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1 September 2000 Cellular Observations and Hormonal Correlates of Feedback Control of Luteinizing Hormone Secretion by Testosterone in Long-Term Castrated Male Rhesus Monkeys
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Abstract

Testosterone at physiological levels cannot exert negative feedback action on LH secretion in long-term castrated male monkeys. The cellular basis of this refractoriness is unknown. To study it, we compared two groups of male rhesus macaques: one group (group 1, n = 4) was castrated and immediately treated with testosterone for 30 days; the second group (group 2, n = 4) was castrated and treated with testosterone for 9 days beginning 21 days after castration. Feedback control of LH by testosterone in group 1 was normal, whereas insensitivity to its action was found in group 2. Using the endpoints of concentrations of aromatase activity (P450AROM messenger RNA [mRNA]) and androgen receptor mRNA in the medial preoptic anterior hypothalamus and in the medial basal hypothalamus, we found that aromatase activity in both of these tissues was significantly lower, P < 0.01, in group 2 compared with group 1 males. P450AROM mRNA and androgen receptor mRNA did not differ, however. Our data suggest that the cellular basis of testosterone insensitivity after long-term castration may reside in the reduced capacity of specific brain areas to aromatize testosterone. Because P450AROM mRNA did not change in group 2 males, we hypothesize that an estrogen-dependent neural deficit, not involving the regulation of the P450AROM mRNA, occurs in long-term castrated monkeys.

John A. Resko, Ada C. Pereyra-Martinez, Henry L. Stadelman, and Charles E. Roselli "Cellular Observations and Hormonal Correlates of Feedback Control of Luteinizing Hormone Secretion by Testosterone in Long-Term Castrated Male Rhesus Monkeys," Biology of Reproduction 63(3), 872-878, (1 September 2000). https://doi.org/10.1095/biolreprod63.3.872
Received: 26 January 2000; Accepted: 1 April 2000; Published: 1 September 2000
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