LRFD6a has a dose-related stimulatory or inhibitory effect on the ovary in normal luteal phase women.

A dose response curve for LRFD6a-a potent LRF agonist-was established in normal midluteal phase women. At low doses (3-10 micrograms) an acute stimulatory effect on gonadotropins and ovarian steroidogenesis of estradiol and progesterone was observed. Despite large increases in circulating gonadotropins following the highest dose (30 micrograms LRFD6a), no acute changes in plasma steroids were noted. A sharp drop in progesterone was present after 3 days, with significant shortening of the cycle in 3 of 4 subjects in the group. While the stimulatory effect may be due to gonadotropin release and local action, the luteolytic effect observed is suggested to be a consequence of the direct inhibitory effect of the analog on ovarian function.