成年新西兰白兔144只，随机平均分为6组：A组（阴性对照组）、B组（缺血再灌注组）、C组（小剂量MP组）、D组（Vc组）、E（大剂量MP组）、F组（MP+Vc组）。夹闭腹主动脉25 min后移除动脉夹造成缺血再灌注模型，随即给予相应的处理。于再灌注30 min、6、12、24、48 h每组各取4只动物，检测丙二醛MDA、过氧化氢酶CAT、超氧化物歧化酶SOD、谷胱甘肽过氧物酶GSH-Px表达水平；每组取4只动物于麻醉清醒即刻、再灌注24、48 h按Tarlov 评分系统行后肢运动功能评分，并于48 h评分完毕后取材行HE染色及TUNEL凋亡染色。
第一部分：A、E、F组MDA、CAT、SOD、GSH-Px于再灌注30 min、6、12、24 h表达水平明显低于B、C、D组，且A、E、F 3组间无明显差异；Tarlov 评分结果提示E（3.25±0.43）、F（3.50±0.50）组明显优于B（2.00±0.71）、C（2.50±0.50）、D（2.50±0.50）组；HE染色及TUNEL凋亡染色观察E组（29.68±4.57）%与F组（30.50±4.40）%损伤程度及细胞凋亡指数相当，均明显低于其他组。
Ischemia/Reperfusion after Spinal Cord Injury
Candidate for master: Liu Zhiheng
Supervisor: Luo Zhuojing
Department of Orthopaedics, Xijing hospital, Fourth Military Medical University,
Xi’an 710032, China
spinal cord injury has a high incidence, resulting in serious consequences, not only bring physical and psychological problems, but also bring many family and society problems. The mechanism and the process of spinal cord injury has been gradually revealed, and the development of drug treatment has achieved some success, but we still need some effective and inexpensive drugs.
A number of mechanisms happened in spinal cord injury and ischemia/reperfusion injury is particularly concerned. I/R injury plays an important role both in the spinal cord injury and other iatrogenic injuries. MP and GM-1 were recommended as a treatment after spinal cord injury, but their application in clinical often bring many potential complications. According to the pharmacological characteristics and economic costs of MP, combined with extensive effect of vitamin C in the body, the co-application may be a good choice, and to avoid potential complications. And some patients (1.5% -3%) can occur with unexplained loss of spinal function after received spinal decompression surgery, some researchers hold the opinion that it was caused by I/R injury happened in decompression tissue. Compare the efficacy of MP alone with co-application of vitamin C combined with MP, investigate I/R injury after decompression of chronic spinal cord compression, discuss the injury mechanism.
1 To investigate the protection of co-application of low dose MP and ascorbic acid in I/R model.
2 To investigate I/R injury after spinal cord decompression.
Part 1 The protection of co-application MP and ascorbic acid in acute spinal cord I/R injury model
Spinal cord ischemia model was induced by clamping the infrarenal aortic for 25 min. 144 New Zealand white rabbits were randomized as follows: A(negative control group)、B（I/R group）、C(low-dose MP)、D（Vc）、E（high-dose MP group）、F（MP+Vc）.Each group was given the corresponding disposal. The neurological score、MDA、SOD、CAT、GDH-Px levels were detected at different time point；H&E and Tunel stains were observed at 48h.
Part 2 Ischemia / reperfusion injury after decompression in chronic spinal cord compression
96 New Zealand white rabbits were randomized as follows: A (negative control group), B（I/R group), C（Decompression group). MDA、SOD、CAT、GDH-Px were detected at 0h, 30min, 6h, 12h, 24h, 48h. Apoptosis cell numbers were analysis at 0h and 48h.
MDA、SOD、CAT、GDH-Px levels in groupA、E、F at different time were significantly decreased. but there were no significant difference among group A、E、F；Tarlov scores of group E、F show significantly increase compared with group C and D；And H&E and Tunel stains show group E and F have the similar injury extent during I/R compared with group B、C and D.
MDA、SOD、CAT and GSH-Px levels in group B were significantly increased compared with group A at 30min, 6h, 12h, 24h, the levels in Group C were significantly increased compared with group A at each time point, and there were no difference in group C; Tunel stain shows the apoptosis cell number has no significant difference between 0h and 48h in group C.
1 The co-application of low dose MP and ascorbic acid shows the same therapeutic effect to spinal cord ischemia-reperfusion compared with large dose MP.
2 There were no significant I/R injury after spinal cord decompression, I/R injury was not the cause of disfunction after spinal cord decompression.
Key words：Spinal cord injury; Ischemia-reperfusion; Methylprednisolone;
ascorbic acid; chronic compression