Effect of chronic clenbuterol administration and exercise training on immune function in horses.
Abstract: Effects of longitudinal exercise training and acute intensive exercise (simulated race test) on immune function have not been reported in horses. Clenbuterol, a beta2-adrenergic agonist, is used to manage inflammatory airway disease in horses. This study investigated the interaction of 8 wk of exercise training with or without 12 wk of clenbuterol administration in horses. Twenty-three untrained standardbred mares (10 +/- 3 yr, Mean +/- SE) were used and divided into four experimental groups. Horses given clenbuterol plus exercise (CLENEX; n = 6) and clenbuterol alone (CLEN; n = 6) received 2.4 microg/kg BW of clenbuterol twice daily (in an average volume of 20 mL) on a schedule of 5 d on and 2 d off for 12 wk. The CLENEX group was also aerobically trained 3 d/wk. Mares given exercise alone (EX; n = 5) were aerobically trained for 3 d/wk, and the control group (CON; n = 6) remained sedentary. Both EX and CON horses were administered similar volumes (approximately 20 mL) of molasses twice daily. A simulated race test (SRT) resulted in an elevation in lymphocyte number postexercise (P < 0.05). There was no significant difference after acute exercise in either monocyte or granulocyte number. Acute exercise resulted in a decrease (P < 0.05) in the percentage of CD4+ and an increase (P < 0.05) in the percentage of CD8+ cells. The SRT resulted in a decreased lymphoproliferative response to pokeweed mitogen (P < 0.05). A SRT had no effect on antibody production in response to equine influenza vaccine. The EX group demonstrated greater cortisol concentrations at rest and at all other time points postexercise after completing the training regimen compared with CLENEX horses (P < 0.05). Preexercise (SRT) peripheral blood monocyte number was lower in CLENEX horses than in other treatment groups (P < 0.05). Clenbuterol and exercise training did not significantly affect post-SRT changes in leukocyte numbers. Exercise training resulted in a decrease (P < 0.05) in the percentage of CD8+ cells post-SRT compared with other groups, but the percentage of CD4+ cells was not altered by either clenbuterol or exercise conditioning. Lymphocyte proliferative response was not affected by clenbuterol or exercise treatment. Horses demonstrated responses to bouts of acute exercise as noted with other species, namely humans and rodents.
Publication Date: 2004-11-13 PubMed ID: 15537770DOI: 10.2527/2004.82123500xGoogle Scholar: Lookup
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- Clinical Trial
- Journal Article
Summary
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The research study examines the effects of chronic clenbuterol administration and exercise training on the immune function of horses, and concluded that the exercise training triggered changes in immune cell subsets but the administration of clenbuterol did not have a notable impact.
Research Methodology
- The study involved twenty-three standardbred mares. They were divided into four groups – one group receiving clenbuterol and exercise (CLENEX), another receiving clenbuterol alone (CLEN), one just with exercise (EX), and a control group (CON) which remained inactive.
- The CLENEX and CLEN groups were given 2.4 microg/kg BW of clenbuterol twice daily (with a schedule of 5 days on and 2 days off for 12 weeks). Only the CLENEX group was also aerobically trained three days per week. On the other hand, the EX group underwent aerobic training three days per week.
- The CON and EX horses were administered similar volumes of molasses twice daily for control purposes.
Key Findings
- Post-strain race test (SRT), an increase in lymphocyte numbers was noticed in all groups. This evidence suggests that acute exercise leads to an elevation of lymphocyte count but does not significantly affect monocyte or granulocyte numbers.
- Acute exercise also resulted in a decrease in the presence of CD4+ cells and an increase in CD8+ cells. However, neither exercise nor clenbuterol administration led to changes in the proportion of CD4+ cells after the SRT.
- The SRT led to a decline in the lymphoproliferative response to pokeweed mitogen. However, the study did not show a significant impact of the SRT on antibody production in response to equine influenza vaccine.
- Resting and post-exercise cortisol concentrations were higher in the exercise-only group when compared to the clenbuterol and exercise combined group.
- In the group receiving clenbuterol and exercise, a lower peripheral blood monocyte count was observed before the SRT compared to other groups.
- The study also found that exercise training led to a reduction in the percentage of CD8+ cells after the SRT compared to other groups.
- Exercise or clenbuterol treatments did not affect lymphocyte proliferative response.
Conclusion
- While exercise training resulted in changes in the immune cell subsets, clenbuterol administration did not significantly impact post-SRT changes in leukocyte numbers. These responses to bouts of acute exercise in horses are comparable to those seen in other species, including humans and rodents.
Cite This Article
APA
Malinowski K, Kearns CF, Guirnalda PD, Roegner V, McKeever KH.
(2004).
Effect of chronic clenbuterol administration and exercise training on immune function in horses.
J Anim Sci, 82(12), 3500-3507.
https://doi.org/10.2527/2004.82123500x Publication
Researcher Affiliations
- Equine Science Center, Dept. of Animal Science, The State University of New Jersey, New Brunswick 08901, USA.
MeSH Terms
- Adrenergic beta-Agonists / administration & dosage
- Adrenergic beta-Agonists / pharmacology
- Animals
- Clenbuterol / administration & dosage
- Clenbuterol / pharmacology
- Drug Administration Schedule
- Female
- Horses / immunology
- Hydrocortisone / blood
- Lymphocytes / drug effects
- Lymphocytes / immunology
- Physical Conditioning, Animal / physiology
- Time Factors
Citations
This article has been cited 4 times.- Witkowska-Piłaszewicz O, Pingwara R, Szczepaniak J, Winnicka A. The Effect of the Clenbuterol-β2-Adrenergic Receptor Agonist on the Peripheral Blood Mononuclear Cells Proliferation, Phenotype, Functions, and Reactive Oxygen Species Production in Race Horses In Vitro. Cells 2021 Apr 17;10(4).
- Witkowska-Piłaszewicz O, Pingwara R, Winnicka A. The Effect of Physical Training on Peripheral Blood Mononuclear Cell Ex Vivo Proliferation, Differentiation, Activity, and Reactive Oxygen Species Production in Racehorses. Antioxidants (Basel) 2020 Nov 20;9(11).
- Ohnuki Y, Umeki D, Mototani Y, Shiozawa K, Nariyama M, Ito A, Kawamura N, Yagisawa Y, Jin H, Cai W, Suita K, Saeki Y, Fujita T, Ishikawa Y, Okumura S. Role of phosphodiesterase 4 expression in the Epac1 signaling-dependent skeletal muscle hypertrophic action of clenbuterol. Physiol Rep 2016 May;4(10).
- Witkowska-Piłaszewicz O, Malin K, Dąbrowska I, Grzędzicka J, Ostaszewski P, Carter C. Immunology of Physical Exercise: Is Equus caballus an Appropriate Animal Model for Human Athletes?. Int J Mol Sci 2024 May 10;25(10).
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