Inhibition of the formation of 13,14-dihydroprostaglandin F2-alpha induced by chlorpromazine in rat ovary

Abstract

The present study was designed to investigate the effects of chlorpromazine (CPZ) on the formation of 13,14H 2-PGF 2α in rat ovary and the possibility that the “critical period” observed in the effect of CPZ for the blockade of ovulatin may be appreciated by measuring the formation of 13,14H 2-PGF 2α as a parametor. When CPZ (4.0 mg/kg) was given s.c. at 10.00 a.m. once a day for 3 days from the first day of diestrus to the expected day of proestrus followed by sacrifice after 24 hours of the final injection, a significant inhibtion was recognized in the formation of 13,14H 2-PGF 2α in ovary. The effects of a single injection of CPZ were also determined 24 hours after injection at 10:00 a.m. on the day of diestrus I , diestrus II or proestrus. The results showed that the drug treatment on the day of proestrus significantly decreased the formation of 13,14H 2-PGF 2α , but not on the day of diestrus I or II. When the formation of ovarian 13,14H 2-PGF 2α was inhibited by CPZ treatment, the blockade of ovulation was also confirmed. A single injection of CPZ at 05:00 and 07:00 after the “critical period” on the day of proestrus did not inhibit the 13,14H 2-PGF 2α formation in the rat ovary. It is concluded that the administration of CPZ before the “critical period” on the day of proestrus is effective in suppressing the ovarian 13,14H 2-PGF 2α formation as well as on the blockade of ovulation.