Progesterone and testosterone in combination act in the hypothalamus of castrated rams to regulate the secretion of LH

Turner, A.I., Tilbrook, A.J., Clarke, I.J. and Scott, C.J. 2001, Progesterone and testosterone in combination act in the hypothalamus of castrated rams to regulate the secretion of LH, Journal of endocrinology, vol. 169, no. 2, pp. 291-298, doi: 10.1677/joe.0.1690291.

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Title Progesterone and testosterone in combination act in the hypothalamus of castrated rams to regulate the secretion of LH
Author(s) Turner, A.I.ORCID iD for Turner, A.I.
Tilbrook, A.J.
Clarke, I.J.
Scott, C.J.
Journal name Journal of endocrinology
Volume number 169
Issue number 2
Start page 291
End page 298
Total pages 8
Publisher Endocrine Society
Place of publication London, Eng.
Publication date 2001-05
ISSN 0022-0795
Keyword(s) Science & Technology
Life Sciences & Biomedicine
Endocrinology & Metabolism
Summary We tested the hypotheses that progesterone enhances the negative feedback actions of testosterone in rams and that this occurs through actions at the hypothalamus. In the first part of this study, blood samples were collected every 10 min for 12 h before and after 7 days of treatment (i.m.) of castrated Romney Marsh rams (n=5 per group) with vehicle, progesterone (4 mg/12 h), testosterone (4 mg/12 h) or a combination of progesterone (4 mg/12 h) and testosterone (4 mg/12 h). In the second part of this study the brains of four gonad-intact Romney Marsh rams were collected, the hypothalamus was sectioned and in situ hybridisation of mRNA for progesterone receptors conducted. After 7 days of treatment with vehicle or progesterone or testosterone alone, there were no changes in the secretion of LH. In contrast, treatment with a combination of progesterone and testosterone resulted in a significant (P<0.01, repeated measures ANOVA) decrease in mean plasma concentrations of LH, the number of LH pulses per hour and the pre-LH pulse nadir and a significant (P<0.01) increase in the inter-LH pulse interval. We found cells containing mRNA for progesterone receptors throughout the hypothalamus, including the preoptic area (where most GnRH neurons are located in sheep), the periventricular, ventromedial and arcuate nuclei and the bed nucleus of the stria terminalis. This study shows that progesterone is capable of acting centrally with testosterone to suppress the secretion of LH in castrated rams and that cells containing mRNA for progesterone receptors are located in the hypothalamus of rams in the vicinity of GnRH neurons.
Language eng
DOI 10.1677/joe.0.1690291
Field of Research 111404 Reproduction
110306 Endocrinology
1103 Clinical Sciences
0707 Veterinary Sciences
0702 Animal Production
Socio Economic Objective 920114 Reproductive System and Disorders
HERDC Research category C1.1 Refereed article in a scholarly journal
ERA Research output type C Journal article
Copyright notice ©2001, Endocrine Society
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