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Biology of reproduction2002; 68(1); 328-335; doi: 10.1095/biolreprod.102.003749

Localization and secretion of inhibins in the equine fetal ovaries.

Abstract: To clarify the source of inhibins in equine female fetuses, concentrations of immunoreactive (ir-) inhibin, inhibin pro-alphaC, and inhibin A in both fetal and maternal circulation and in fetal ovaries were measured. In addition, the localization of inhibin alpha and inhibin/activin beta(A), and beta(B) subunits and the expression of inhibin alpha(A) and inhibin/activin beta(A) subunit mRNA in fetal ovaries were investigated using immunohistochemistry and in situ hybridization. Concentrations of circulating ir-inhibin, inhibin pro-alphaC, and inhibin A were remarkably more elevated in the fetal than in the maternal circulation between Days 100 and 250 of gestation. Fetal ovaries contained large amounts of ir-inhibin, inhibin pro-alphaC, and inhibin A. In contrast, these inhibin forms were undetectable in both the maternal ovaries and placenta. The inhibin alpha and inhibin/activin beta(A) and beta(B) subunit proteins were localized to enlarged interstitial cells of the equine fetal ovary. Expression of inhibin alpha and inhibin/activin beta(A) subunit mRNAs were also observed in the interstitial cells. We conclude that the main source of large amounts of inhibins in fetal circulation is interstitial cells of fetal ovary and is not of maternal origin. Furthermore, these inhibins may play some important physiological roles in the development of gonads in the equine fetus.
Publication Date: 2002-12-21 PubMed ID: 12493730DOI: 10.1095/biolreprod.102.003749Google Scholar: Lookup
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  • Journal Article
  • Research Support
  • Non-U.S. Gov't

Summary

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This research article investigates the source of inhibins in horse fetuses, discovering that these chemicals are produced by interstitial cells in the fetal ovary rather than being produced maternally. This finding could have important implications for understanding how the development of reproductive organs in equine fetuses is regulated.

Research Objective and Methods

The study was conducted to identify the source of inhibins in equine fetuses. The methodological approach used to achieve this objective involved measuring concentrations of various forms of inhibin in both fetal and maternal circulation systems and fetal ovaries. The research also examined the location of different inhibin subunits and expression of associated mRNA using immunohistochemistry and in situ hybridization.

  • Immunoreactive inhibin, inhibin pro-alphaC, and inhibin A were the specific forms of inhibin targeted in these investigations.
  • The focus was on fetal and maternal samples collected between 100 and 250 days of gestation, a critical developmental period.

Key Findings

The research found that levels of immunoreactive inhibin, inhibin pro-alphaC, and inhibin A were significantly higher in the fetal circulation as opposed to the maternal circulation during the specified gestational period.

  • The fetal ovaries contained high amounts of the investigated forms of inhibin.
  • Contrary to this, these inhibin forms were not detectable in either the maternal ovaries or the placenta.

Protein Localization and mRNA Expression

The study further revealed that inhibin alpha and inhibin/activin beta(A) and beta(B) subunit proteins were found in the enlarged interstitial cells of the equine fetal ovary.

  • The expression of inhibin alpha and inhibin/activin beta(A) subunit mRNAs paralleled this protein localization, also observed in the interstitial cells.

Conclusion and Implication

From these findings, the researchers concluded that the main source of inhibins in fetal circulation is the interstitial cells of the fetal ovary, not of maternal origin. This has implications for understanding the physiological roles inhibins play in the development of fetal gonads, potentially influencing future reproductive health studies in equines.

Cite This Article

APA
Tanaka Y, Taniyama H, Tsunoda N, Herath CB, Nakai R, Shinbo H, Nagamine N, Nambo Y, Nagata S, Watanabe G, Groome NP, Taya K. (2002). Localization and secretion of inhibins in the equine fetal ovaries. Biol Reprod, 68(1), 328-335. https://doi.org/10.1095/biolreprod.102.003749

Publication

ISSN: 0006-3363
NlmUniqueID: 0207224
Country: United States
Language: English
Volume: 68
Issue: 1
Pages: 328-335

Researcher Affiliations

Tanaka, Yumiko
  • Department of Basic Veterinary Science, The United Graduate School of Veterinary Science, Gifu University, Gifu 501-1193, Japan.
Taniyama, Hiroyuki
    Tsunoda, Nobuo
      Herath, Chandana B
        Nakai, Rie
          Shinbo, Hiromi
            Nagamine, Natsuko
              Nambo, Yasuo
                Nagata, Shun-Ichi
                  Watanabe, Gen
                    Groome, Nigel P
                      Taya, Kazuyoshi

                        MeSH Terms

                        • Animals
                        • Female
                        • Fetus / metabolism
                        • Horses / anatomy & histology
                        • Horses / physiology
                        • Inhibin-beta Subunits / genetics
                        • Inhibin-beta Subunits / metabolism
                        • Inhibins / genetics
                        • Inhibins / metabolism
                        • Maternal-Fetal Exchange
                        • Organ Size
                        • Ovary / anatomy & histology
                        • Ovary / metabolism
                        • Pregnancy
                        • RNA, Messenger / genetics
                        • RNA, Messenger / metabolism

                        Citations

                        This article has been cited 4 times.
                        1. 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.
                          doi: 10.1294/jes.32.39pubmed: 34220270google scholar: lookup
                        2. 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.
                          doi: 10.1292/jvms.20-0174pubmed: 34135243google scholar: lookup
                        3. 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.
                          doi: 10.1294/jes.22.9pubmed: 24833982google scholar: lookup
                        4. 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.
                          doi: 10.1385/ENDO:28:2:171pubmed: 16388090google scholar: lookup