Induction of ovulation in immature female rats by a single injection of 4-hydroxyoestradiol-dibenzoate.

This study was designed to test the ability of 2- and 4-hydroxyoestrogens to induce ovulations and the formation of corpora lutea in immature female rats. To this end 25 day old animals received a single injection of different doses of either 4-hydroxyoestradiol-dibenzoate (10, 25, 50 micrograms) or 2-hydroxyoestradiol-dibenzoate (25, 250 micrograms) or oestradiol-benzoate (10, 25, 60 micrograms). On day 31 the ovaries were checked for corpora lutea. 4-Hydroxyoestradiol-dibenzoate and oestradiol-benzoate in doses of 50 or 25 micrograms significantly increased the number of animals with corpora lutea whereas animals treated with 10 micrograms of either steroid did not differ significantly fron the respective vehicle groups. 2-Hydroxyoestradiol-dibenzoate, even at the high dose of 250 micrograms did not show a significant effect. This is the first demonstration that a catecholoestrogen - 4-hydroxyoestradiol - can induce ovulation. As its potency in doing so is similar to that of oestradiol and as 4-hydroxyoestradiol can be formed in neuroendocrine tissues from primary oestrogens, we conclude that this catecholoestrogen might play a role in the regulation of ovulation.