STUDIES ON THE HISTOLOGY AND PHYSIOLOGY OF THE PITUITARY OF RATS TREATED WITH PROGESTERONE11

Abstract

Injs. of progesterone at daily dose levels of 1/2-3 mg. in castrated adult [male] and [female] rats did not prevent or correct histological castration changes in the ant. pituitary. Distinct hypertrophy of the pituitary occurred in castrated [male][male] treated with progesterone; in spayed [female][female] hypophyseal wt. changes were irregular. The effect of progesterone on the pituitary gland was studied in parabiotic rats by its ability to influence gonadotrophic activity of a castrated parabiont as judged by the testicular or ovarian response in a hypophysectomized twin. Progesterone was a weak gonadotrophic depressant, the smallest effective dose being 3 mg. daily. In instances where progesterone suppressed gonadotrophic activity of the pituitary, it did not exert a selective inhibitory action, for it caused inhibition of the gonadotrophins responsible for stimulation of tubular and interstitial cells of the testis.