Superphosphorylation Of Tau Protein In Neuronal Retrograde Degeneration After Brachial Plexus Injury

[Objective]:Brachial plexus root avulsion injury is a kind of serious peripheral nerve injury,which can cause severe impairment of upper limb function.The contralateral cervical 7 nerve transfer surgery brings hope to those patients.In order to further improve the curative effect of operation,a difficult problem to overcome is the neuronal retrograde degeneration(NRD)of spinal cord caused by cutting the cervical 7 nerve.Abnormal phosphorylation of Tau protein occurs in many degenerative diseases of central nervous system,but whether there is superphosphorylation of Tau protein in the process of retrograde degeneration of central nervous system after peripheral nerve injury has not been reported.The purpose of this study is to investigate the changes of superphosphorylation modification of Tau protein in this degeneration process.[Methods]:The model of cervical 7 neurotomy in SD rats was created,and the spinal cord tissues of the 7 segments of the rat cervical spinal cord were obtained after feeding for 2,4,6 and 8 weeks.The apoptotic status of nerve cells and the phosphorylation level of Tau protein were analyzed by HE staining,flow cytometry,Western Blot and immunohistochemistry.Lithium chloride was given in an attempt to block the intermediate process of neuronal apoptosis.The apoptotic status and phosphorylation level of Tau protein of the nerve cells after treatment were compared.[Results]:HE staining and flow cytometry showed that the apoptotic degree at 2 weeks was less than that at 4 weeks.Western Blot and immunohistochemical results showed that with the increase of weeks,the total amount of Tau protein decreased due to the severance of cervical 7 nerve,and the proportion of phosphorylated Tau protein increased.After lithium chloride was given,the apoptotic degree and the proportion of phosphorylated Tau protein decreased.[Conclusion]:Superphosphorylation of Tau protein occurs during the neuronal retrograde degeneration of spinal cord after cervical 7 neurotomy,and lithium chloride can alleviate the degree of retrograde degeneration.