Journal of Clinical Endocrinology & Metabolism, Vol 80, 1541-1547, Copyright © 1995 by Endocrine Society

ARTICLES

Midcycle levels of sex steroids are sufficient to recreate the follicle- stimulating hormone but not the luteinizing hormone midcycle surge: evidence for the contribution of other ovarian factors to the surge in normal women

AE Taylor, H Whitney, JE Hall, K Martin and WF Crowley Jr
Reproductive Endocrine Unit, Massachusetts General Hospital, Boston 02114, USA.

The midcycle surge of LH and FSH is critical for final oocyte maturation and ovulation. In normal women, this gonadotropin surge follows a gradual increase in estradiol levels (E) and is concomitant with a small increase in progesterone (P) levels. However, whether sex steroids alone are sufficient to induce the complex neuroendocrine interactions underlying this switch from negative to positive feedback is unknown. In this study, physiological midcycle levels of E, with and without periovulatory levels of P (E+P and E, respectively) were infused into 18 normally cycling women in their early to midfollicular phases. The resulting sex-steroid-induced gonadotropin responses were then compared with 118 spontaneous midcycle surges in 81 normal women. The sex steroid levels achieved by the infusions were within the normal ranges for the spontaneous midcycle surge. However, neither women who received E alone nor those who received E+P had LH responses that achieved those of spontaneous LH surges in the normal menstrual cycle (NMC) [82.7 +/- 16.23 IU/L E (mean +/- SEM), 69.7 +/- 12.01 IU/L E+P vs. 121.7 +/- 6.23 IU/L NMC, P < 0.05 E and P < 0.005 E+P vs. NMC]. In contrast, peak FSH levels evoked by E and P matched the spontaneous FSH peaks (19.0 +/- 2.1 IU/L E, 24.5 +/- 4.0 IU/L E+P vs. 23.3 +/- 0.9 IU/L NMC, P = 0.07 E and P = 0.71 E+P vs. NMC). In conclusion, sex steroids alone do not seem to be sufficient to stimulate the normal midcycle LH surge. We hypothesize that other ovarian factors, which are missing in the midfollicular phase, are required for the generation of the normal midcycle surge of LH.

This article has been cited by other articles:

				J. D. Veldhuis, D. M. Keenan, J. N. Bailey, A. Adeniji, J. M. Miles, R. Paulo, M. Cosma, and C. Soares-Welch Estradiol Supplementation in Postmenopausal Women Attenuates Suppression of Pulsatile Growth Hormone Secretion by Recombinant Human Insulin-like Growth Factor Type I J. Clin. Endocrinol. Metab., November 1, 2008; 93(11): 4471 - 4478. [Abstract] [Full Text] [PDF]

				W. E. Ottowitz, D. D. Dougherty, A. J. Fischman, and J. E. Hall [18F]2-Fluoro-2-Deoxy-D-Glucose Positron Emission Tomography Demonstration of Estrogen Negative and Positive Feedback on Luteinizing Hormone Secretion in Women J. Clin. Endocrinol. Metab., August 1, 2008; 93(8): 3208 - 3214. [Abstract] [Full Text] [PDF]

				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]

				T. P. Sharma, C. Herkimer, C. West, W. Ye, R. Birch, J. E. Robinson, D. L. Foster, and V. Padmanabhan Fetal Programming: Prenatal Androgen Disrupts Positive Feedback Actions of Estradiol but Does Not Affect Timing of Puberty in Female Sheep Biol Reprod, April 1, 2002; 66(4): 924 - 933. [Abstract] [Full Text] [PDF]

				E. Xiao, L. Xia-Zhang, D. Shanen, and M. Ferin Tonic Support of Luteinizing Hormone Secretion by Adrenal Progesterone in the Ovariectomized Monkey Replaced with Midfollicular Phase Levels of Estradiol J. Clin. Endocrinol. Metab., July 1, 1997; 82(7): 2233 - 2238. [Abstract] [Full Text] [PDF]