BLOCKADE OF OVULATION IN THE RAT BY A PROSTAGLANDIN ANTAGONIST (N-0164)

Abstract

Department of Pharmacology, Chelsea College, Manresa Road, London, SW3 6LX, and *Department of Physiology, St George's Hospital Medical School, Tooting, London, SW17 OQT (Received 12 May 1977) There is evidence accumulating to suggest that prostaglandins (PG) have a hypothalamic action in mediating the preovulatory surge of luteinizing hormone from the pituitary gland. Intraventricular injection of inhibitors of PG synthesis has been shown to block ovulation (Behrman, Orczyk & Greep, 1972; Orczyk & Behrman, 1972) and this effect can be overcome by subsequent administration of PG or luteinizing hormone releasing hormone. Similarly, PGE2, administered intraventricularly, can overcome the ovulatory blockade induced by the α-adrenoceptor antagonist phentolamine (Linton, Perkins & Whitehead, 1977). In this study, we have investigated the action of the prostaglandin antagonist N-0164 (Eakins, Rajadhyaksha & Schroer, 1976) on ovulation in the rat. Female Wistar rats weighing between 230 and 280 g were maintained under a controlled lighting schedule (12