Pain. 2015 Jul 30. [Epub ahead of print]
Regular physical activity prevents chronic pain by altering resident muscle macrophage phenotype and increasing IL-10 in mice.
Leung A1, Gregory NS, Allen LH, Sluka KA.
Author information
1University of Iowa Carver College of Medicine, Iowa City, IA
2University of Iowa Carver College of Medicsine, Department of Internal Medicine, Iowa City, IA
3University of Iowa Carver College of Medicine, Department of Physical Therapy and Rehabilitation Science, Iowa City, IA
4University of Iowa, Neuroscience Graduate Program, Iowa City, IA.
Abstract
Regular physical activity in healthy individuals prevents development of chronic musculoskeletal pain; however, the mechanisms underlying this exercise-induced analgesia are not well understood.
Interleukin-10(IL-10), an anti-inflammatory cytokine which can reduce nociceptor sensitization, increases during regular physical activity.
Since macrophages play a major role in cytokine production and are present in muscle tissue, we propose that physical activity alters macrophage phenotype to increase IL-10 and prevent chronic pain.
Physical activity was induced by allowing C57BL/6J mice free access to running wheels for 8 weeks and compared to sedentary mice with no running wheels.
Using immunohistochemical staining of the gastrocnemius muscle to label regulatory (M2, secretes anti-inflammatory cytokines) and classical (M1, secretes proinflammatory cytokines) macrophages, the percentage of M2-macrophages increased significantly in physically active mice (68.5+4.6% of total) compared to sedentary mice (45.8+7.1% of total).
Repeated acid injections into the muscle enhanced mechanical sensitivity of the muscle and paw in sedentary animals that does not occur in physically active mice; no sex differences occur in either sedentary or physically active mice.
Blockade of IL-10 systemically or locally prevented the analgesia in physically active mice, i.e. mice developed hyperalgesia.
Conversely, sedentary mice pretreated systemically or locally with IL-10 had reduced hyperalgesia after repeated acid injections.
Thus, these results suggest that regular physical activity increases the percentage of regulatory macrophages in muscle and that IL-10 is an essential mediator in the analgesia produced by regular physical activity.
No comments:
Post a Comment