脑缺血预处理对脑缺血大鼠血管生成素-1及其受体Tie-2mRNA表达的影响

Effect of cerebral ischemic preconditioning on the expressions of angiopoietin-1 real its receptor Tie-2 mRNA in cerebral ischerria in rats

目的探讨脑缺血预处理对脑缺血大鼠血管生成素-1（angiopoietin-1，Ang-1）及其受体Tie-2 mRNA表达的影响。方法99只Wistar大鼠随机分成假手术组（n=9）、非缺血预处理组（nonischemic preconditioning NIP）（n=45）和缺血预处理组（ischemic preconditioning,IP）（n=45），后两组再随机分为缺血再灌注1d、3d、7d、14d和21d等5个亚组（每组n=9）。线栓法建立短暂性大脑中动脉闭塞（middle cerebral artery occlusion，MCAO）模型进行局灶性缺血预处理（缺血10min后恢复灌注）。2,3,5-氯化三苯基四氮唑染色法测定脑梗死体积。原位杂交法检测Ang-1／Tie-2 mRNA表达水平。结果IP组1d、3d和7d亚组梗死体积显著小于NIP组相应亚组（P均〈0．01），IP组3d和7d亚组Ang-1 mRNA以及1d、3d和7d亚组Tie-2 mRNA表达较NIP组显著性上调（P均〈0．05）。IP组3d亚组梗死体积缩小最显著（P〈0．05），7d亚组Ana-1 mRNA表达显著上调，而其受体Tie-2 mRNA表达高峰出现在IP后3d，并持续至7d。Pearson相关性分析显示，IP组Ang-1／Tie-2 mRNA表达水平与梗死体积呈显著性负相关（P〈0．01）。结论Ang-1和Tie-2mRNA在缺血预处理后产生脑缺血耐受时间窗内（预处理后1～7d）表达上调，其中Ang-1可能主要作用于脑缺血耐受的后期阶段。

Objective To investigate the effect of cerebral ischemic preconditioning （IP） on the expressions of angiopoietin-1 （Ang-1） and its receptor Tie-2 mRNA in cerebral ischemia in rats. Methods Ninety-nine Wistar rats were randomly assigned to three groups： sham operation （n = 9）, non-ischemic preconditioning （NIP） （n =45）, and IP （n =45）. The latter two groups were redivided into 5 subgroups： ischemia-reperfusion 1, 3, 7, 14, and 21 days （n =9 in each group）. A model of transient middle cerebral artery occlusion （MCAO） was induced by the intraluminal suture method for focal IP （ischemia for 10 minutes and restoring perfusion）. Infarct volume was determined by 2,3,5-triphenyltetrazolium staining. The expression levels of Ang-1/Tie-2 mRNA were detected by in situ hybridization. Results The infarct volumes in the 1-, 3-, and 7-day subgroups of the IP group were significantly smaller than those in the relative subgroups of the NIP group （all P 〈 0. 05）. The expression of Ang-1 mRNA in the 3- and 7-day subgroups of the IP group and the expression of Tie-2 mRNA in the 1-, 3-, and 7-day subgroups of the NIP group were upregulated significantly （all P 〈0. 05）. The infarct volume in the 3-day subgroup of the IP group was reduced most significantly （P 〈 0. 05）. The expression of Ang-1 mRNA in the 7-day subgroup was upregulated significantly, and the peak expression of its receptor Tie-2 mRNA appeared at day 3 after IP and continued to day 7. Pearson correlation analysis showed that the expression levels of Ang-1/Tie-2 mRNA were significantly negatively correlated with infarct volume （P 〈 0. 01）. Conelusiom The expression of Ang-1/Tie-2 mRNA in the IP group was upregulated within the time window of ischemic tolerance （1 - 7 days after preconditioning）, in which Ang-1 may mainly act on the later stage of the cerebral ischemic tolerance.