Effects of Twitch Contraction Induced by Magnetic Stimulation on Expression of Skeletal Muscle Fibrosis Related Genes and Limited Range of Motion in Rats.

Abstract

We examined the effects of twitch contraction induced by lumbar spinal root magnetic stimulation on immobilization-induced limited range of motion and skeletal muscle fibrosis in rat soleus muscle. The groups included male Wistar rats (controls), rats with both bilateral ankle joints immobilized with plaster casts for 4 wks (immobilization [IM]), and rats in which twitch contraction of the soleus muscle was induced by lumbar magnetic stimulation for 4 wks of immobilization (twitch contraction [TC]). Group differences in ankle dorsiflexion range of motion, collagen content as determined by hydroxyproline assay, and the expression of fibrosis-related genes as determined by reverse transcription-polymerase chain reaction (hypoxia inducible factor 1α, α-smooth muscle actin, and types I and III collagen) in the soleus muscle were examined after the 4-wk-long experiment. Range of motion 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 with those in the IM group. No significant differences were seen in the expression of transforming growth factor β mRNA. These results suggest that twitch contraction induced by lumbar spinal root magnetic stimulation may reduce immobilization-induced limited range of motion and skeletal muscle fibrosis.