Prostaglandins in the menstrual cycle of women. A review

The changes of concentrations of prostaglandins (PG) are cyclic in the uterine tissues and related to steroid ovarian hormones. The role in normal menstruation is presumably related to a local haemodynamic effect. PGF2 alpha vasoconstricts the endometrial vessels during menstruation and contracts the smooth muscle of the myometrium. PGE2 vasodilates the vessels of the endometrium, and PGI2 relaxes smooth muscle, vasodilates the vessels of the myometrium and inhibits thrombocyte aggregation. The pathological conditions dysmenorrhea and menorrhagia relates to symptoms which seem to be exaggerations of normal activities, probably due to increased PG levels. Prostaglandin synthesis inhibitors (PGSI) in women have not been able to prevent ovulation, but animal experiments have shown that the bursting of the follicle demands prostaglandins. In vitro experiments with human tissue have shown that PG is necessary for the occurrence of dissociation of connective tissue around the apex. Luteolysis is due to PG in several species, but it has not been possible to find this direct effect of PG upon luteolysis in women. However, there are indications that the PG functions as a mediator for or is mediated by catecholamines and/or oxytocin.