An Establishment And Evaluation Of A Rat Model With Delayed Paralysis After Ischemic Spinal Cord Injury

Objective To establish the rat model with delayed paralysis after ischemia spinal cord injury and observe the damage of spinal cord after ischemia-reperfusion, lay the foundation for further study of pathology and physiological mechanism,as well as spinal cord protection.Method The descending coronary artery ligation SD male rats to establish ISCI model.These SD male rats were randomly divided into two groups. The first group (room temperature37℃):sham group、9min group、10min group、11min group、11.5min group、12min group; the second group (low temperature32℃):sham group、18min group、21min group、24min group、27min group、30min group,33min group、35min、37min group.Observe the rat movement function of the hind legs and record the survival days. Select some rats in6h,12h,24h,36h,48h,3d and4d,5d,6d,7d after reperfusion to observe BBB behavior score. Make sure the best group that occur the delayed spinal cord injury,then take the spinal cord of the group rats in12h,24h,48h,72h after reperfusion for Nissl stain and immunohistochemical, and observe the change of glial cells in the light-microscopy.Statistical analysis:The SPSS17.0statistical software, measurement data of the experimental data as mean±standard deviation(x±s), many groups between material compares the single factor analysis of variance (ANOVA, one-way) and compares every two groups (LSD), the survival curves were compared using the log-rank test,with P<0.05difference have statistical significance.Results1.Motor function of hind legsAt11.5min group of room temperature,27%(n=4/15) rats appeared delayed motor dysfunction,.Increasing clamp time to12min,60%(n=9/15) began to appear immediate motor function obstacles. These groups that clamp time was less than llmin did not appear hind limb dysfunction.The21min group at32℃low temperature,14%(n=2/15) rats appeared delayed motor dysfunction, then the incidence gradually increased, the highest in35min, the incidence was74%(n=11/15).Increasing to37min, the rats began to appear instant paralysis, the incidence was67%(n=10/15).The rats does not appear to lmotor dysfunction in the sham group and18min group.2.Survival days7d survival rate of rats in each group after operation at room temperature is only21%, the majority died in the3d, and an increase in mortality increase with the clamp time (P<0.05), statistically significant,.The rate in low temperature group, the survival rate was78%in postoperative7d, and the survival rate of increase does not depend on the clamping time, P>0.05, not statistically significant.3.BBB scoreThe hind legs motor dysfunction almost appeared at24-36h after reperfusion in the low temperature, BBB behavioral score was6or0, the difference was statistically significant compared with the sham group.4.NISSL staining and immunohistochemicalIn the low temperature of32℃35min group,histopathology showed neurons degeneration and necrosis after24h of reperfusion,a large number of astrocytes and microglial expressed.The change was consistent with the hind limb motor dysfunction.Conclusion Clamping35min at32℃can establish a simple, reliable, repeatable, and high similarity delayed spinal cord injury rat model.