The testis as a major source of circulating inhibins in the male equine fetus during the second half of gestation.
Abstract: Immunolocalization of the inhibin (a) and inhibin/activin (beta3A and betaB) subunit proteins in equine fetal testes was investigated to determine the ability of the fetal testis to produce inhibins at 120, 150, 200, and 250 days of gestation. In addition, concentrations of immunoreactive (ir)-inhibin, inhibin pro-aC, and inhibin A in both the maternal and fetal circulation were measured. It was found that plasma concentrations of ir-inhibin, inhibin pro-alphaC, and inhibin A were much higher (P < .05) in the fetal than in the maternal circulation at any stage of gestation examined. Similarly, while fetal testicular homogenate contained increased amounts of inhibins, the inhibins were undetectable in homogenates of maternal ovaries and placentae. At 120 days of gestation, all 3 subunit proteins were localized to the interstitial cells, while the immunoreactivity for the inhibin/activin 3B subunit protein was also observed in Sertoli cells. The intensity of immunoreactivity for the 3 subunit proteins in interstitial cells increased as pregnancy advanced to day 200, and, at this stage, immunoreactivity for the inhibin alpha subunit protein was observed in the fetal testes in a pattern consistent with localization in Sertoli cells. Thus, the inhibin/activin betaA subunit protein was confined to interstitial cells during the gestational periods examined. We conclude that equine fetal testes secrete large amounts of inhibins, including dimeric inhibin A and possibly other dimeric forms, such as inhibin B and activins, into the fetal circulation. These results suggest that these proteins may play some important roles in the development of fetal testes during gestation.
Publication Date: 2002-03-01 PubMed ID: 11868816
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research study investigates how the testis in the male equine fetus produces inhibins, a type of hormone protein, at different stages of gestation. The study highlight significant differences in the levels of these proteins found in fetal and maternal circulation throughout the gestational period.
Methodology of the Research
- The researchers looked at the formation of different types of inhibin subunit proteins in equine fetal testes. They picked four specific points in the gestational timeline for this investigation: 120, 150, 200, and 250 days.
- They measured the concentrations of different types of inhibins including immunoreactive (ir)-inhibin, inhibin pro-aC, and inhibin A in both maternal and fetal circulatory systems.
Findings from the Research
- The study observed that fetal circulation recorded much higher levels of the different inhibin hormones than in the maternal circulation at every stage of gestation examined.
- Fetal testicular homogenate had increased amounts of inhibins, but these hormone proteins were undetectable in homogenates derived from maternal ovaries and the placenta.
- At the 120th day of gestation, all three subunit proteins were found in the interstitial cells, a type of connective tissue cell. Additionally, the inhibin/activin betaB subunit protein also localized in the Sertoli cells, cells that support and nourish the developing sperm cells.
- The intensity of reactivity for the three subunit hormone proteins in the interstitial cells increased as pregnancy progressed to day 200, with the inhibin alpha subunit protein showing specific patterns in fetal testes indicating localization in Sertoli cells.
- The inhibin/activin betaA subunit protein confined itself to the interstitial cells for the duration of the gestational periods studied.
Conclusions from the Study
- Based on the observable data, the researchers concluded that equine fetal testes secrete large amounts of inhibins, including dimeric inhibin A and possibly other dimeric forms like inhibin B and activins into the fetal circulation.
- The researchers suggest that the hormone proteins may have significant roles in the development of fetal testes during gestation.
Cite This Article
APA
Tanaka Y, Taniyama H, Tsunoda N, Shinbo H, Nagamine N, Nambo Y, Nagata S, Watanabe G, Herath CB, Groome NP, Taya K.
(2002).
The testis as a major source of circulating inhibins in the male equine fetus during the second half of gestation.
J Androl, 23(2), 229-236.
Publication
Researcher Affiliations
- Department of Basic Veterinary Science, The United Graduate School of Veterinary Science, Gifu University, Japan.
MeSH Terms
- Animals
- Enzyme-Linked Immunosorbent Assay
- Fetal Blood
- Fetus / metabolism
- Gestational Age
- Horses / embryology
- Immunohistochemistry
- Inhibins / blood
- Inhibins / metabolism
- Male
- Osmolar Concentration
- Protein Precursors / metabolism
- Testis / embryology
Citations
This article has been cited 7 times.- Dhakal P, Tsunoda N, Nambo Y, Taniyama H, Nagaoka K, Watanabe G, Taya K. Circulating activin A during equine gestation and immunolocalization of its receptors system in utero-placental tissues and fetal gonads. J Equine Sci 2021 Jun;32(2):39-48.
- Araki M, Ohtaki T, Kimura J, Hobo S, Taya K, Tsunoda N, Taniyama H, Tsumagari S, Nambo Y. Presence of surfactant proteins in the uteri and placentae of pregnant mares. J Vet Med Sci 2021 Jul 28;83(7):1167-1172.
- Dhakal P, Tsunoda N, Nakai R, Nagaoka K, Nambo Y, Sato F, Taniyama H, Taya K. 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 2011;22(1):9-15.
- Yang P, Medan MS, Arai KY, Jin W, Watanabe G, Taya K. Secretion of inhibin and testicular expression of inhibin subunits in male duck embryos and newly hatched ducks. Endocrine 2005 Nov;28(2):171-9.
- Li B, Nair M, Mackay DR, Bilanchone V, Hu M, Fallahi M, Song H, Dai Q, Cohen PE, Dai X. Ovol1 regulates meiotic pachytene progression during spermatogenesis by repressing Id2 expression. Development 2005 Mar;132(6):1463-73.
- Medan MS, Nambo Y, Nagamine N, Shinbo H, Watanabe G, Groome N, Taya K. Plasma concentrations of ir-inhibin, inhibin A, inhibin pro-alphaC, FSH, and estradiol-17beta during estrous cycle in mares and their relationship with follicular growth. Endocrine 2004 Oct;25(1):7-14.
- 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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