Departments of Obstetrics and Gynecology and Biological Chemistry

Summary: A study of the ovary as a site of action of arginine vasotocin, a nonapeptide synthesized in the pineal gland of vertebrates, was conducted in the rat. Progesterone production stimulated by either human Chorionic Gonadotropin or 8Br-cyclic Adenosine 3 ',5 ' Monophosphate was s ign i f i cant ly reduced in rats pretreated with arginine vasotocin. The a f f in i ty and receptor number for human chorionic gonadotropin were uneffected by pretreatment with arginine vasotocin. These results suggest that the antigonadotropic action attr ibuted to arginine vasotocin may be due to an inh ib i t ion of ovarian steroidogenesis at a point distal to cycl ic Adenosine 3 ',5 ' Monophosphate formation