnRH agonist (5-50 micrograms) is capable of inducing ovulation in PMSG-primed hypophysectomized immature rats, as is the case in hCG-induced ovulation, but 2-4 h earlier than hCG. GnRH-induced ovulation is effectively blocked by the concomitant administration of the GnRH-antagonist which failed to interfere with hCG-induced ovulation, indicating that GnRH and its agonists do not share a receptor with LH/hCG. Like hCG, GnRH is also capable of inducing tissue type (tPA), but not urokinase type (uPA) PA. The plasminogen activator activity in ovarian homogenates and the granulosa and theca-interstitial cells increase in a time-dependent manner, reaching maximum levels just prior to ovulation. Similar to hCG, GnRH also increases tPA activity in cumulus-oocyte complexes in a time-dependent fashion.
Liu
Y X
YX
Laboratory of Reproductive Biology, Academia Sinica, Beijing, PRC.
Feng
Q
Q
Stefan
C
C
D000818:Animals; D006063:Chorionic Gonadotropin / Q000494:pharmacology*; D004967:Estrogens / Q000097:blood; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000502:physiology*; D006107:Granulosa Cells / Q000201:enzymology; D007016:Hypophysectomy; D010053:Ovary / Q000201:enzymology; D010060:Ovulation / Q000187:drug effects; D010062:Ovulation Induction; D011374:Progesterone / Q000097:blood; D051381:Rats; D011919:Rats, Inbred Strains; D010959:Tissue Plasminogen Activator / Q000378:metabolism; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism
D006063:Chorionic Gonadotropin; D004967:Estrogens; D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; D010959:Tissue Plasminogen Activator; D014568:Urokinase-Type Plasminogen Activator