Inhibition of Pregnant Mare’s Serum-Induced Ovulation in the Immature Rat

Abstract

Superovulation was obtained in immature female rats following a single injection of pregnant mare’s serum gonadotropin (PMS). The induced ovulation was blocked by hypophysectomy and various pharmacological agents. A differential drug action was observed with atropine sulfate, chlorpromazine (CPZ), Nembutal and N-(9- fluorenyl) -N-ethyl-β-chloroethylamine hydrochloride (SKF-501) in the time of the blockade of the ovulatory response. The action of atropine was shown to precede that of SKF- 501, Nembutal, hypophysectomy and CPZ. CPZ suppressed LH release at a later period than any of the other agents used. The time of PMS injection, under controlled lighting conditions of 13 hr light and 11 hr dark, had no effect on the ovulatory or blocking response in the 24-day-old rat. PMS-induced ovulation in the immature rat appears to involve a neuroendocrine mechanism which can be inhibited by the action of certain drugs on the central nervous system. (Endocrinology74: 309, 1964)