PITUITARY RESPONSE TO METOCLOPRAMIDE IN THE RAT

Abstract

Department of Medicine, The University of Chicago, Chicago, Illinois 60637, U.S.A. (Received 14 February 1977) Metoclopramide is a potent stimulator of prolactin release in man (Delitala, Masala, Alagna & Devilla, 1975; Judd, Lazarus & Smythe, 1976; McCallum, Sowers, Hershman & Sturdevant, 1976); its possible effect on other anterior pituitary hormones is not known. We have carried out two experiments with male Sprague-Dawley rats, 130–150 g in weight; the results presented here demonstrate that metoclopramide specifically stimulates the release of prolactin. Groups of five rats were injected s.c. with 0·9% saline (5 ml/kg body wt) containing 0-10 mg metoclopramide/kg (supplied by A. H. Robins Co., Richmond, Virginia). Thirteen minutes later the rats were immobilized with ketamine (supplied by Bristol Laboratories, Syracuse, New York), 100 mg/kg, i.p.; ketamine does not affect the level of prolactin in the plasma of rats (Lawson & Gala, 1974). Blood was drawn by heart puncture within 2