| Objective:To establish the model of rat spinal cord hemisection,which will be applacated for further studies about complex physiologic and histo-pathologic changes after spinal cord injury.To study the effect of chondroitinase ABC(ChABC) on the restore of function for spinal cord injury.To find the therapeutic time window for the application of chondroitinase ABC after spinal cord injury.Methods:1.150 adult male Wistar rats were randomly divided into 6 groups(n=25),and the model of rat spinal cord hemisection was performed.The control group does not be treatmented after injury.The rats of treated groups were administrated with chondroitinase at the time of injured immediately,1d,3d,7d and 14d post-operatively.The animals received ChABC treatment by intraventricular injection.2.Use the BBB scale to value the rats' behavial changes regularly before and after injury and observe the functional recovery of rat spinal cord for 3 months.3 rats were killed randomly in every group in 1w,2w,4w,8w after injury.Spinal sections were processed for HE staining,GFAP and NG2 immunostaining.Western blot detections of spinal cord after injury were performed to observe glial scar tissue and the morphological changes CSPGs expression level.Results:1.The rat spinal cord hemisection model is successful and stable,it shows as a typical BrownSequard syndrome,and the wound is clean,the modle is reproducible and the injury grade is constant,the anatomical location is accurate, the dysfunction is also confirmed.In a word,this modle is suitable for the basic research on spinal cord injury and for the neurobiological research.2.The BBB scores of rats in each group were 0～1 points within the first 3 days. There were no statistical significance among all the groups(P＞0.05).The BBB scores then gradually increased with the time going on,and show that the neurological function recovered fastly in 1～8 weeks after injury,the differences of BBB score among these groups are significant,the immediately treated group,1d treated group,3d treated group,7d treated group are better than the control group, the difference between the early treated groups and the control group is significant (P＜0.05),but the 14d treated group has no obvious difference compared with the control group(P＞0.05).After 12 weeks the immediately treated group,1d treated group,3d treated group,7d treated group are better recovered than the control group,the difference was significant(P＜0.05).There was no statistical significance between the 14d treated group and the control group(P＞0.05).3.The HE staining sections of the control group showed a large number of glial cells hyperplasia and the formation of glial scar after injury.The glial scar in the treated groups were less than the control group.Immunohistochemistry showed that the expression of GFAP in all the animals of injured groups increased than no injured animals,but there was no statistical significance among all of these groups (P＞0.05).This indicates that ChABC has no direct effect on astrocytes cells.4.NG2 immunohistochemistry and Western blot indicated:CSPGs expression levels increased and reached the peak 2 weeks after injury.CSPGs expression levels of the immediately treated group,1d treated group,3d treated group,7d treated group were significantly lower than the control group(P＜0.05).There was no obvious difference between 14d treated group and the control group(P＞0.05).4 weeks later,The levels of the immediately group,1d treated group,3d treated group,7d treated group were significantly lower than the control group(P＜0.05). 14d treated group had no obvious difference compared with the control group(P＞0.05).8 weeks after injury CSPGs expression levels of the immediately treated group,1d treated group,3d treated group and 7d treated group were significantly lower compared with the control group(P＜0.05),while 14d treated group had no obvious difference compared with the control group(P＞0.05).Conclusions:1.The rat spinal cord hemisection model is successful and stable,and the wound is clean,the modle is reproducible and the injury grade is constant,the anatomical location is accurate,the dysfunction is also confirmed.In a word,this modle is suitable for the basic research on spinal cord injury and for the neurobiological research.2.ChABC can promote the motor function recovery after spinal cord injury, treatment with ChABC after spinal cord injury inhibits glial scar formation and has beneficial effects on the repair of neural cells.3.The therapeutic effect of ChABC was dependent on the timing of the administration,it is best to applicate immedietly after injury and has good effect within 1 week.There is no effect on the rats which injured more than 1 week.
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