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Inhibin-A and inhibin-B in cyclic and pregnant mares, and mares with granulosa-theca cell tumors: Physiological and diagnostic implications.
Abstract: Studies in mares have examined serum inhibin concentrations using immuno-assays unable to distinguish dimeric inhibin-A from inhibin-B isoforms. Inhibin-A and inhibin-B immuno-assays were used to investigate concentrations in cyclic mares, young and old (6 vs 19 years old, respectively) mares following hemi-ovariectomy, mares during pregnancy and in mares with confirmed granulosa cell tumors (GCTs). Mares with inter-ovulatory intervals of 26 days had ovulatory peaks of inhibin-A averaging 80 pg/mL with a mid-cycle nadir of 5 pg/mL. Inhibin-A and inhibin-B concentrations were highly correlated (r = + 0.79, P < 0.01) though peak and nadir concentrations of inhibin-B were not significantly different. However, the ratio of inhibin-A to inhibin-B (A/B) changed significantly through the cycle, highest at ovulation and <1 (more inhibin-B than -A) at mid-cycle. Two mares with grossly extended inter-ovulatory intervals demonstrated mid-cycle inhibin-A (and inhibin-B) excursions suggestive of follicular waves. Follicle-stimulating hormone was negatively correlated with inhibin-A and -B concentrations in all 6 mares. Hemi-ovariectomy in young mares resulted in a significant decrease in inhibin-A and inhibin-B concentrations one day later (P < 0.05) but older mares did not, suggesting a possible extra-ovarian source(s) of these hormones. Both inhibin isoforms dropped to very low levels during pregnancy (P < 0.0001), inhibin-A (P < 0.0001) more rapidly than -B (P < 0.05), so that inhibin-B became the predominant measured form throughout most of gestation (P < 0.05). Mares with confirmed GCTs had elevated inhibin-B concentrations more reliably than inhibin-A but neither inhibin-A or -B was correlated with anti-Müllerian hormone concentrations. Collectively, concentrations of inhibin-A and -B were aligned with physiological events in healthy mares, though more pronounced cyclic changes were seen with inhibin-A. Inhibin-B concentrations were significantly associated with GCTs (P < 0.01), inhibin-A concentrations were not. While both inhibin-A and -B concentrations track physiological events such as cyclic follicular activity, only inhibin-B concentrations effectively signal ovarian neoplasia in mares.
Copyright © 2017 Elsevier Inc. All rights reserved.
Publication Date: 2017-12-07 PubMed ID: 29227911DOI: 10.1016/j.theriogenology.2017.12.003Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
Summary
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The research discusses the study on serum inhibin concentrations in mares, namely inhibin-A and inhibin-B, in various physiological conditions like cyclic changes, pregnancy, and presence of granulosa cell tumors.
Study Overview
- The research has explored the concentrations of inhibin hormones (inhibin-A and inhibin-B) present in mares under diverse conditions such as cyclic changes, after hemi-ovariectomy, during pregnancy, and in cases with granulosa cell tumors (GCTs).
- The main objective was to differentiate between inhibin-A and inhibin-B isoforms and study their role in various physiological events. The research also examined if these hormone levels could act as a signal for ovarian neoplasia in mares.
Findings
- While studying cyclic mares, it was found the concentration of both inhibin -A and inhibin-B were correlated with each other. However, the ratio of inhibin-A to inhibin-B changed considerably throughout the cycle.
- Upon conducting hemi-ovariectomy on young mares, there was a significant decrease in the concentration of these hormones one day later. However, the same was not observed in older mares, suggesting a possible extra-ovarian source of these hormones.
- Both inhibin isoforms dropped to very low levels during pregnancy, specifically inhibin-A levels dropped more rapidly than inhibin-B, hence, inhibin-B became the dominant form during most of the gestation period.
- Mares with confirmed GCTs had heightened levels of inhibin-B concentration more reliably than inhibin-A. But, neither inhibin-A nor -B was correlated with anti-Müllerian hormone concentrations.
Conclusions
- The research concluded that concentrations of inhibin-A and -B were in alignment with physiological events in healthy female mares, though more apparent cyclic changes were seen with inhibin-A.
- In comparison to inhibin-A concentrations, inhibin-B levels displayed a significant association with the presence granulosa cell tumors in the mare ovaries. Therefore, the study highlights that while both inhibin-A and -B concentrations track physiological events such as cyclic follicular activity, only inhibin-B concentrations effectively signal ovarian neoplasia in mares.
Cite This Article
APA
Conley AJ, Scholtz EL, Dujovne G, Cotterman RF, Legacki EL, Uliani RC, Alvarenga MA, Ball BA, Kalra B, Savjani GV, Kumar A.
(2017).
Inhibin-A and inhibin-B in cyclic and pregnant mares, and mares with granulosa-theca cell tumors: Physiological and diagnostic implications.
Theriogenology, 108, 192-200.
https://doi.org/10.1016/j.theriogenology.2017.12.003 Publication
Researcher Affiliations
- Department of Population Health & Reproduction, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA. Electronic address: ajconley@ucdavis.edu.
- Department of Population Health & Reproduction, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA.
- Department of Population Health & Reproduction, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA.
- Department of Population Health & Reproduction, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA.
- Department of Population Health & Reproduction, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA.
- Department of Animal Reproduction and Veterinary Radiology, Sao Paulo State University, UNESP, Botucatu, Brazil.
- Department of Animal Reproduction and Veterinary Radiology, Sao Paulo State University, UNESP, Botucatu, Brazil.
- Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington KY, USA.
- Ansh Labs LLC, Webster, TX, USA.
- Ansh Labs LLC, Webster, TX, USA.
- Ansh Labs LLC, Webster, TX, USA.
MeSH Terms
- Age Factors
- Animals
- Anti-Mullerian Hormone / blood
- Female
- Horses / metabolism
- Horses / physiology
- Inhibins / blood
- Pregnancy
- Pregnancy, Animal / metabolism
- Reference Values
Citations
This article has been cited 3 times.- de la Fuente A, Scoggin C, Bradecamp E, Martin-Pelaez S, van Heule M, Troedsson M, Daels P, Meyers S, Dini P. Transcriptome Signature of Immature and In Vitro-Matured Equine Cumulus-Oocytes Complex. Int J Mol Sci 2023 Sep 6;24(18).
- Drozdzewska K, Gehlen H. Markers for internal neoplasia in the horse. Vet Med Sci 2023 Jan;9(1):132-143.
- Zou G, Ren B, Liu Y, Fu Y, Chen P, Li X, Luo S, He J, Gao G, Zeng Z, Xiong W, Li G, Huang Y, Xu K, Zhang W. Inhibin B suppresses anoikis resistance and migration through the transforming growth factor-β signaling pathway in nasopharyngeal carcinoma. Cancer Sci 2018 Nov;109(11):3416-3427.
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