Biology of Reproduction, Vol 31, 856-862, Copyright © 1984 by Society for the Study of Reproduction

ARTICLES

Experimental induction of estradiol positive feedback in intact male monkeys: absence of inhibition by physiologic concentrations of testosterone

PK Westfahl, HL Stadelman, LE Horton and JA Resko

Estradiol benzoate (E2B) induces an increase in serum luteinizing hormone (LH) in gonadectomized macaques of both sexes and in intact females but not males. To determine the interaction of testosterone (T) with E2B, we treated 6 intact male cynomolgus macaques as follows: 1) with E2B alone; 2) E2B after pretreatment with estradiol-17 beta (E2) for 2 wk; and 3) Treatment 2 plus exogenous T along with the E2. In Experiment 4, 6 female cynomolgus macaques were treated with large doses of T for 10 days prior to E2B. Serum levels of T and E2 were quantified by radioimmunoassay; LH by bioassay. In Experiment 1, LH decreased from 5.20 +/- 0.95 micrograms/ml (mean +/- SEM) to 0.47 +/- 0.04 micrograms/ml. In Experiment 2, E2 pretreatment depressed LH and T, and these animals responded to E2B with an increase in LH. Replacement of T (Experiment 3) did not inhibit positive feedback. Intact females treated with T responded to E2B with an increase in LH. These results suggest that a testicular product other than T is involved in the inhibition of the positive feedback response to E2B in intact male macaques, and that E2 pretreatment overcomes this effect.

This article has been cited by other articles:

				J. A. Resko, A. C. Pereyra-Martinez, H. L. Stadelman, and C. E. Roselli Cellular Observations and Hormonal Correlates of Feedback Control of Luteinizing Hormone Secretion by Testosterone in Long-Term Castrated Male Rhesus Monkeys Biol Reprod, September 1, 2000; 63(3): 872 - 878. [Abstract] [Full Text]

				M. Baum, R. Carroll, M. Erskine, and S. Tobet Neuroendocrine response to estrogen and sexual orientation Science, November 22, 1985; 230(4728): 960 - 961. [PDF]