OVARIAN INFLUENCE ON THE RESPONSE OF THE ANTERIOR PITUITARY TO ESTROGENS

Abstract

When estrogen is given to the immature [female] rat there is an increase in ovarian and pituitary wt. in 72-120 hrs. The pituitary decreases in gonadotrophic hormone content in 72-96 hrs. The loss of pituitary potency precedes the increase in ovarian wt., indicating that effective quantities of gonado-trophin are released into the blood stream. Small doses of estrogen, 1-2 [gamma], are sufficient to produce these effects. If the rats are spayed the day before the initiation of estrogen treatment, the pituitary does not decrease in potency in 96 hrs. even though the dose of estrogen is increased up to 200 [gamma]. A prepn. similar to Westerfeld''s lactone was the only estrogen which failed to produce the effects described above in the intact infantile rat. Testosterone in doses up to 0.5 mg. did not affect ovarian wt. or reduce the gonadotrophic potency of the pituitary. Progesterone or testosterone in doses of 1.0 mg. given simultaneously with the estrogens nullified their effect on ovarian wt. and pituitary potency. The ovary accelerates or augments the estrogen stimulation of the pituitary of the infantile [female] rat. Possible mechanisms whereby the ovary may participate in this action are discussed.