Research On The Effect Of Vibration Therapy Based On Nerve Natural Frequency On Myelin Repair In SNI Model Rats

Background and Objective:In the process of nerve function repair after peripheral nerve injury（PNI）,vibration therapy plays a vital role,but its optimization parameters and mechanism of action are still unclear.Previous studies have shown that vibration therapy based on the natural frequency of the tissue can effectively improve the nerve function and myelin structure of PNI.In this study,a third-degree sciatic nerve injury model was prepared to observe the effect of vibration therapy with different amplitudes of natural frequencies on the recovery of sciatic nerve injury（SNI）rat nerve function,analyze the superior intervention parameters of vibration therapy,and further observe the activation of the signal pathways related to the proliferation of SCs and the expression of myelin proteins,and explore the potential mechanism of vibration therapy to promote the repair of damaged myelin.Method:Based on the natural frequency of the sciatic nerve,the adult SD rats were subjected to 21 consecutive days of local vibration treatment on the 7th day after modeling.（1）Observe the effects of vibration treatment with different amplitudes on the nerve function of experimental rats.The rats were randomly divided into five groups:Sham group,SNI group,SNI+1mm group,SNI+2mm group,SNI+4mm group,10 rats per group.The sciatic nerve function index（SFI）was measured at each time point.Tissues were collected on the 28th day after the operation to calculate the gastrocnemius wet weight ratio and the cross-sectional area（CSA）of??myocytes.The transmission electron microscope was used to measure the axon diameter and myelin thickness.Analyze the G ratio of axon myelination.（2）Observe the effects of vibration treatment with different amplitudes on the motor nerve conduction function of SNI model rats.The rats were randomly divided into five groups:Sham group,SNI group,SNI+1mm group,SNI+2mm group,SNI+4mm group,10 rats per group.On the 28th day after operation,the motor nerve conduction function of the injured sciatic nerve was detected,and the latency,amplitude and motor nerve conduction velocity（MNCV）of CMAP were recorded and analyzed.（3）Using molecular biotechnology to observe the expression of related proteins in SNI model rats by vibration therapy with different amplitudes.The first section detected the expression of S100,NGF,P75^NTRprotein in injured nerves and p-ERK1/2 protein in spinal cord tissue in the five groups of rats in the experiment（1）.In the second section,the rats were randomly divided into 4 groups:Sham group,SNI group,SNI+vibration group,SNI+U0126+vibration group,8 rats per group.On the 28th day after surgery,the effects of 2mm amplitude vibration treatment on SCs proliferation and MBP protein expression after administration of ERK1/2 pathway inhibitors were observed.Result:（1）Compared with the SNI model group,vibration therapy with 2mm and 4mm amplitude can increase the SFI level and gastrocnemius wet weight ratio in SNI rats,and vibration therapy with 1mm,2mm,and 4mm amplitude can effectively increase the gastrocnemius muscle cell CSA,2mm,4mm amplitude vibration group is better than1mm amplitude group;compared with SNI model group,2mm amplitude vibration treatment can increase the thickness of damaged myelin sheath and effectively reduce G ratio;1mm amplitude vibration group can effectively reduce G ratio,There is no difference in the thickness of the damaged myelin sheath.（2）Compared with the SNI model group,vibration treatment with 2mm amplitude can effectively shorten the latency of CMAP in SNI model rats;vibration treatment with1mm,2mm,4mm amplitude can effectively increase the amplitude of CAMP,2mm,4mm amplitude The positive effect of the vibration group is more significant;vibration treatment with 1mm and 2mm amplitude can effectively accelerate MNCV,but there is no difference between the SNI+A-4mm group and the SNI group.（3）Compared with the SNI model group,vibration treatment with 2mm and 4mm amplitude can up-regulate the expression of injured nerve S100,NGF protein and spinal cord p-ERK1/2.The 1mm amplitude group only shows the effect of promoting the expression of NGF protein.The up-regulation of P75^NTRprotein expression in the vibration treatment group was no different from that in the SNI group;compared with the SNI model group,vibration treatment with a 2mm amplitude increased the SFI level,promoted SCs proliferation,and MBP protein expression in SNI rats;compared with the SNI+U0126+vibration group,This positive effect was blocked by the ERK1/2 pathway inhibitor U0126.Conclusion:The vibration therapy based on the natural frequency of nerves can promote the recovery of nerve function in SNI model rats after surgery,delay the atrophy of gastrocnemius muscle,accelerate the repair of nerve myelin structure,and improve the motor nerve conduction function after SNI,and the vibration effect with 2mm amplitude is better.Vibration therapy with 2mm amplitude promotes the proliferation of SCs in the injured area,up-regulates the expression of NGF and MBP,and promotes the repair of damaged myelin,and this positive effect is related to the activation of the ERK1/2 signaling pathway.