肢体远程预处理通过上调机体抗氧化酶活性诱导兔脊髓缺血耐受

目的:证实抗氧化酶活性上调是肢体远程预处理(remote preconditioning,RPC)诱导兔脊髓缺血耐受效应的主要机制之一。方法:60只雄性新西兰大白兔随机分成对照组、远程预处理组、缺血组及RPC 缺血组(对照组n=6,余组n=18)。RPC组行双下肢短暂缺血2次(每次10min,间隔10min);缺血组仅行脊髓缺血模型;RPC 缺血组在远程预处理后1h行脊髓缺血;对照组为假手术组。对照组于脊髓缺血再灌注后48h行神经功能评分后取脊髓,作为对照。余三组分别于再灌注后6h、24h及48h评分后取材,各时间点各取6只。所有动物于缺血前、缺血20min、再灌注20min及再灌注6h采动脉血测血清抗氧化酶活性和丙二醛(MDA)含量;于取材后测定脊髓匀浆抗氧化酶活性和MDA含量。结果:再灌注后6h、24h及48h时对照组、远程预处理组及远程预处理 缺血组神经功能评分均明显高于缺血组(P<0.05)。血浆超氧化物歧化酶(SOD)活性和过氧化氢酶(CAT)活性在每个时间点RPC组均高于对照组,RPC 缺血组高于缺血组(P<0.05);其中缺血20min时,缺血组血浆SOD、CAT活性低于对照组,RPC 缺血组低于RPC组(P<0.05);而与缺血前相比,缺血20min时缺血组及RPC 缺血组SOD和CAT活性显著下降(P<0.05)再灌注24h和48h时,脊髓匀浆SOD、CAT活性对照组低于RPC组,缺血组低于RPC 缺血组(P<0.01);而MDA含量再灌注24h时对照组高于RPC组,缺血组高于RPC 缺血组(P<0.05)。脊髓匀浆SOD、CAT活性与神经功能评分具有显著相关性。结论:RPC诱导脊髓缺血耐受的机制可能为上调抗氧化酶活性,增强机体在缺血再灌注过程中清除氧自由基的能力,从而减少氧自由基介导的损伤,发挥脊髓保护作用。

Limb Remote Ischemic Preconditioning Induces Tolerance Against Spinal Cord Ischemia by Upregulation of Antioxidant Enzymes Activities in Rabbits

Objective:To examine the hypothesis that spinal cord ischemic tolerance induced by limb remote preconditioning(RPC)is mediated by an increase of andoxidant enzyme activities.Methods:Sixty male adult New Zealand white rabbits were randomly divided into four groups:control group,RPC group,ischemia group and RPC ischemia group (6 in control group,18 in other three groups).The animals in RPC group underwent two cycles of 10min hind-limb ischemia;and the animals in ischemia group underwent infrarenal aorta occlusion for 20min.Control group is the sham group,animals in which were neurologically assessed at 48h after reperfusion and then sacrificed.Other three groups were respectively divided into three subgroups according to the time of reperfusion (6h,24h,48h).Each subgroup has six animals and the animals were sacrificed after neurological assessmem.Arterial blood was sampled at pre-ischemia,20rain post-ischemia,reperfusion 20min and reperfusion 6h in each group for the determination of andoxidant enzyme activities and MDA content.Spinal cords L5-7 were also sampled for detecting antioxidant enzyme activities and MDA content.Results:The neurological outcomes in control,RPC and RPG ischemia groups were better than that in ischemia group at 6h,24h and 48h after reperfusion (P<0.05).At each time point,serum activities of SOD and CAT in RPC group were higher than that in the control group;while RPC ischemia group higher than ischemia group.At 20min after ischemia,serum activities of SOD and CAT in ischemia group were lower than that in the control group;while RPC ischemia group lower than RPC group.At 24h and 48h after reperfusion,activities of SOD and CAT of spinal cord tissue in control group were lower than that in RPC group;while ischemia group lower than RPC ischemia group.MDA content revealed contrary results.Conclusion:RPC up-regulated activities of antioxidant enzymes,which then scavenge the ROS produced during ischemia-reperfusion and protect the spinal cord from ROS-mediated injury.Activities of SOD and CAT in spinal cord tissue have correlation with the neurological outcome.