Endocrinology, Vol 129, 1447-1451, Copyright © 1991 by Endocrine Society

ARTICLES

Control of gonadotropin secretion in the ovine fetus. IV. Male-specific entrainment of the hypothalamic control of luteinizing hormone secretion by testosterone in the female ovine fetus

I Matwijiw and C Faiman
Department of Medicine, University of Manitoba, Winnipeg, Canada.

The role of testosterone (T) in the sex-specific entrainment of hypothalamic LH regulation was studied in five castrate and four sham- castrate chronically catheterized female fetuses androgenized by the prior administration of T cypionate (200 mg, im, every 2 weeks) to pregnant ewes from 30-86 days gestation (term = 147 days). Eight female and three male castrate fetuses served as controls. After a 2-week washout period all fetuses were operated upon in utero between 106-116 days and were studied longitudinally over a 2- to 35-day period. LH pulsatility was determined from blood samples obtained every 15 min over a standard 3-h observation period and assayed for LH by RIA (NIH LH-S16 standard). LH pulse frequency in the castrate androgenized females (41 pulses in 19 observation periods; 1 pulse/1.4 h) was significantly higher than that in non-androgenized female controls (18 pulses in 28 observation periods; 1 pulse/4.7 h observation), but was similar to that in castrate males (23 pulses in 28 observation periods; 1 pulse/1.3 h). Furthermore, LH pulse frequency in the sham castrate androgenized females (26 pulses in 13 observation periods; 1 pulse/1.5 h) was comparable to that in castrate androgenized females as well as that in castrate males. The enhanced LH pulsatility in androgenized female fetuses strongly suggests that T exposure between 30-86 days results in male-specific entrainment of hypothalamic LH regulation. Moreover, the comparable enhancement of LH pulse frequency in both sham castrate and castrate androgenized female groups suggests that in the T- exposed fetus T withdrawal alone is sufficient to result in enhanced LH pulsatility. These findings strongly suggest that T of fetal testicular origin results in male-specific entrainment of hypothalamic function and may be an important feature of male neural organization in this species.

This article has been cited by other articles:

				M. Manikkam, R. C. Thompson, C. Herkimer, K. B. Welch, J. Flak, F. J. Karsch, and V. Padmanabhan Developmental Programming: Impact of Prenatal Testosterone Excess on Pre- and Postnatal Gonadotropin Regulation in Sheep Biol Reprod, April 1, 2008; 78(4): 648 - 660. [Abstract] [Full Text] [PDF]

				E. M. Foecking, M. Szabo, N. B. Schwartz, and J. E. Levine Neuroendocrine Consequences of Prenatal Androgen Exposure in the Female Rat: Absence of Luteinizing Hormone Surges, Suppression of Progesterone Receptor Gene Expression, and Acceleration of the Gonadotropin-Releasing Hormone Pulse Generator Biol Reprod, June 1, 2005; 72(6): 1475 - 1483. [Abstract] [Full Text] [PDF]