Local ovarian effects of prostaglandins E₂ and F_2α on human chorionic gonadotropin-induced ovulation in the rabbit

Ovarian smooth muscle and autonomic nerves have been suggested as significant factors in the mechanism of ovulation. Experiments using inhibitors of prostaglandin (PG) synthesis have indicated that ovarian PG’s may also be involved in the ovulatory process. Previous studies have shown that PGF_2α enhances and PGE₂ inhibits ovarian contractility in the rabbit. The present study was conducted to determine the effects of PGE2 and PGF2α on human chorionic gonadotropin-induced ovulation in the rabbit. Three groups of 10 rabbits each were utilized: one group served as a control; one group received PGE_2α and a third group received PGF_2α Experimental solutions were administered via an aortic catheter into the ovarian circulation, beginning 7 hours alter induction of ovulation with human chorionic gonadotropin (HCG) and continuing over the next -1 hours. At 7, 11, 14, and 32 hours after HCG administration, follicles on the ovarian surface were counted and categorized into four stages of development. Administration of PGE₂ led to a delay in ovulation, while ovaries of PGF_2α-treated animals ovulated at the same rate as the controls. The relationship of these results to previous conclusions about prostaglandin effects on the ovarian neuromuscular complex is presented. The role оf prostaglandins as in termed in tes in the ovulatory process is discussed.