A prostacyclin analogue, iloprost, augments the ovulatory response of the LH-stimulated in vitro perfused rat ovary.

Ovaries from immature rats, primed with pregnant mare's serum gonadotropin (PMSG; 20 IU, on day 28), were perfused in vitro in a recirculating system for 21 h from the morning of day 30 of age. Stimulation with luteinizing hormone (LH; 0.1 micrograms/ml) in vitro at 0 h of perfusion resulted in 2.4 +/- 0.75 (mean +/- SEM) ovulations per treated ovary, whereas no ovulations occurred in the unstimulated group. When the addition of LH was supplemented hourly for 10 h with a stable prostacyclin analogue, Iloprost, at concentrations of 0.01 microM or 0.1 microM, the ovulation rate increased significantly (p less than 0.05) to 6.6 +/- 1.3 and 10.2 +/- 2.4 ovulations per treated ovary, respectively. Iloprost (0.1 microM) did not cause any follicular ruptures when added by itself at every hour up to 10 h. The addition of Iloprost did not affect the release of cyclic adenosine 3',5'-monophosphate (cAMP), progesterone or estradiol from unstimulated or LH-stimulated ovaries. All ovulated oocytes had resumed meiosis as judged from the absence of a germinal vesicle. These data indicate a positive modulatory role of prostacyclin in the LH-induced ovulatory process for the rat.