Changes Of GAP43 And S100B In Different Repair Methods After Sciatic Nerve Injury In Rats

Nerve regeneration and functional recovery are the focus of peripheral neuroscience research after peripheral nerve injury.At present,the commonly used methods of repairing peripheral nerve injury include end-to-end anastomosis,autologous nerve graft and artificial nerve,but surgical techniques are difficult to further improve the precision of motor nerve repair.Therefore,it is of great significance to fully understand the cellular characteristics and molecular regulation in the process of peripheral nerve regeneration for functional repair after nerve injury.Schwann cells are unique glial cells in the peripheral nervous system.After peripheral nerve injury,Schwann cells proliferate,migrate in large numbers and secrete nutrient factors and other mechanisms to promote the repair of peripheral nerve injury.S100 B is specifical maker for Schwann cells in peripheral nerves.GAP43 is a specific growth-associated protein of nerve tissue,which is produced in the axon of development or regeneration and transported to the growth cone.GAP43 is needed to promote the extension and reconstruction of the axon after nerve injury.In this study,we examined the expression of GAP43 and S100 B in embryonic and primary cultured sciatic nerve cells in vitro for exploring the expression patterns of GAP43 and S100 B in differentiation and proliferation of Schwann cells.Anastomosis,autologous nerve graft and artificial nerve were used to investigate the relationship between GAP43 and S100 B synergistic changes and different repair effects in the repair methods of peripheral nerve injury.It is helpful to understand the molecular mechanism of gene regulation in nerve regeneration and repair of nerve function,meanwhile it has important guiding significance for clinical repair of peripheral nerve injury.The results showed that:1.The expression and distribution of GAP43 and S100 B in the rat embryonic neural plate-spinal development stage were detected.It was found that GAP43 and S100 B were co-localized in the peri-spinal cells of the 18 th day embryonic stage.2.In the primary sciatic nerve from nerve source cultured in vitro,the cell morphology was typical bipolar slender spindle-shaped,and the cell aggregation and arrangement was regular,which was Schwann cells.At the 7th day of primary culture,cell proliferation was obvious,and co-localization of GAP43 and S100 B fluorescence signals was detected.3.Immunofluorescence analysis:(1)In the proximal nerve,the level of GAP43 protein increased at first and then decreased.At the 14 th day after operation,the level of GAP43 protein reached the peak in the end-to-end anastomosis group and autologous nerve graft group,while in the nerve tube group,the peak time was delayed to the 21 th day.In the distal nerve,the GAP43 protein level reached the peak at the 21 th day in the end-to-end anastomosis group and the autologous nerve graft group,while the GAP43 protein level in the nerve tube group continued to rise to the 30 th day and was higher than that in other experimental groups(p < 0.05).(2)In the proximal nerve,the level of S100 B protein in each experimental group decreased at the early stage of nerve repair,and that in the nerve tube group decreased significantly compared with the other two experimental groups(p < 0.05).At the 7th day,the level of S100 B protein in nerve tube group decreased to the trough bottom,while that in end-to-end anastomosis group and autologous nerve graft group decreased relatively slowly.The lowest level of S100 B protein was postponed to the 14 th day in anastomosis and autologous nerve graft group.The level of S100 B protein in each experimental group increased on the 21 th day after operation.In the distal nerve,the level of S100 B protein in each experimental group decreased sharply at the 3rd day,and the level of S100 B protein in each experimental group picked up to the level of control group at the 21 th day after operation.4.The results of gene expression showed that: within 14 th day,the expression of Gap43 mRNA in each experimental group showed an upward trend.The expression of Gap43 mRNA in end-to-end anastomosis and autologous nerve graft reached the peak,while continued to rise in nerve tube.From 21 th day to 30 th day days,the expression of Gap43 gene decreased gradually in end-to-end anastomosis and autologous nerve graft group,while increased continuously in nerve tube group,and was higher than that in other two experimental groups(p < 0.05).The expression of S100 b mRNA was similar to protein expression in the experimental groups.At the 3rd day,the expression of S100 b decreased sharply,and recovered steadily at the 7th day.The expression of S100 b reached its peak from the 7th to 14 th day in the end-to-end anastomosis and the autologous nerve graft group,while the peak expression of S100 b in the nerve tube group was postponed to only the 21 st day after operation.5.The morphological observation,HE staining and axon NF200 immunofluorescence detection,sensory function test and gastrocnemius wet weight rate test were used to evaluate the repair of peripheral nerve injury effect.The morphological and structural recovery of the nerve tissue in the end-to-end anastomosis group and the autologous nerve graft group was better than that in the nerve tube group,which echoed the peak of GAP43 and S100 B mRNA and protein levels earlier than the nerve tube group.In summary,the experimental results show that in the early repair stage of peripheral nerve injury,the synergistic expression of Schwann cells GAP43 and S100 B is regulated from the gene level,which is beneficial to promote nerve repair process and improve postoperative repair effect.