High-frequency transcutaneous electrical nerve stimulation alleviates spasticity after spinal contusion by inhibiting activated microglia in rats

Suk Chan Hahm, Young Wook Yoon, Junesun Kim

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)

Abstract

Background. Transcutaneous electrical nerve stimulation (TENS) can be used as a physical therapy for spasticity, but the effects of TENS on spasticity and its underlying mechanisms remain unclear. Objective. The purpose of this study was to test the effects of TENS on spasticity and the role of activated microglia as underlying mechanisms of TENS treatment for spasticity in rats with a 50-mm contusive spinal cord injury (SCI). Methods. A spinal contusion was made at the T12 spinal segment in adult male Sprague-Dawley rats using the NYU impactor. Behavioral tests for motor function were conducted before and after SCI and before and after TENS application. To assess spasticity, the modified Ashworth scale (MAS) was used before and after SCI, high-frequency (HF)/low-frequency (LF) TENS application at 3 different intensities (motor threshold [MT], 50% and 90% MT) or minocycline administration. Immunohistochemistry for microglia was performed at the lumbar spinal segments. Results. Motor recovery reached a plateau approximately 28 days after SCI. Spasticity was well developed and was sustained above the MAS grade of 3, beginning at 28 days after SCI. HF-TENS at 90% MT significantly alleviated spasticity. Motor function did not show any significant changes with LF- or HF-TENS treatment. HF-TENS significantly reduced the proportion of activated microglia observed after SCI. Minocycline, the microglia inhibitor, also significantly alleviated spasticity with the reduction of activated microglia expression. Conclusions. These results suggest that HF-TENS at 90% MT alleviates spasticity in rats with SCI by inhibiting activated microglia.

Original languageEnglish
Pages (from-to)370-381
Number of pages12
JournalNeurorehabilitation and Neural Repair
Volume29
Issue number4
DOIs
Publication statusPublished - 2015 May 27

Bibliographical note

Funding Information:
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (MEST), 2012-0003901. It was also partially supported by a grant of the Korea University College of Health Science (K1031192). Suk-Chan Hahm was supported by a scholarship from the BK21+ Program in Embodiment: Health-Society Interaction in the Department of Public Health Science of Korea University Graduate School.

Publisher Copyright:
© The Author(s) 2014.

Keywords

  • microglia
  • spasticity
  • spinal cord injury
  • transcutaneous electrical nerve stimulation (TENS)

ASJC Scopus subject areas

  • Rehabilitation
  • Neurology
  • Clinical Neurology

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