title: Exercise training attenuates postoperative pain and expression of cytokines and N-methyl-D-aspartate receptor subunit 1 in rats.
abstract: BACKGROUND
  Exercise creates a variety of psychophysical effects, including altered pain perception. We investigated whether physical exercise reduces postincisional pain and cytokine and N-methyl-D-aspartate receptor 1 (NR1) expression in a rat model of skin/muscle incision and retraction (SMIR)-evoked pain.
  
  
  METHODS
  Male Sprague-Dawley rats were divided randomly into 4 groups: sham operated, SMIR-sedentary (SS), SMIR-exercise, and sham operated-exercise. On postoperative day 8, trained rats started to run on a treadmill 55 min/d with an intensity of 18 meter/minute (m/min), 5 days per week for 4 weeks. NR1, tumor necrosis factor α (TNF-α), and interleukin 6 (IL-6) expressions in the spinal cord as well as mechanical hypersensitivity following SMIR surgery were assessed for 6 to 35 days.
  
  
  RESULTS
  On postoperative day 6, SMIR-sedentary rats exhibited a marked hypersensitivity to von Frey stimuli. By contrast, SMIR-operated rats undergoing exercise demonstrated a quick recovery of mechanical hypersensitivity. The levels of TNF-α, IL-6, and NR1 in the spinal cord were significantly increased in SS rats when compared with sham-operated rats on postoperative days 6, 21, and 35 after SMIR surgery. After the 4-week exercise intervention, the SMIR-exercise group showed lower NR1, TNF-α, and IL-6 expression in the spinal cord than those in the SS group.
  
  
  CONCLUSIONS
  These results suggest that exercise training decreases persistent postsurgical pain caused by SMIR surgery. There appears to be a protective effect, probably relating to the decrease of NR1, TNF-α, and IL-6 expression in the spinal cord of SMIR rats, after exercise intervention.
authors: Department of Physical Therapy, China Medical University, Taichung, Taiwan.
authors: Yu-Wen
authors: YW
authors: Chen
authors: Min-Fei
authors: MF
authors: Lin
authors: Yu-Chung
authors: YC
authors: Chen
authors: Ching-Hsia
authors: CH
authors: Hung
authors: Jann-Inn
authors: JI
authors: Tzeng
authors: Jhi-Joung
authors: JJ
authors: Wang
mesh_terms: D000818:Animals; D016207:Cytokines / Q000378:metabolism*; D004195:Disease Models, Animal; D015536:Down-Regulation; D015850:Interleukin-6 / Q000378:metabolism; D008297:Male; D010147:Pain Measurement; D058748:Pain Perception; D017288:Pain Threshold; D010149:Postoperative Pain / Q000378:metabolism / Q000503:physiopathology / Q000517:prevention & control* / Q000523:psychology; D005082:Physical Exertion; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism*; D012420:Running; D013116:Spinal Cord / Q000378:metabolism* / Q000503:physiopathology; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D016207:Cytokines; D015850:Interleukin-6; D016194:Receptors, N-Methyl-D-Aspartate; D014409:Tumor Necrosis Factor-alpha