ACTION OF PROGESTERONE ON THE GONADOTROPIC ACTIVITY OF THE PITUITARY

Abstract

The inj. of 4 mg. of progesterone during 3 or 4 days into normal adult rats effectively prevented the induction of pseudopregnancy from cervical stimulation. One tenth to 1 mg. progesterone injected into immature rats together with follicle stimulating hormone for 4 to 10 days decreased the ovarian wt. response and inhibited luteinization. In hypophysectomized immature rats no inhibition was obtained. Progesterone suppressed the release of luteinizing hormone from the pituitary and this suppression was evidently responsible for the absence of estrus cycles during periods of luteal function. Some pituitary hormone other than luteinizing hormone was responsible for the continued function of formed corpora lutea.