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Early Cyclical Neuromuscular Electrical Stimulation Improves Strength and Trophism by Akt Pathway Signaling in Partially Paralyzed Biceps Muscle After Spinal Cord Injury in Rats.

Research paper by Gabriel R GR de Freitas, Caroline C do Espírito CCDE Santo, Nicolas A M M NAMM de Machado-Pereira, Franciane F Bobinski, Adair R S ARS Dos Santos, Jocemar J Ilha

Indexed on: 15 Dec '17Published on: 15 Dec '17Published in: Physical therapy



Abstract

Electrical stimulation is often used to treat weakness in people with spinal cord injury (SCI), however its efficacy to increase strength and trophism are weak and the mechanisms underlying the therapeutic benefits are unknown.The purpose of the study was to analyze the effects of neuromuscular electrical stimulation (NMES) on muscle function, trophism and the Akt pathway signaling involved in muscular plasticity after incomplete-SCI in rats.This was an experimental study.Twenty-one adult female Wistar rats were divided into Sham, SCI, and SCI plus NMES groups. In injured animals, SCI-hemisection was induced by a surgical procedure at the C5-C7 level. The 5-weeks NMES protocol consisted in brachii biceps muscle stimulation, 5-times/week, initiated 48h after injury. Forepaw function and strength, biceps muscle trophism, and analysis of the phosphorylated Akt, p70S6K and GSK-3ß cellular anabolic pathway markers in stimulated muscle tissue were assessed.There was an increase in bicep muscle strength in the NMES group when compared with the untreated SCI group, from the 21st postoperative day until the end of the evaluation period (p<0.05). Also, there was an increase in muscle trophism in the NMES group when compared to the SCI group (p = 0.005). Forelimb function gradually recovered in both the SCI and NMES groups, with no differences between them. Regarding muscle protein expression, the NMES group had higher values for phospho-Akt (p = 0.047), phospho-p70S6K (p = 0.029) and phospho-GSK-3ß (p = 0.018) compared to the SCI group.These experimental findings were limited to an incomplete-SCI animal model and may not be fully generalizable to humans.Early cyclical-NMES therapy was shown to increase muscle strength and induce hypertrophy after incomplete-SCI in a rat model, probably by increasing phospho-Akt, phospho-p70S6K and phospho-GSK-3ß signaling protein synthesis.

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