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Home / Equine Research Bank / Domest Anim Endocrinol / Circadian and circannual rhythms of cortisol, ACTH, and &#x3...
Domestic animal endocrinology2012; 43(4); 317-324; doi: 10.1016/j.domaniend.2012.05.005

Circadian and circannual rhythms of cortisol, ACTH, and α-melanocyte-stimulating hormone in healthy horses.

Abstract: Cosinor analysis was used to evaluate whether pituitary and adrenal hormones exhibit circadian rhythmicity in horses. The effect of season and animal age on their respective rhythms was also determined. In addition, the usefulness of evaluating cortisol rhythmicity for the diagnosis of pituitary pars intermedia dysfunction (PPID) was assessed. Serum cortisol concentrations (P < 0.01), but not plasma ACTH or α-melanocyte-stimulating hormone (α-MSH), showed a significant circadian periodicity in horses. An effect of season on hormone concentration was observed with plasma ACTH and α-MSH concentration greater in the fall and cortisol concentration greater in the spring (P < 0.001). Age did not affect cortisol rhythm, but it did blunt the variation in cortisol concentration in horses, similar to what has been previously reported to occur in aged people and dogs. In addition, our results suggest that clinically and diagnostically normal, non-PPID-affected horses commonly have a loss of cortisol diurnal rhythm. Therefore, measurement of circadian rhythm is not an appropriate diagnostic test for PPID.
Copyright © 2012 Elsevier Inc. All rights reserved.
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Publication Date: 2012-05-27 PubMed ID: 22717182DOI: 10.1016/j.domaniend.2012.05.005Google Scholar: Lookup
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  • Comparative Study
  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research investigates the daily and yearly rhythms of certain hormones related to stress and pituitary function in healthy horses, and also assesses the usefulness of these rhythms for diagnosing a common pituitary disorder.

Study Objective

  • The study aimed to understand the daily (circadian) and yearly (circannual) rhythms in hormones cortisol, adrenocorticotropic hormone (ACTH), and alpha-melanocyte-stimulating hormone (α-MSH) in horses. The effects of season and animal age on these rhythms were also explored. Moreover, researchers examined whether measuring cortisol rhythm could help diagnose pituitary pars intermedia dysfunction (PPID), a common hormonal disorder in horses.

Methodology

  • The Cosinor method, a statistical technique used for the analysis of rhythmic biological phenomena, was employed. This approach helped determine whether cortisol, ACTH, and α-MSH exhibit a daily rhythmicity in horses.

Key Findings

  • The study found that cortisol levels, but not ACTH or α-MSH, show a significant daily rhythm in horses.
  • Season significantly affected hormone levels. ACTH and α-MSH were found to be higher in the fall, while cortisol concentration was greater in the spring.
  • Age did not influence the daily rhythm of cortisol. However, it did reduce the variation in cortisol levels, similar to earlier findings in aged people and dogs.
  • Additionally, the study discovered that even horses without PPID often have a loss of daily cortisol rhythm. Hence, measuring this hormone’s rhythm was deemed unsuitable as a diagnostic tool for PPID.

Implications

  • These findings contribute to the understanding of hormone rhythms in horses, providing insights that could upgrade veterinary care in the handling of aged horses and those affected by seasonal changes.
  • However, the research also shows the limitations of using cortisol rhythm as a diagnostic tool for hormonal disorders like PPID, indicating the need for more accurate diagnostic approaches.

Cite This Article

APA
Cordero M, Brorsen BW, McFarlane D. (2012). Circadian and circannual rhythms of cortisol, ACTH, and α-melanocyte-stimulating hormone in healthy horses. Domest Anim Endocrinol, 43(4), 317-324. https://doi.org/10.1016/j.domaniend.2012.05.005

Publication

Domestic animal endocrinology
ISSN: 1879-0054
NlmUniqueID: 8505191
Country: United States
Language: English
Volume: 43
Issue: 4
Pages: 317-324
PII: S0739-7240(12)00063-X

Researcher Affiliations

Cordero, M
  • Department of Physiological Sciences, Center of Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74074, USA.
Brorsen, B W
    McFarlane, D

      MeSH Terms

      • Adrenocorticotropic Hormone / blood
      • Animals
      • Circadian Rhythm
      • Female
      • Horse Diseases / blood
      • Horses / blood
      • Hydrocortisone / blood
      • Male
      • Periodicity
      • Pituitary Diseases / blood
      • Pituitary Diseases / veterinary
      • Pituitary Gland, Intermediate
      • Reference Values
      • Seasons
      • alpha-MSH / blood

      Citations

      This article has been cited 23 times.
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