The mode of action of indomethacin, aspirin and melatonin on the blockage of the first ovulation in immature rat pretreated with PMSG.

The purpose of this paper was to evaluate the anti-ovulatory effects of indomethacin, aspirin and melatonin by examining the LH sensitive 13,14-dihydroprostaglandin F2 alpha forming capacity in rat ovary. When ovulation was blocked by aspirin or melatonin, the forming capacity was strongly suppressed, and these effects were reversed by hCG injection. However, the ovulation blockage by indomethacin did not accompany the inhibition of the forming capacity. These results show that aspirin and melatonin block the ovulation via the hypothalamus-pituitary level, and indomethacin acts directly on the ovary.