The relationship between prostaglandins and histamine in the ovulatory process as determined with the in vitro perfused rabbit ovary.
The process of follicle rupture has been described as an inflammatory reaction in which prostaglandins (PGs) and/or histamine may be involved. With an in vitro perfused rabbit ovary preparation, experiments were carried out for determination of whether a relationship exists among PGs, histamine, and ovulation. PGF2 alpha alone was capable of inducing ovulation when added to the perfusion fluid at 1, 10, and 100 ng/ ml. Effectiveness in achieving ovulation varied directly with the dosage; however, the ovulatory efficiency of PGF2 alpha-treated ovaries was lower than that of ovaries exposed to human chorionic gonadotropin (hCG, 100 IU). PGF2 alpha-induced ovulation could not be blocked by the H2 receptor antagonist, cimetidine. The PG synthesis inhibitor, indomethacin, did not prevent histamine-induced ovulation. Ovulation induced by hCG was partially blocked by the administration of indomethacin; however, the concomitant administration of cimetidine was not associated with further reduction in ovulation. In all but one experimental group, the majority of ovulated ova did not progress beyond the intact germinal vesicle stage unless the ovaries had been exposed to hCG. On the basis of these experiments, PGs and histamine do not appear to be interdependent in their effects on the ovulatory process in vitro.