Abstract
Background Although evidence suggests that therapeutic ultrasound (TU) in combination with treadmill training (TT) suppresses nerve injury–associated pain, the molecular mechanisms for this action are not clear.
Objective The purpose of this research was to study the possible beneficial effects of TU and TT, alone and in combination, on 2 clinical indicators of neuropathic pain and correlate these findings with changes in inflammatory mediators within the spinal cord. Our experimental model used the well-known chronic constriction injury (CCI) of the rat sciatic nerve.
Design This was an experimental study.
Methods Each group contained 10 rats. Group 1 underwent only the CCI procedure. Group 2 underwent a sham operation where the sciatic nerve was exposed but not ligated. Group 3 had the sham operation followed by both TT and TU. Groups 4, 5, and 6 underwent the CCI procedure followed by TT alone, TU alone, and both the TT and TU interventions, respectively. Heat and mechanical sensitivity, interleukin-6 (IL-6), interleukin-10 (IL-10), and ionized calcium binding adaptor molecule 1 (Iba1) were evaluated.
Results Compared with group 1 animals, TT or TU, or both, produced smaller decreases in mechanical withdrawal threshold and heat withdrawal latencies. The combination of TT and TU was more effective than either treatment alone. In addition, rats that received these treatments did not express the upregulation of IL-6 and Iba1 in their spinal cords on postoperative days 14 and 28, as was found in the group 1 animals.
Limitations These experimental findings may not be generalizable to humans.
Conclusions The combination of TU and TT reduces neuropathic pain more than either modality alone. This beneficial effect appears related to downregulation of proinflammatory IL-6 and Iba1, while upregulating the anti-inflammatory IL-10.
Footnotes
Professor Hung, Ms Huang, and Professor Chen provided concept/idea/research design. Professor Chen provided writing. Ms Huang and Dr Tzeng provided data collection. Dr Tzeng and Professor Wang provided data analysis. Professor Hung and Professor Chen provided project management. Professor Hung, Dr Tzeng, Professor Wang, and Professor Chen provided facilities/equipment. Ms Huang and Professor Wang provided institutional liaisons. Professor Wang and Professor Chen provided administrative support. All authors provided consultation (including review of manuscript before submission).
The experimental protocols were approved by the Experimental Animal Committee of National Cheng Kung University in Taiwan.
Financial support was provided by a grant (CMNCKU10315) from Chi-Mei Medical Center, Tainan, Taiwan.
- Received August 29, 2014.
- Accepted April 24, 2016.
- © 2016 American Physical Therapy Association
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