Post-Natal Dynamic Changes in Circulating Follicle-Stimulating Hormone, Luteinizing Hormone, Immunoreactive Inhibin, Progesterone, Testosterone and Estradiol-17β in Thoroughbred Colts until 6 Months of Age.
Abstract: The aim of present study was to clarify the post-natal profile of follicle-stimulating hormone (FSH), luteinizing hormone (LH), immunoreactive (ir)-inhibin, progesterone, testosterone, and estradiol-17β, and their relationships in Thoroughbred colts. Six hundred and thirty-six colts were used for the study. Single plasma samples from each animal were harvested from the blood drawn through jugular venipuncture. The subjects were born with high amounts of progesterone, testosterone, and estradiol-17β, all of which dropped significantly and remained at lower levels till the end of 6 months. FSH decreased transiently after birth until day 12 and then gradually increased to peak at day 100 which then maintained in lesser levels towards the end of the studied period. LH was highest during birth which decreased until day 26 and then increased slowly to sub-birth levels up to day 90. Animals were born with high amounts of ir-inhibin. It dropped slowly and halved by day 20 and then decreased towards rest of the studied period. The increase in FSH is negatively correlated with the declining ir-inhibin levels. The early increase in FSH can be the indication of early post-natal maturation of the hypothalamic pituitary testicular axis that ultimately might be responsible for priming the testes for future development.
Publication Date: 2011-04-26 PubMed ID: 24833982PubMed Central: PMC4013995DOI: 10.1294/jes.22.9Google Scholar: Lookup
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Summary
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The research investigates the post-natal development of key hormones in Thoroughbred colts (young male horses), and their relationships with each other over the first six months of life. A total of 636 colts were analyzed.
Methods
- The study uses 636 Thoroughbred colts to track post-natal hormonal changes.
- Important hormones examined in this study include follicle-stimulating hormone (FSH), luteinizing hormone (LH), immunoreactive (ir)-inhibin, progesterone, testosterone, and estradiol-17β.
- The researchers collected single plasma samples from each animal, processed from blood drawn through jugular venipuncture (a method of blood collection through a vein).
Findings
- The researchers found that the colts were born with high levels of progesterone, testosterone, and estradiol-17β, but these levels dropped significantly over the first six months after birth.
- FSH levels decreased transiently after birth until day 12 and then gradually increased to peak at day 100, maintaining at lesser levels thereafter.
- Luteinizing hormone (LH) was at its highest levels during birth, dropped until day 26, then started to rise again to reach near-birth levels by day 90.
- Colts were born with high amounts of immunoreactive (ir)-inhibin, which decreased slowly over time, halving by day 20 and continuing to decrease throughout the rest of the study period.
Correlations and Conclusions
- There was a negative correlation between rising levels of FSH and decreasing levels of ir-inhibin. In other words, as FSH went up, ir-inhibin went down.
- The researchers suggest that the early post-natal rise in FSH may indicate the maturation of the hypothalamic-pituitary-testicular axis, which might prime the testicles for future development, although further research would be needed to confirm this.
Cite This Article
APA
Dhakal P, Tsunoda N, Nakai R, Nagaoka K, Nambo Y, Sato F, Taniyama H, Taya K.
(2011).
Post-Natal Dynamic Changes in Circulating Follicle-Stimulating Hormone, Luteinizing Hormone, Immunoreactive Inhibin, Progesterone, Testosterone and Estradiol-17β in Thoroughbred Colts until 6 Months of Age.
J Equine Sci, 22(1), 9-15.
https://doi.org/10.1294/jes.22.9 Publication
Researcher Affiliations
- Department of Basic Veterinary Science, United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan ; Laboratory of Veterinary Physiology, Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan.
- Shadai Corporation, Hokkaido 059-1432, Japan.
- Department of Basic Veterinary Science, United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan ; Laboratory of Veterinary Physiology, Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan.
- Laboratory of Veterinary Physiology, Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan.
- Hidaka Training Research Center, Japan Racing Association, Hokkaido 057-0171, Japan.
- Department of Veterinary Pathology, Rakuno Gakuen University, Hokkaido 069-850, Japan.
- Department of Veterinary Pathology, Rakuno Gakuen University, Hokkaido 069-850, Japan.
- Department of Basic Veterinary Science, United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan ; Laboratory of Veterinary Physiology, Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan.
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Citations
This article has been cited 5 times.- Boakari YL, Legacki E, Alonso MA, Dos Santos ACF, Nichi M, Conley AJ, Fernandes CB. Postnatal Dynamics of Circulating Steroid Hormones in Mule and Equine Neonates. Vet Sci 2022 Oct 28;9(11).
- Katsumata E, Jaroenporn S, Ueda Y, Arai K, Katsumata H, Watanabe G, Taya K. Circulating gonadotropins and testicular hormones during sexual maturation and annual changes in male bottlenose dolphins (Tursiops truncatus). J Vet Med Sci 2017 Nov 17;79(11):1899-1905.
- Toishi Y, Tsunoda N, Kume K, Nagaoka K, Watanabe G, Taya K. PATHFAST, a novel chemiluminescent enzyme immunoassay for measuring estradiol in equine whole blood and serum. J Reprod Dev 2016 Dec 20;62(6):631-634.
- de Lara NSS, Weiss RR, Oba E, Kozicki LE, Souza FA, Bergstein-Galan TG, Muehlbauer E, Silvestri M, de Lima PHL, Vaz ES. Prediction Values for the Influence of Fetal Sex on Plasma Progesterone Concentration in Crioulo Breed Mares: A Preliminary Investigation. Reprod Domest Anim 2025 Oct;60(10):e70131.
- Ishimaru M, Kume K, Murase H, Sato F, Matsui A, Ohmura H, Taya K. Effect of birth month on endocrine function in Thoroughbred foals born in Hokkaido, the northern part of Japan. J Vet Med Sci 2025 Jul 7;87(7):804-815.
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