Inhibitory Effect of Clomiphene Citrate on the Conversion of 13, 14-Dihydro-15-Keto-Prostaglandin F_2α to 13, 14-Dihydro-Prostaglandin F_2α in Rat Ovary

Abstract

The effects of clomiphene citrate (clomiphene) on the in vitro conversion of 13, 14-dihydro-15-keto-prostaglandin F_2α (15KD-PGF_2α) to 13, 14-dihydro-prostagland in F_2α (13, 14H₂2-PGF_2α) in the presence of rat ovarian homogenate, and the relationship between clomiphene and gonadotropin or estrogen in the conversion were investigated. Although clomiphene inhibited the increased conversion of 15KD-PGF_2α 13, 14H₂-PGF_2α by pregnant mare serum gonadotropin (PMS) in rat ovary, the drug did not inhibit the decreased conversion of 15KD-PGF_2α by estradiol. The 3-day administration of clomiphene reduced the conversion of 15KD-PGF_2α to13, 14H₂-PGF_2αdose-dependently. A single administration of clomiphene also decreased the conversion, and this decreasing effect was similar to that of estradiol. On the other hand, the repeated administration of clomiphene decreased the ovarian and uterine weights and also inhibited the increase of the uterine weight by PMS or estradiol. These results suggest that clomiphene affects the ovarian enzyme catalyzing the conversion of 15KD-PGF_2α to 13, 14H₂-PGF_2α.