Ovulation induced by a gonadotropin releasing hormone analog in hypophysectomized rats involves prostaglandins.

A potent analogue of gonadotropin releasing hormone [D-Ala6- Des-Gly10-NH2]-GnRH ethylamide (GnRHa) caused oocyte maturation and ovulation when injected in the afternoon of proestrus in immature PMSG-treated female rats, hypophysectomized on the morning of proestrus. This action of GnRHa was accompanied by a marked increase in ovarian PGE levels. Furthermore, the pretreatment of the animals with a prostaglandin synthetase inhibitor (indomethacin) completely inhibited this PGE increase and ovulation. These data suggest a role for prostaglandins in GnRHa induced ovulation.