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Local Application of Ultrasound Attenuates Neuropathic Allodynia and Proinflammatory Cytokines in Rats After Thoracotomy
  1. Ching-Hsia Hung, PhD*,,
  2. Chong-Chi Chiu, MD,§,
  3. Chen-Chih Liu, MS* and
  4. Yu-Wen Chen, PhD,**
  1. *Department of Physical Therapy, Tainan
  2. Institute of Allied Health Sciences, College of Medicine, National Cheng Kung University, Tainan
  3. Department of General Surgery, Chi Mei Medical Center, Tainan and Liouying
  4. §Department of Electrical Engineering, Southern Taiwan University of Science and Technology, Tainan
  5. Department of Physical Therapy, College of Health Care, China Medical University, Taichung
  6. **Department of Medical Research, Chi-Mei Medical Center, Tainan, Taiwan
  1. Address correspondence to: Yu-Wen Chen, PhD, Department of Physical Therapy, College of Health Care, China Medical University, 91 Hsueh-Shih Rd, Taichung 40402, Taiwan (e-mail: cywhwok{at}mail.cmu.edu.tw).

Abstract

Background and Objectives We aimed to investigate the effect of therapeutic ultrasound (TU) on pain sensitivity and the concentration inflammatory cytokines in a thoracotomy rat model.

Methods Rats were distributed randomly into 4 groups: (1) sham operated, (2) thoracotomy and rib retraction (TRR), (3) TRR rats that received TU (TRR + TU-1), and (4) TRR rats that received TU with the ultrasound turned off (TRR + TU-0). Ultrasound was set at 1-MHz frequency (1.0-W/cm2 intensity and 100% duty cycle for 5 minutes), began on postoperative day (POD) 10, and then continued once per day, 5 days a week for 3 weeks.

Results The TRR and TRR + TU-0 rats encountered tactile hypersensitivity from PODs 10 to 28. Mechanical withdrawal thresholds were increased (all P < 0.05) following 5 days of TU, but thresholds remained significantly lower than baseline values. Therapeutic ultrasound increased the subcutaneous, but not body temperature. All groups receiving TRR demonstrated an increase in concentration of interleukin 1β and tumor necrosis factor α (TNF-α) on POD 14; however, the rise in TNF-α concentration was less in the TU-treated group than in the others. The decrease in concentration was greatest in the TRR + TU-1 group and similar between the TRR and TRR + TU-0 groups.

Conclusions Mechanical allodynia was partially resolved with TU. Tissue temperature increased with ultrasound, while TU restricted the up-regulation of interleukin 1β and TNF-α around the injured intercostal nerve.

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Footnotes

  • C.-H.H. and C.-C.L. contributed equally to this work.

    Financial support was provided by a grant from the Ministry of Science and Technology, Taiwan (MOST 105-2314-B-006-051).

    The authors declare no conflict of interest.

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