Endocrine response to exercise in young and old horses.
Abstract: Six young (mean + s.e., 5.3 +/- 0.8 years, 445 +/- 13 kg bwt) and 6 old (22.0 +/- 0.4 years, 473 +/- 18 kg bwt) Standardbred and Thoroughbred mares were used to test the hypothesis that age would alter the endocrine response to exercise. All of the mares were unconditioned but accustomed to the laboratory, to standing quietly and running on a treadmill, and to the standardised incremental exercise test (SET) used in the experiment. Two weeks prior to the experiment, each horse underwent a SET to determine maximal oxygen uptake (VO2max) and the speeds to be used in the actual experiment. A second graded exercise test (GXT) was performed without instrumentation for the measurement of plasma renin activity (PRA) and the plasma concentrations of atrial natriuretic peptide (ANP), arginine vasopressin (AVP), aldosterone (ALDO), and endothelin-1 (ET-1). Blood samples (30 ml) were collected at rest and at the end of each one minute step of the exercise test. Plasma concentrations of hormones were measured using radioimmunoassay kits. There were no differences (P > 0.05) between old vs. young mares for resting PRA (2.2 +/- 0.3 vs. 1.5 +/- 0.3 ng/ml/h), or the plasma concentrations of ANP (10.0 +/- 0.9 vs. 10.7 +/- 0.6 pg/ml); AVP (0.7 + 0.7 vs. 1.4 +/- 0.4 pg/ml); ALDO (39.2 +/- 10.3 vs. 22.7 +/- 4.6 pg/ml); or ET-1 (0.23 +/- 0.04 vs. 0.18 +/- 0.03 pg/ml). Exercise significantly increased PRA and the concentrations of ANP, AVP, and ALDO in both groups of horses; however, ET-1 was not altered (P > 0.05) by exercise in either group. There were differences (P < 0.05) between means obtained from the old and young groups for PRA (5.4 +/- 0.6 vs. 3.9 +/- 0.8 ng/ml/h and the concentrations of ANP (14.5 +/- 2.3 vs. 26.5 +/- 9.0 pg/ml), AVP (13.6 +/- 0.3 vs. 26.1 +/- 13.9 pg/ml, and ALDO (76.8 +/- 22.0 vs. 41.5 +/- 4.9 pg/ml) measured in samples obtained at the speed eliciting VO2max. These data suggest that older horses have an age-altered endocrine response to exercise.
Publication Date: 2000-02-05 PubMed ID: 10659318DOI: 10.1111/j.2042-3306.1999.tb05284.xGoogle Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research investigates the theory that a horse’s age can influence the hormonal response to exercise. The study used young and old horses, testing their hormonal responses before and after exercise, and found that older horses indeed exhibit an altered endocrine response to exercise.
Research Methodology
- Twelve horses participated in this study – six were young with an average age of 5.3 years and body weight of 445 kg, while the other six were old with an average age of 22 years and body weight of 473 kg. All horses were Standardbred and Thoroughbred mares.
- Despite not being conditioned for this specific experiment, all the horses were familiar with the research environment and able to carry out the activities involved in the exercise test.
- A standardized incremental exercise test (SET) was done two weeks before the real experiment. This test was used to determine the maximum oxygen uptake (VO2max) of the horses and set the speed parameters for the actual experiment.
- Without using any instruments, a second graded exercise test (GXT) was performed to measure plasma renin activity (PRA) and plasma concentrations of atrial natriuretic peptide (ANP), arginine vasopressin (AVP), aldosterone (ALDO), and endothelin 1 (ET-1).
Data Collection
- Blood samples were taken from the horses both at rest and after each one minute step of the exercise test. These samples were then evaluated in the lab using radioimmunoassay kits to measure hormone concentrations.
- Hormonal responses before and after the exercise test were compared for the young and old horse groups to study changes.
Results of the Study
- The endocrine response to exercise was found to be significantly different in older horses compared to the young ones. This confirms the initial hypothesis that age impacts hormone reaction to physical activity.
- At rest, there was no significant difference between young and old horses in their PRA, ANP, AVP, ALDO, and ET-1 levels.
- However, during exercise, PRA and the concentrations of ANP, AVP, and ALDO significantly increased in both groups, indicating an endocrine response to exercise. The hormone ET-1, however, did not show any significant changes in response to exercise in either group.
- Specific significant differences were noted between the young and old horses for PRA, ANP, AVP, and ALDO during exercise, with the older group registering comparatively higher values. This suggests an altered, possibly intensified, endocrine response in older horses during exercise.
This research might impact our understanding of the physiological changes during exercise in aging horses and could have potential applications in veterinary medicine and horse care. It also indicates an area where further research could be beneficial.
Cite This Article
APA
McKeever KH, Malinowski K.
(2000).
Endocrine response to exercise in young and old horses.
Equine Vet J Suppl(30), 561-566.
https://doi.org/10.1111/j.2042-3306.1999.tb05284.x Publication
Researcher Affiliations
- Department of Animal Science, Cook College, Rutgers-State University of New Jersey, New Brunswick 08901, USA.
MeSH Terms
- Aging / physiology
- Aldosterone / blood
- Animals
- Arginine Vasopressin / blood
- Atrial Natriuretic Factor / blood
- Endothelin-1 / blood
- Female
- Hormones / blood
- Horses / physiology
- Oxygen Consumption
- Physical Conditioning, Animal / physiology
- Renin / blood
Citations
This article has been cited 3 times.- Gehlen H, Shety T, El-Zahar H, Hofheinz I. Measurement of plasma endothelin-1 concentration in healthy horses and horses with cardiac disease during rest and after exercise. J Vet Med Sci 2019 Feb 28;81(2):263-268.
- Söder J, Bröjer JT, Nostell KE. Interday variation and effect of transportation on indirect blood pressure measurements, plasma endothelin-1 and serum cortisol in Standardbred and Icelandic horses. Acta Vet Scand 2012 Jun 10;54(1):37.
- Hart KA, Barton MH. Adrenocortical insufficiency in horses and foals. Vet Clin North Am Equine Pract 2011 Apr;27(1):19-34.
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