How does the pain on the skeletal muscles influences in neuropathic models ?

2004 Fiscal Year Final Research Report Summary

• Project/Area Number: 15500364
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Rehabilitation science/Welfare engineering
• Research Institution: HIROSHIMA UNIVERSITY
• Principal Investigator: TSUTSUMI Eriko Hiroshima University, Graduate School of Health Science, Research Assistant, 大学院・保健学研究科, 助手 (40304422)
• Co-Investigator(Kenkyū-buntansha): KAWAGUCHI Koutarou Hiroshima University, Graduate School of Health Science, Instructor, 大学院・保健学研究科, 講師 (60263703)
• Project Period (FY): 2003 – 2004
• Keywords: neuropathic pain / CCI model / mouse / muscle atrophy / immobilized model

Research Abstract

In our chronic constriction injury (CCI) experiments, sets of three (instead of four) 4,0-chromic gut ligatures were performed on mice. The mechanical allodynia and the thermal induced algesia, was ante- and post-operatoly measured. Complementariry, the morphological changes in femur were roughly evaluated. C57BL/6NCrj line, 11 weeks initial age, 23±1.7g initial weight, 26 male mice were used. The changing in the behavior of CCI mice were under observation. Post-sacrifice, the changing in osteoclast population was evaluated. 1.The difference score (DS) significantly decreased, during the 8 weeks of post-operate observation. 2.In CCI legs, the number of withdrawal response to pressure, significantly increased in the first 3 weeks. 3.The amount of osteoclast in CCI legs increased. Consequently, we appreciate that C57BL/6NCrj line is fully qualified for CCI modeling. It may be necessary to improve the accuracy of osteotomy and cell staining techniques in the near future. Regarding the bon e atrophy and the changes in osteoclasts, a further comparison between CCI and other models would be useful.
The next experiment was done in order to find the contribution of post-operatory immobilization (IM) in the atrophy process. The morphological and histo-enzymological changes were compared. C57BL/6N line, 10 weeks initial age, 21.7±1.29g initial weight, 62 male, mice were assigned in three groups, as follows : 1)23 mice CCI (CCI group) 2)17 mice IM (IM group) 3)22 mice CCI and IM(CCI+IM). The ante- and post-operatory DS numbers for each group were measured. General observation : After the first week, the DS number significantly decreased. The muscle wet weight (MW) significantly decreased in the 2-nd and the 3-rd week. Comparative results : Histo-enzymologically, in the 3-rd week, the inter-group comparative values changed as follows : a)for tibiaris anterior (TA) ; IM>CCI+IM>CCI ; b)for gastrocnemius (GC) ; IM>CCI>CCI+IM ; c)for MW ; IM>CCI>CCI+IM. Considering the CCI model, the tendency to atrophy, significantly high in the CCI and CCI+IM groups, comparing with the IM group, shows that supplementary factors can influence the evolution. Except immobilization, we suppose that inflammatory lax ligature itself might be a factor in the motor nerve partial injury. We also think that possibly, some structural changes were due to the nerve inflammation, radiating along the pain transmission channel, abnormal nerve peptides, or accumulation of other dolorific interstitial substances. We consider necessary a holistic approach to the atrophic neuropathy in the future.