Involvement of prostaglandins in the female reproductive cycle.

Orczyk & Behrman (1972) reported experiments in rats that indicated that prostaglandins, acting centrally, may have a role in regulating lutropin secretion from the pituitary. They found that systemically administered indomethacin [I-(Cchlorobenzoyl)-5-methoxy-2-methylindol-3-ylacetic a id] blocked ovulation, and this blockade could be overcome by administering lutropin. Later it was found that the injection of prostaglandin-synthesis inhibitors (eicosa-5,8,11,14-tetraynoic acid or indomethacin) into the third ventricle of ovariectomized rats decreased plasma lutropin concentrations (Ojeda et al., 1975). Tsafriri et al. (1973) reported that the systemic injection of prostaglandin E2 increased plasma lutropin concentrations in Nembutal-blocked pro-oestrus rats. Spies & Norman (1973) similarly reported that prostaglandin El increased plasma lutropin concentrations in Nembutal-blocked rats after administration into the third ventricle. Harms et al. (1974) demonstrated that prostaglandin E, was more potent in releasing lutropin in ovariectomized rats when given into the third ventricle than when given intravenously. Furthermore, prostaglandin EL was more potent than prostaglandin El , with prostaglandins F,. and F1. being inactive. Prostaglandin EL did not cause