The Analgesic Effect And Mechanism Research Of Early High Frequency Spinal Cord Stimulation In The SNL Rat Model Of Neuropathic Pain

Introduction: Neuropathic pain is one kind of chronic pain,which is common in clinical practice and difficult to treat.Spinal cord stimulation has been used as the ultimate treatment for neuropathic pain.The mechanism of hyperalgesia in neuropathic pain is initiated at the early stage,which may be a cascade of reactions caused by nerve injury.Therefore,early standardized treatment of neuropathic pain and intervention in the mechanism of hyperalgesia are powerful measures to inhibit the development of neuropathic pain.High frequency spinal cord stimulation,as a new type of neural modulation technology,has removed the anesthesia of traditional Spinal cord stimulation and made its early application feasible.Spinal cord stimulation can change neurotransmitters and neurotransmitters according to several recent researches,but the mechanism of different frequency spinal cord stimulation,its relationship with the occurrence of neuropathic pain and the molecular biological mechanism associated with the development of neuropathic pain,is still unclear.Autophagy,one of the important mechanisms of maintaining cellular homeostasis,also changes in neuropathic pain.Recent studies have found that the late stage of autophagy is blocked in neuropathic pain,and when autophagy is activated by using rapamycin,an inhibitor of m TOR,leading to pain relief.Therefore,it is of great significance to study the specific mechanism of the blocked late stage of autophagy flux in neuropathic pain and to find ways to regulate the late stage of autophagy in neuropathic pain,which is of great significance to improve the therapeutic effect of neuropathic pain.Materials and Methods: The mechanical paw withdrawal threshold of sham group,SNL group,early high frequency stimulation group and early low frequency stimulation group were observed.The mechanical paw withdrawal threshold of sham group,SNL group,early high frequency stimulation treatment group,late high frequency stimulation treatment group were measured.By using chloroquine,autophagy marker LC3 and P62 in the spinal dorsal horn of sham group,SNL group,early high frequency stimulation group were estimated,to evaluate the changes of the autophagy flux in the spinal cord dorsal horn of each group.The protein expression of autophagy marker,LC3 and p62,the protein expression of LAMP2 and CTSD were compared in the sham group,SNL group,SNL plus early high-frequency stimulation group,which to evaluate the relationship among analgesic effect,autophagy flux influences,lysosomal function.With the help of PTEN inhibitor,bpv,we compared sham group with SNL group,and early high-frequency stimulation group,early high-frequency stimulation plus bpv group.Changes of protein expression of autophagy marker LC3 and P62 in the above groups were detected,the same as the protein expression of LAMP2,CTSD.To evaluate the relationship between the abirritation effect of early high-frequency spinal cord stimulation and PTEN-Akt-m TOR signal pathway,the mechanical paw withdrawal threshold and the protein expression of the PTEN-Akt-m TOR signaling pathway were checked.The karyoplasmic ratio of TFEB in each groups were also observed to present the cytoplasmic distribution of TFEB.In order to distinguish the certain type of nerval cells which early high frequency spinal cord stimulation may act mostly,we performed immunofluorescence co-localization technique.Results: When the simulator was turn off,the analgesic effect of early high frequency spinal cord stimulation was longer than that of early low frequency spinal cord stimulation.Early high frequency spinal cord stimulation had a better analgesic effect than the late high frequency spinal cord stimulation group.The LC3 Ⅱ of SNL group was increased significantly compared with that of the sham group,and was decreased by the early high frequency spinal cord stimulation.Early high frequency spinal cord electrical stimulation could reduce p62 in SNL rats.However,chloroquine,an advanced autophagy inhibitor,could greatly reduce analgesic effect of early high frequency spinal cord stimulation.In SNL group,LAMP2 and the matu-CTSD/pro-CTSD decreased and the ratio of TFEB(N)/TFEB(C)decreased.The early high frequency spinal cord electrical stimulation could alleviate the abnormal lysosome related parameters changes caused by SNL operation.After the application of bpv,the decrease of m TOR activity by early high frequency spinal cord stimulation was recovered.After inhibiting the PTEN-Akt-m TOR signal pathway of the spinal cord in the early high frequency spinal cord electrical stimulation group,its alleviation of the blocked autophagy flux induced by SNL,and the regulating effect of abnormal lysosome index was decreased.Moreover,the analgesic effect of the early high-frequency electrical stimulation of spinal cord was significantly weakened after the cessation of the stimulation.The immunofluorescence results revealed that the autophagy regulation effect of early high frequency spinal cord stimulation was mostly taken place in the neurons of the superficial layers in the spinal dorsal horn of SNL rats..Conclusions:1.Early application of high frequency spinal cord stimulation has better analgesic effect.2.Early high frequency stimulation of the spinal cord can relieve neuropathic pain in SNL rat by relieving the blockage of the autophagy flux in superficial neurons of the spinal cord dorsal horn.3.The analgesic effect of early high-frequency spinal cord stimulation was related to its regulation of the PTEN-Akt-m TOR signal pathway and TFEB karyoplasmic distribution which promoting the lysosomal function in the spinal cord horn of SNL rat.