| Background And Purpose: Spinal cord injury(SCI)is one of the main challenges in neurotrauma research.A complex pathophysiological process occurs after spinal cord injury,leading to axon rupture,demyelinating changes,and loss of nerve function.These changes will worsen with the development of chronic injury.Low frequency pulsed electromagnetic field(LFPEMF)is a new type of electrophysiological technology.Our previous research has proved that LFPEMF can promote oligodendrocyte differentiation and promote myelin regeneration.It has neuroprotective and nutritional effects,Can ultimately promote the recovery of neural function after spinal cord injury.Based on this,this subject further explores the effects of low-frequency pulsed electromagnetic fields on axon regeneration after SCI and its possible molecular mechanisms,and provides theoretical basis and treatment strategies for the treatment of spinal cord injury.Methods: The SD rat SCI model was constructed using Allen's blow method,and then SD rats were randomly divided into three groups: a sham operation group,a spinal cord injury group,and a magnetic field treatment group.In the magnetic field treatment group,continuous magnetic field stimulation was performed for 4 hours at 8 am to 12 pm daily after surgery.The BBB score of rat motor function was measured from 1 week to 8 weeks after operation to evaluate the motor function of hind limbs after SCI,and it was evaluated once a week.Tissue immunofluorescence staining was used to detect NeuN positive cells at 7 days after operation to evaluate the Rat SCI mature nerve cell regeneration;Western blot and tissue immunofluorescence staining were used to detect GAP-43 and NF200 at 7 days after operation to evaluate axon regeneration in rat SCI;Western blot was used to detect whether LFPEMF treatment can promote CREB and STAT3 phosphorylation and promote axonal growth after SCI in rats 7 days after surgery;Western blot was used to detect tumor necrosis factor-?(TNF-?)and interleukin-6(IL-6)at 7 and 14 days after operation to evaluate the expression of inflammatory factors in rats;Western blot was used to detect the expression of PTEN,Western blot was used to detect the expression of GSK-3?,Akt,mTOR phosphorylation,tissue immunofluorescence staining was used to detect the localization and expression of GSK-3?,and the PI3 K / Akt / mTOR signaling pathway was detected by LFPEMF treatment and axon regeneration Expression in each group.We follow the "random" and "blind" methods for the establishment of experimental rat injury models,experimental grouping,and related experimental data collection and analysis.Results:(1)The results of BBB motor function scores of SD rats showed that: in the sham operation group,the BBB motor function scores of rats were not significantly different at the weekly detection time points of 1-8 weeks after operation(P> 0.05).Compared with the spinal cord injury group,the average BBB score was not significantly different in the first week after surgery(P> 0.05),but the monitoring time at 2-8 weeks was significantly longer than the latter,and the difference was statistically significant(P <0.01);(2)Tissue immunofluorescence staining of neurons in the injured spinal cord of rats in each group at 7 days postoperatively using Neu N antibody showed that the number of mature neurons in the magnetic field treatment group was significantly increased compared with the spinal cord injury group,the difference is statistically significant(<0.01);(3)Western blot and tissue immunofluorescence staining of the magnetic field of the spinal cord injury group and the treatment group using GAP43 and NF200 antibodies showed that the axon regeneration of the rats in the magnetic field treatment group was significantly higher than that of the spinal cord injury group at 7 days after surgery.Statistically significant(P <0.05);(4)The Western blot results of CREB and STAT3 antibodies showed that the protein phosphorylation level of rats in the magnetic field treatment group was significantly increased at 7 days after operation,indicating that LFPEMF can promote the growth of neurites,and the difference was statistically significant(P <0.05);(5)Western blot results showed that at 7 and 14 days after surgery,the expression levels of inflammatory factors interleukin-6(IL-6)and tumor necrosis factor-?(TNF-?)in the spinal cord tissue of the magnetic field treated rats were compared with spinal cord injury.All the groups were significantly reduced,and the difference was statistically significant(P <0.05).(6)At 14 days after operation,compared with the spinal cord injury group,the expression level of PTEN in the spinal cord tissue of the rats in the magnetic field treatment group was reduced,and the levels of AKT and mTOR phosphorylation in the downstream PI3K/Akt/mTOR signaling pathway were significantly increased,which promoted axonal growth GSK-3? inhibits axon regeneration,p-GSK-3? increases after magnetic field treatment,which is beneficial to axon regeneration,and the expression difference is statistically significant(P <0.05).Conclusions: LFPEMF can promote the inactivation of GSK-3? phosphorylation by down-regulating PTEN levels and activation of the downstream PI3K/Akt/mTOR signaling pathway.It can also promote CREB and STAT3 phosphorylation levels,thereby promoting neuron survival and axonal growth.Inhibit the role of inflammatory factors in the microenvironment,and finally promote spinal axon regeneration and nerve function recovery in rats after SCI. |
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