Microelectrode Stimulation Study On Brain Plasticity After Defecation Reconstruction Following Spinal Cord Injury

Objectives: Establishing nerve roots transplant animal model with mechanical polishing method,positioning brain center of defecation function by multiple methods and using microelectrode stimulation to monitor brain plasticity after defecation reconstruction via neural approaches in rats with spinal cord injury.Methods: Adult female SD rats were selected.The animal model,which built by bilateral anastomosis of L5 root and S1 root though mechanical polishing method,were used to reconstruct defecation,and then monitored it validity by morphology and function ways.The most efficient brain center innervating defecation were identified by functional magnetic resonance imaging(f MRI),PRV nerve retrograde tracing and microelectrode stimulation.Microelectrode stimulation was performed to normal rats as control group and 3 groups' rats 1 month,6 months and 12 months after the operation,and then observed the process of brain plasticity changes though brain mapping.Results: Mechanical polishing method have shorter operative time,less blood loss and lower postoperative mortality than traditional method.The retrograde tracer PRV detected the positive green fluorescent expression in the proximal end of the anastomosis,Toluidine blue and electron microscopy showed that there was regenerated nerve fiber at the anastomosis and electrophysiological examination of the anorectal rectum shows that the anal canal pressure of model rats can be restored to normal rats L5 and S1 levels.Thus,it is feasible and effective to reconstruct the defecation function of spinal cord injury by bilateral anastomosis of L5 dorsal and ventral root with S1 dorsal and ventral root.Periaqueductal gray and Barrington's nucleus plays a major role in defecation function and regulate it with multinuclear groups,such as the thalamus,midbrain and cerebral cortex in rats.Microelectrode stimulation showed obvious defecation central inhibition in 1 mouth after operation,and partial re-domination of defecation function in 6 months after operation.In the 12 months after the operation,the corresponding area in the brain of the model rat turned from inhibition to de-inhibition.Conclusions: Nerve root transplants provide the feasibility of reconstitution of defecation after spinal cord injury.Brain areas can re-dominate defecation function through brain plasticity.The experiment results can provide feasible method for patients with spinal cord injury to achieve voluntary defecation.