Effects of Epidural Spinal Cord Stimulation and Treadmill Training on Locomotion Function and Ultrastructure of Spinal Cord Anterior Horn after Moderate Spinal Cord Injury in Rats

Objective:To investigate the effects of epidural spinal cord stimulation(ESCS) and treadmill training on the locomotion function and ultrastructure of spinal cord anterior horn after moderate spinal cord injury in rats.Method:Nine adult female Sprague-Dawley rats were randomly distributed into three groups:①spinal cord injury group(SI,n=3).②spinal cord injury plus ESCS group(SE,n=3).③spinal cord injury plus treadmill training group(TT,n=3).All rats received a moderate spinal cord injury surgery.Four weeks after surgery,rats in SE group received an electrode implantation procedure,with the electrode field covering spinal cord segments L2-S1.Four weeks after electrode implantation,rats received subthreshold ESCS for 30 min/d.Rats in TT group received 4cm/s treadmill training for 30min/d.Rats in SI group received no intervention,as a control group.All procedures in these three groups lasted four weeks.The open field Basso,Beattie and Bresnahan(BBB) scale was used before and after intervention to evaluate rats' hindlimb motor function.Result:After four weeks intervention,rats in TT group improved their open field locomotion scores to 20.In contrast,no significant improvement was observed in groups SI and SE.The morphology of synapses and neurons were similar regardless of whether rats had undergone ESCS,treadmill training or not.Conclusion:ESCS alone was not sufficient to improve the walking ability of spinal cord injured rats.ESCS or treadmill training alone might not contribute to the changes of ultrastructure in anterior horn of spinal cord that underlie the recovery of walking ability.Further research is needed to understand the contributions of combination of ESCS and treadmill training to the rehabilitation of spinal cord injured rats.