Testicular secretion of inhibin in stallions.
Abstract: In this study, clear seasonal changes in the circulating concentrations of immunoreactive inhibin were observed in stallions throughout the year. The highest plasma concentrations of immunoreactive inhibin were observed during the breeding season and the lowest concentrations were observed during the nonbreeding season. There was positive correlation between the circulating concentrations of immunoreactive inhibin, steroid hormones and gonadotrophins. Inhibin alpha subunit positive staining was observed in Sertoli cells and more clearly in Leydig cells. Both cell types also stained positively for inhibin betaA and betaB subunits. Immunoreactivity to 3beta-hydroxysteroid dehydrogenase and aromatase was observed in the Leydig cells only. The testes contained large amounts of inhibin pro-alphaC and small amounts of inhibins A and B, and the inhibin B content was higher than the inhibin A content. These results indicate that inhibin B is the major bioactive form of inhibin in equine testes. However, only inhibin pro-alphaC was detectable in the circulation and the inhibin pro-alphaC concentrations changed with the concentrations of immunoreactive inhibin. In conclusion, both Leydig and Sertoli cells secrete testicular inhibin in stallions. The positive correlation observed between plasma immunoreactive inhibin and inhibin pro-alphaC concentrations and testicular activity during the breeding and nonbreeding seasons indicates that the plasma concentrations of these hormones are potentially useful indicators of testicular activity in stallions.
Publication Date: 2000-01-01 PubMed ID: 20681114
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This research investigates the seasonal fluctuations of inhibin, a hormone produced by testes, in stallions and the relationship of these levels with other hormones and testicular activity. The findings suggest that plasma concentrations of this hormone could be used as indicators of testicular activity in stallions.
Overview of the Research
- The study focused on the level of a hormone known as immunoreactive inhibin in stallions and observed that it underwent seasonal fluctuations throughout the year.
- The levels of this hormone were the highest during the breeding season, while its levels dropped during the nonbreeding season.
Correlation with other Hormones
- There was also a positive correlation between the levels of immunoreactive inhibin and other steroid hormones and gonadotropins, which indicates that the levels of these hormones directly affect each other.
Role of Inhibin, Steroid Hormones, and Gonadotropins
- Two types of cells, Leydig cells and Sertoli cells, stained positively for Inhibin alpha subunit, Inhibin beta A, and Inhibin beta B subunits.
- Only Leydig cells, however, responded to 3beta-hydroxysteroid dehydrogenase and aromatase – enzymes that are involved in the synthesis of steroid hormones.
Inhibin in the Testes
- The testes had large amounts of inhibin pro-alphaC and smaller amounts of inhibins A and B. Among these, Inhibin B content was higher than Inhibin A.
- This led the researchers to conclude that inhibin B is the primary active form of inhibin in stallion’s testes.
Measurement of Inhibin
- Although the testes had both inhibin A and B, in circulation only inhibin pro-alphaC was detectable. Furthermore, the concentration of this hormone changed in sync with the fluctuating levels of immunoreactive inhibin.
Conclusion
- Both Leydig and Sertoli cells secrete testicular inhibin in stallions. The researchers also observed a positive correlation between plasma immunoreactive inhibin levels and inhibin pro-alphaC concentrations and testicular activity.
- This led to the conclusion that tracking the plasma concentrations of these hormones could act as useful indicators of testicular activity in stallions, particularly across different seasons.
Cite This Article
APA
Taya K, Nagata S, Tsunoda N, Nagamine N, Tanaka Y, Nagaoka K, Taniyama H, Nambo Y, Watanabe G.
(2000).
Testicular secretion of inhibin in stallions.
J Reprod Fertil Suppl(56), 43-50.
Publication
Researcher Affiliations
- Laboratory of Veterinary Physiology, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan.
MeSH Terms
- Animals
- Gene Expression Regulation / physiology
- Gonadal Steroid Hormones / blood
- Horses / blood
- Horses / metabolism
- Inhibins / blood
- Inhibins / genetics
- Inhibins / metabolism
- Male
- Protein Subunits
- Seasons
- Testis / metabolism
- Time Factors
Citations
This article has been cited 2 times.- Shakeel M, Yoon M. Functions of somatic cells for spermatogenesis in stallions.. J Anim Sci Technol 2022 Jul;64(4):654-670.
- Dhakal P, Tsunoda N, Nakai R, Kitaura T, Harada T, Ito M, Nagaoka K, Toishi Y, Taniyama H, Gen W, Taya K. Annual Changes in Day-length, Temperature, and Circulating Reproductive Hormones in Thoroughbred Stallions and Geldings.. J Equine Sci 2011;22(2):29-36.
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