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Endocrinology1991; 128(1); 65-72; doi: 10.1210/endo-128-1-65

The effect of acute exercise on the secretion of corticotropin-releasing factor, arginine vasopressin, and adrenocorticotropin as measured in pituitary venous blood from the horse.

Abstract: We have used the technique which we have developed for collecting pituitary venous blood from conscious, undisturbed horses to study the effect of acute vigorous exercise on the secretion of CRF, arginine vasopressin (AVP) and ACTH. Pituitary venous (pit) blood was collected every 1-5 min from nine trained racehorses at rest in the stable. The horses then trotted quietly for 10 min, after which they galloped as fast as possible for 4-6 min, before returning to the stable where sampling continued. In Exp 1 (n = 5) no blood samples were taken during exercise, whereas in Exp 2 (n = 4), pit blood was collected every 30 sec during exercise. Immediately after exercise, significant elevations in heart rate (P less than 0.001), body temperature (P less than 0.01) and hematocrit (P less than 0.001) were observed as compared with preexercise values. Jugular cortisol levels were higher after exercise (301.9 +/- 35.2 nmol/liter; mean +/- SEM) than before (187.3 +/- 34.8; P less than 0.01; n = 9). Likewise, jugular AVP levels increased with exercise (before, 0.65 +/- 0.11 pmol/liter; after 3.2 +/- 0.6; P less than 0.01; n = 6), whereas jugular CRF was not altered by exercise (before, 0.38 +/- 0.08 pmol/liter; after, 0.93 +/- 0.31; n = 6; NS). In Exp 1, no significant changes in pit ACTH, AVP, or CRF were observed after exercise. However in Exp 2 when pit blood was sampled during exercise all horses showed an immediate and dramatic rise in ACTH (P less than 0.01) and AVP (P less than 0.005) secretion which peaked during galloping with mean fractional changes above resting levels of 23.6 +/- 9.9 for ACTH and 51.7 +/- 24.0 for AVP. After exercise pit AVP levels were not different from resting, whereas ACTH remained elevated (11.4 +/- 6.9-fold above resting levels). By contrast, pit CRF levels were not altered by exercise. In both experiments together, pit AVP and ACTH concentrations were correlated in eight of the nine horses, whereas pit CRF and ACTH concentrations were positively correlated in only one of seven horses. We conclude that acute exercise causes a transient increase in ACTH secretion which occurs synchronously with an increase in AVP secretion. CRF does not appear to play a major role in mediating the initial ACTH response to exercise.
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Publication Date: 1991-01-01 PubMed ID: 1846116DOI: 10.1210/endo-128-1-65Google Scholar: Lookup
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  • Journal Article
  • Research Support
  • Non-U.S. Gov't
  • Research Support
  • U.S. Gov't
  • P.H.S.

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 how vigorous, short-term exercise impacts the secretion of corticotropin-releasing factor (CRF), arginine vasopressin (AVP) and adrenocorticotropin (ACTH) in racehorses. The study finds that acute exercise leads to a temporary increase in AVP and ACTH secretion, but CRF levels remain unchanged.

Research Methodology

  • The research conducted involved a unique technique developed by the authors. This technique allowed for the collection of pituitary venous blood from calm, undisturbed horses.
  • The study included nine trained racehorses, which were initially observed during rest in the stable. The horses were then subjected to mild exercise – a 10-minute trot – followed by vigorous exercise – a gallop lasting between 4 and 6 minutes.
  • The effect of exercise on the secretion levels of CRF, AVP, and ACTH was examined. Blood was collected at intervals between 1-5 minutes during periods of rest and every 30 seconds during exercise.

Research Findings

  • Vigorous exercise significantly increased the heart rate, body temperature, and hematocrit of the horses. Additionally, cortisol and AVP levels in the jugular vein were higher immediately post-exercise as compared to the pre-exercise state.
  • However, concentrations of CRF, a hormone associated with stress responses, remained unchanged with exercise.
  • In the second experiment where pituitary blood samples were collected during exercise, there was a significant and rapid increase in ACTH and AVP secretion, peaking during the galloping phase.
  • Interestingly, after the exercise, the AVP levels returned to the resting state, whereas ACTH remained significantly elevated.
  • In contrast to AVP and ACTH, the levels of CRF in the pituitary blood did not change with exercise.

Conclusion

  • The findings suggest that vigorous, short-term exercise triggers an increase in AVP and ACTH secretion, however, CRF does not appear to significantly influence this initial response to exercise.
  • The correlation of AVP and ACTH concentrations in eight out of the nine horses suggests a synchronous response to acute exercise. This is in contradiction to the CRF response, which only correlated with ACTH in one out of seven horses, indicating that it may play a minor role in mediating the initial ACTH response to exercise.

Cite This Article

APA
Alexander SL, Irvine CH, Ellis MJ, Donald RA. (1991). The effect of acute exercise on the secretion of corticotropin-releasing factor, arginine vasopressin, and adrenocorticotropin as measured in pituitary venous blood from the horse. Endocrinology, 128(1), 65-72. https://doi.org/10.1210/endo-128-1-65

Publication

Endocrinology
ISSN: 0013-7227
NlmUniqueID: 0375040
Country: United States
Language: English
Volume: 128
Issue: 1
Pages: 65-72

Researcher Affiliations

Alexander, S L
  • Department of Endocrinology, Princess Margaret Hospital, Christchurch, New Zealand.
Irvine, C H
    Ellis, M J
      Donald, R A

        MeSH Terms

        • Adrenocorticotropic Hormone / blood
        • Adrenocorticotropic Hormone / metabolism
        • Animals
        • Arginine Vasopressin / blood
        • Arginine Vasopressin / metabolism
        • Body Temperature
        • Corticotropin-Releasing Hormone / blood
        • Corticotropin-Releasing Hormone / metabolism
        • Female
        • Heart Rate
        • Horses / physiology
        • Hydrocortisone / blood
        • Hydrocortisone / metabolism
        • Male
        • Physical Exertion
        • Pituitary Gland / blood supply
        • Pituitary Gland / metabolism

        Grant Funding

        • 38322 / PHS HHS

        Citations

        This article has been cited 19 times.
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