Journal of Clinical Endocrinology & Metabolism, Vol 41, 820-826, Copyright © 1975 by Endocrine Society

ARTICLES

The effects of estrogen and progesterone on the functional capacity of the gonadotrophs

BL Lasley, CF Wang and SS Yen

The functional capacity of the gonadotrophs under the influence of exogenous estrogen and progesterone was assessed by repeated stimulation with submaximal doses of LH-releasing factor (LRF) (10 mug at 2-h intervals) of subjects during the early follicular phase of the cycle and of hypogonadal women. The initial increment of peak serum LH and FSH concentrations after the first administration of LRF, was used to describe the pituitary sensitivity, and the integrated release during the 10 hours of LRF-stimulated pulses was utilized to approximate the pituitary gonadotropin reserve. During the early follicular phase, response to LRF stimulations was relatively stable with corresponding release of LH and FSH. An augmentation of sensitivity, as well as the reserve, for both LH and FSH was elicited by an incremental change in circulating estradiol levels, a change imposed by daily administration of estradiol benzoate for 4 days during the early follicular phase. Under the same conditions, the addition of progesterone (10 mg, im) at the end of the estradiol benzoate treatment induced a marked amplification of the estrogen-augmented pituitary gonadotropin sensitivity and reserve. The pituitary sensitivity, relatively higher than the reserve in hypogonadal subjects, was reversed by the administration of ethinyl estradiol (20-50 mug/day) for 7 days. These data indicate that the functional capacity of the gondotrophs is profoundly modulated by estrogen through relative changes in pituitary sensitivity and reserve, and that progesterone in low doses exhibited an amplifying effect on estrogen-primed gonadotrophs in both the pituitary sensitivity and the reserve.

This article has been cited by other articles:

				I. E. Messinis Ovarian feedback, mechanism of action and possible clinical implications Hum. Reprod. Update, September 1, 2006; 12(5): 557 - 571. [Abstract] [Full Text] [PDF]

				K. Dafopoulos, C.G. Kotsovassilis, S. Milingos, A. Kallitsaris, G. Galazios, E. Zintzaras, P. Sotiros, and I.E. Messinis Changes in pituitary sensitivity to GnRH in estrogen-treated post-menopausal women: evidence that gonadotrophin surge attenuating factor plays a physiological role Hum. Reprod., September 1, 2004; 19(9): 1985 - 1992. [Abstract] [Full Text] [PDF]

				J. Nicholls, B. L. Lasley, S. T. Nakajima, K. D. R. Setchell, and B. O. Schneeman Effects of Soy Consumption on Gonadotropin Secretion and Acute Pituitary Responses to Gonadotropin-Releasing Hormone in Women J. Nutr., April 1, 2002; 132(4): 708 - 714. [Abstract] [Full Text] [PDF]

				I. E. Messinis, S. Milingos, E. Alexandris, I. Mademtzis, G. Kollios, and K. Seferiadis Evidence of differential control of FSH and LH responses to GnRH by ovarian steroids in the luteal phase of the cycle Hum. Reprod., February 1, 2002; 17(2): 299 - 303. [Abstract] [Full Text] [PDF]