Melatonin And Chondroitinase ABC Effectively Promote Nerve Regeneration And Functional Recovery In Rats With Root Avulsion Brachial Plexus Injury

Background:Brachial plexus root avulsion type damage(BPA)is also known as "longitudinal spinal cord damage",is a common,ending the worst forms of brachial plexus injury,traffic accident or pull violent cause in the process of production is located in the "transition zone" of spinal nerve root fracture separation,starting from the spinal cord caused by continuous or intermittent neuralgia patients with corresponding area and autonomic nerve dysfunction,upper limb feel barriers,the lack of movement function.Root avulsion brachial plexus injury involves both peripheral and central nerves,which is difficult and ineffective in clinical treatment.Currently,the most popular clinical treatment methods include nerve transposition and functional reconstruction,etc.,which are not effective and may cause a variety of side effects.In recent years,many scholars have attempted to treat brachial plexus nerve root avulsion by reinserting the avulsed nerve roots in situ through nerve replantation,and some results have been achieved.After the injury,the upper limb function can be recovered to a certain extent,and the side injuries caused by the traditional treatment such as nerve displacement and functional reconstruction can be avoided.Type root avulsion injury of brachial plexus injury degree and mechanism of complex is mainly due to the original injury caused directly border area disappear synaptic connections,axonal injury,demyelination,motor neurons of death at the same time,further inflammation,oxidative stress,blood spinal cord barrier damage and glial scar formation of secondary reaction,cause damage area expands unceasingly.It affects neuron survival,axon regeneration and neuromuscular synapse formation,and restricts nerve function recovery.Oxidative injury and inflammatory response are important early pathological changes of nerve injury,which can cause a large number of neuron deaths,and are important therapeutic targets for nerve regeneration.After primary mechanical injury,a large number of ROS produced by secondary reactions interact with lipids,nucleic acids and proteins to cause cell damage and even apoptosis.A large number ofinflammatory cells are gathered at the injury site,and inflammatory mediators such as IL-6 and IL-1 are released,which initiates apoptosis and aggravated tissue edema,resulting in a large number of neuron deaths and deterioration of neural function.The formation of local scar tissue and the secretion of a large number of inhibitory molecules hinder axon regeneration and extraverted extension.The destruction of a large number of neurons in the early stage of injury and various hindrance factors in the process of nerve regeneration make the peripheral nerves unable to establish the continuity with the central part quickly and effectively,resulting in the missed recovery time of the effect muscle atrophy,and thus the treatment effect is not good.Among a large number of factors that inhibit nerve regeneration after central nervous injury,early oxidation and inflammatory injury are important factors that continuously reduce the number of neurons,while glial scar and chondroitin sulfate proteoglycan are the main physical and chemical barriers of late axonal regeneration and extension.After brachial plexus nerve root avulsion injury,glial scar is widely existed in the central nervous system and peripheral nerve outer membrane,and it has an inhibitory effect on axon regeneration throughout the process.Materials and methods: For inflammatory reactions and oxidative damage,this study used melatonin for treatment,which can remove free radicals,regulate the expression of endogenous antioxidant enzymes,and has anti-inflammatory,antioxidant and neuroprotective effects.For the glial scar and its main component chondroitin sulfate proteoglycan,the current main treatment plan is to use chondroitinase to digest the glycosaminoglycan chain on the chondroitin sulfate proteoglycan.In this study,MT has anti-inflammatory and antioxidant effects in different pathological stages,which can reduce the destruction and death of neurons in the acute stage and has neuroprotective functions.Ch ABC can dissolve CSPGs,reduce the formation of chronic glial scar,and promote axon regeneration and extension.In this study,adult female SD rats were used as experimental animals,and microsurgery was performed through the posterior cervical and thoracic vertebrae to establish a right rhizotic brachial plexus injury model and replantation model.During the operation,the posterior spinal nerve root of c5-c7 was incisively cut,and the anterior spinal nerve root of C5-C7 was avulsed.Then,partial anterior spinal nerveroots of C5 and C7 were removed to avoid regeneration,and the anterior spinal nerve root of C6 was retransplanted to the corresponding intervertebral foramen.The 52 rats were randomly divided into four groups(N=13)and treated as follows: the control group was given intraperitoneal injection of 5% alcohol saline(5 minutes and 1,2,3,4 hours after surgery),and the gelatin sponge was absorbed with 10 l saline to cover the C6 nerve roots after replantation.In the MT treatment group,5% alcohol saline was intraperitoneally injected(5 min after surgery and 1,2,3,4 hours after surgery),and 10μl saline was absorbed from the gelatin sponge to cover the C6 nerve roots after replantation.In the Ch ABC treatment group,5% alcohol saline was intraperitoneally injected(5 minutes and 1,2,3,4 hours after surgery),and 10 μl Ch ABC(2.5U/ml)saline solution was absorbed from the gelatin sponge to cover the C6 nerve roots after replantation.The combined treatment group was given intraperitoneal injection of 5% alcohol saline(5 minutes and 1,2,3,4 h after surgery),and the gelatin sponge was soaked with 10μl Ch ABC(2.5U/ml)saline solution to cover the replanted C6 nerve roots.Results:The levels of MPO and MDA in the spinal cord were measured by spectrophotometry 24 hours after injury,and the levels of inflammation and oxidative damage were evaluated.The survival rate of C6 anterior horn neurons in the spinal cord specimens of the injured side was detected by microinjection of fluorescent gold retrograde labeled neurons into the myodermal nerve fibers and immunofluorescence staining with choline acetyltransferase.The content of glial scar in the spinal cord specimens of the injured segment was determined by immunofluorescence staining with glial fiber acidic protein,and changes in the central end were evaluated.After 2-6 weeks of operation,the upper limb function of rats was evaluated by TGT(once a week),and neuro-electrophysiological examination of musculocutaneous nerve-biceps humerus was performed 6 weeks after operation.The motor endplate in biceps humerus was marked by-btx,the number and morphology of the motor endplate were observed,and the changes of the motor system effector organs in each group were compared.Combined with the results of the above evaluation indexes,the effects of simple replantation,Ch ABC treatment,MT treatment and combination of Ch ABC+MT treatment on neurons,peripheral nerves,innervated muscles and motor functions after replantation of avulsed brachial plexus nerve roots were evaluated andcompared.After the analysis of the experimental results,we had come to the following conclusions:1.Nerve root replantation after brachial plexus nerve root avulsion can restore nerve function to a certain extent.2.The application of Ch ABC after nerve root replantation of brachial plexus nerve root avulsion injury can reduce the formation of glial scar,promote axon regeneration and restore nerve function after nerve replantation of brachial plexus nerve root avulsion injury.3.Melatonin has a definite protective effect on the survival of nerve after brachial plexus nerve root avulsion replantation,which can effectively reduce the early inflammatory reaction and oxidative damage,and promote the recovery of nerve function after nerve replantation of brachial plexus nerve injury caused by root avulsion.4.Ch ABC combined with melatonin can more effectively promote nerve regeneration and functional recovery after brachial plexus nerve root avulsion replantation.Conclusion:To sum up,this experimental study found that nerve function can also be partially restored after nerve root replantation of root avulsion brachial plexus injury without drug intervention.The indexes of inflammation and oxidative damage were increased in the early stage of nerve injury.Effective anti-inflammatory and antioxidant therapy can increase the survival of neurons in the early stage and obtain good recovery effect of motor nerve function in the later stage.After the root avulsion brachial plexus injury,the glial scar around the spinal cord increases greatly,which is an important physical and chemical barrier after nerve injury.Combined application of MT and Ch ABC to select oxidative injury,inflammatory reaction and glial scar formation as therapeutic targets for nerve injury can provide whole-process protection for nerve regeneration in the acute and chronic stages of injury.In addition to reducing the damage of oxidative injury and inflammatory injury to neurons,it can also reduce the formation of glial scar,promote axon regeneration and the recovery of nerve function after root avulsion type BPI.The study on the relative curative effect and application of Ch ABC and MT provided experimental basis for improving thefunctional recovery after nerve replantation in brachial plexus nerve root avulsion injury.