Effects of twitch contraction induced by magnetic stimulation on expression of skeletal muscle fibrosis related genes and limited range of motion in rat

Objective We examined the effects of twitch contraction induced by lumbar spinal root magnetic stimulation on immobilization-induced limited ROM and skeletal muscle fibrosis in rat soleus muscle. Design The groups included male Wistar rats (controls), rats with both bilateral ankle joints immobilized with plaster casts for 4 weeks (IM), and rats in which twitch contraction of the soleus muscle was induced by lumbar magnetic stimulation over the course of 4 weeks of immobilization (TC). Group differences in ankle dorsiflexion ROM, collagen content as determined by hydroxyproline assay, and the expression of fibrosis-related genes as determined by RT-PCR (hypoxia inducible factor-1α, α-smooth muscle actin, and types I and III collagen) in the soleus muscle were examined after the 4-week-long experiment. Results ROM in the TC group was significantly greater than that in the IM group. The hydroxyproline content and the expressions of fibrosis-related genes decreased significantly in the TC group compared to those in the IM group. No significant differences were seen in the expression of TGF-β mRNA. Conclusions These results suggest that twitch contraction induced by lumbar spinal root magnetic stimulation may reduce immobilization-induced limited ROM and skeletal muscle fibrosis. Corresponding author: Junya Sakamoto, Department of Physical Therapy, Unit of Physical and Occupational Therapy Sciences, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki 852-8520, Japan. TEL/Fax: +81-95-819-7964. E-mail: jun-saka@nagasaki-u.ac.jp Conflict of interest: None. Grant sponsor: This work was supported by a JSPS KAKEN Grant-in-Aid for Young Scientists (B) Number 24700539 from the Ministry of Education, Science, Sports and Culture (MEXT) Financial benefits to the authors: None Ethical approval: Animal care and experimental procedures were performed in accordance with the Guidelines for Animal Experimentation of Nagasaki University and were approved by the Institutional Animal Care and Use Committee. Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.

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