The effect of reported prostaglandin synthetase inhibitors on estradiol-stimulated uterine prostaglandin biosynthesis in vivo in the ovariectomized rat.

Aspirin, indomethacin and naproxen have been shown to inhibit the release of prostaglandins E and F (PGE and PGF) from the estradiol-stimulated uterus of progesterone-pretreated ovariectomized rats. Under the present experimental conditions indomethacin (1 mg/rat) was found to be a potent inhibitor of PGF and E biosynthesis, but the duration of action was less than 24 hours, after which a rebound above control levles was observed.The compounds were without effect on estradiol-stimulated increases in uterine wet weight. delta'THC did not inhibit estradiol-stimulated PG biosynthesis but produced a significant rise (P less than 0.01) in PGE levels in uterine venous blood. A hypothesis is suggested to explain some of the pharmacological effects of delta'THC.