Metoclopramide potentiates the hypophyseal reactions to oestradiol.

Male rats to which oestradiol benzoate was administered intramuscularly twice a week for three weeks in 1 mg doses as an aqueous microcrystal suspension showed an increase in adenohypophyseal weight, in the number of lactotropic cells in the adenohypophysis (demonstrated by immunohistochemical detection of prolactin) and in polyphenol oxidase (ceruloplasmin) activity in the blood and hypothalamus. The simultaneous administration of metoclopramide (methoxychloroprocainamide) in doses of 10 mg/rat per day in food potentiated the adenohypophyseal reaction to oestradiol (weight and the number of lactotropic cells), but potentiated the polyphenol oxidase reaction only little or not at all. Metoclopramide thus has an anti-dopaminergic effect similar to that of perphenazine and other inhibitors of dopaminergic neurones.