Electromagnetic field stimulation facilitates motor neuron excitability, myogenesis and muscle contractility in spinal cord transected rats.

Spinal cord injury (SCI) is one of the most devastating injuries which causes either complete or partial loss of movement, balance, muscular coordination and endurance. Electromagnetic field (EMF) stimulation has been shown to reduce muscle atrophy and fiber-type switching and improves muscle function in a hindlimb suspension model. The present study aims to elucidate the therapeutic potential of EMF stimulation on motor neuron excitability, soleus muscle morphology and function in complete SCI rats. Thirty-six adult male Wistar rats were randomly divided into Sham, SCI and SCI+EMF groups. Complete transection was done at the T13 spinal level, followed by whole-body EMF exposure for 7 or 14 days. Hyper-reflexia, muscle atrophy, reduction in twitch and tetanic force with earlier onset of fatigue was evident in the SCI group. EMF stimulation showed significant improvement in H and M wave parameters, H/M ratio, muscle twitch and tetanic force, fusion frequency and fatigability. A significant increase in regenerating myofibers and reduction in muscle degeneration following EMF was evident on histopathological examination. Further, EMF significantly increased myogenic protein levels responsible for muscle regeneration. Our study demonstrates for the first time the potential of EMF to modulate motor neuron excitability and muscle contractile function in SCI rats through activity-dependent mechanisms.