The Study Of Relationship Between Chronic Compressed Thoracic Spinal Cord Injury And Apoptosis

Objective:1.To establish an ideal and practical model of chronic compressed spinal cord injury in the rats, so as to provide a basis for further studies on pathophysiologic mechanism of chronic compressed spinal cord injury.2.To inspect the apoptosis of nerve cells in the rats under chronic compression by TUNEL,so as to investigate the significance of apoptosis in the chronic compression spinal cord injury.3.To detect the expression of TNF-R1 and Cyto-c in the spinal cord of rat under chronic compression, so as to investigate the mechanism of apoptosis in the chronic compression spinal cord injury.Methods:1. We had got forty adult healthy femal Wistar rats (250±20g,8-12weeks) which were been divided randomly into 2 groups which were chronic compression group(n=30), sham operation group(n=10).the chronic compression group were been divided randomly into 3 groups which were 3 weeks group(n=10),6weeks group (n=10),9 weeks group (n=10) 2. In the compression group,the lamina of vertebra of T9 was removed. A custom-designed compression device was implanted on the exposed spinal cord of female Wistar rat between the T8-T10 vertebral.A screw attached to a steel plate was tightened 1 pitch (0. 5mm)every 7 days for 3 weeks.The placement of device and the degree of compression were evaluated at 3 weeks by radiography of lateral projection of thoracic vertebrae..furthermore the motor function of Hindlimb was evaluate by BBB after 3,6,9weeks.Animals of sham operation group was only received the removment of lamina of vertebra.The motor function of Hindlimb was evaluated by BBB after 9weeks. Animals with acut spinal cord injury during the operation was eliminated。3.The spinal cord of T8-10 was harvested after BBB evaluation.10 rats each group,8 samples was embedded in paraffin before preparing 4 um transverse sections.2 samples was cut into 1mm transverse sections after 5 mins in-20℃freezer.The ice sections were stained with TTC to examine the ischemia of spinal cord. The paraffin section were stained with HE to examine the pathology of spinal cord. Furthermore,we used the paraffin section to detect apoptosis by TUNEL and the expression of TNF-R1 and Cyto-c by immunohistochemistry in the compressed spinal cord and the spinal cord of sham operation ratsresult:1.the palcement of compressive device was fine.The damage of spinal cord function was delitescence.compare with the sham operation group,The BBB score of rats in 3weeks'compression group did not reduced obviously,and the BBB score of rats in 6, 9 weeks'compression group reduced gradually. the difference of BBB score of rats during 3,6,9 weeks'compression group was significent(p<0.05) 2.The result of TTC indicate that foliated ischemia appeared at white matter of compressed spinal cord,especially the posterior column is evident.Neuron loss in grey matter and demyelination in white matter was found at compressed spinal cord stained with HE and pathological change aggratated with the extend of compression.3. TUNEL positive cell was found in WM and GM at compressed spinal cord. The number of these cells incread at 3W, reach to peak at 6W and reduced at 9 weeks in WM and GM.The difference of TUNEL positive cell was evident during 3,6,9W.4. The number of positive cell of TNF-Rland Cyto-c in the compressed spinal cord incread evidently compare to the control group.These posiyive cells reached to peak at 6 weeks.The former readued at 9weeks,but the later didn't.Conclusion:1.This self-designed device stimulate the clinical feature of chronic compressed spinal cord injury which have some virtues of convenient, simple, scientific, repetitive. This model is a convenient and practical for chronic compressed spinal cord injury.2.apoptosis play an important role to the nerve cell loss during the chronic compressed spinal cord injury whitch maybe happened in the whole process of spinal cord injury.3.The receptor path mediated by TNF-R1 and the mitochondria path mediated by Cyto-c take part in the apoptosis of never cell.We imagine that the latter play a leading function at advanced stage because of the high expression of Cyto-c positive cells in long time.