[Effects of (+/-) and (+) 15-methyl PGF2 alpha methyl ester on early pregnancy]

Treatment with 15-methyl PGF2 alpha methyl ester (PG05) resulted in termination of pregnancy and peristatic effects in mice. (+) PG05 is the active stereoisomer of racemic PG05. The therapeutic index of (+) PG05 was found to be closely similar to that of (+/-) PG05. Pregnancy of ovariectomized rats given progesterone and estrone was maintained normally. PG05 was shown to have no effect on the gestation of ovariectomized rats receiving progesterone and estrone injection. PG05 at a concentration of 20 micrograms/ml reduced cAMP secretion of rat luteal cells in response to hCG in vitro. PG05 at concentration of 10 and 20 micrograms/ml also exerted an inhibitory effect on 8 Br-cAMP-stimulated progesterone production. These results suggest that in luteal cells PG05 inhibits steroidogenesis at the steps of gonadotropin-stimulated cAMP formation and cAMP-induced progesterone production.