Exercise-induced increases in inflammatory cytokines in muscle and blood of horses
Version of Record online: 8 NOV 2010
© 2010 EVJ Ltd
Equine Veterinary Journal
Special Issue: Proceedings of the 8th International Conference on Equine Exercise Physiology
Volume 42, Issue Supplement s38, pages 280–288, November 2010
How to Cite
LIBURT, N. R., ADAMS, A. A., BETANCOURT, A., HOROHOV, D. W. and McKEEVER, K. H. (2010), Exercise-induced increases in inflammatory cytokines in muscle and blood of horses. Equine Veterinary Journal, 42: 280–288. doi: 10.1111/j.2042-3306.2010.00275.x
- Issue online: 8 NOV 2010
- Version of Record online: 8 NOV 2010
- [Paper received for publication 10.01.10; Accepted 23.06.10]
Reasons for performing study: Studies have demonstrated increases in mRNA expression for inflammatory cytokines following exercise in horses and have suggested those markers of inflammation may play a role in delayed onset muscle soreness. However, measurement of mRNA expression in white blood cells is an indirect method. No studies to date have documented the cytokine response to exercise directly in muscle in horses.
Hypothesis: This study tested the hypothesis that exercise increases cytokine markers of inflammation in blood and muscle.
Methods: Blood and muscle biopsies were obtained from 4 healthy, unfit Standardbred mares (∼500 kg). The randomised crossover experiment was performed with the investigators performing the analysis blind to the treatment. Each horse underwent either incremental exercise test (GXT) or standing parallel control with the trials performed one month apart. During the GXT horses ran on a treadmill (1 m/s increases each min until fatigue, 6% grade). Blood and muscle biopsies were obtained 30 min before exercise, immediately after exercise and at 0.5, 1, 2, 6 and 24 h post GXT or at matched time points during the parallel control trials. Samples were analysed using real time-PCR for measurement of mRNA expression of interferon-gamma (IFN-gamma), tumour necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and interleukin-1 (IL-1). Data were analysed using t tests with the null hypothesis rejected when P<0.10.
Results: There were no changes (P>0.10) in IL-1, IL-6, IFN-gamma or TNF-alpha during control. Exercise induced significant increases in IFN-gamma, IL1 and TNF-alpha in blood and significant increases in IFN-gamma, IL-6 and TNF-alpha in muscle. There were no significant changes in mRNA expression of IL-1 in muscle or IL-6 in blood following the GXT. These cytokine markers of inflammation all returned to preGXT levels by 24 h post GXT.
Conclusion: High intensity exercise results in a transient increase in the expression of inflammatory cytokines in muscle and blood.