摘要
Abstract
Objective To investigate the expression of vascular endothelial growth factor(VEGF) and changeof microvascular density(MVD) in the rat model of brain ischemic tolerance induced by ischemiapreconditioning.Methods Ninety-Nine Wistar rats were randomly assigned to three groups: sham surgery(n=9),non-ischemic preconditioning (NIP, n=45), and ischemic preconditioning(IP, n=45). The NIP groupand IP group were equally divided into five subgroups according to time of ischemia-reperfusion,including 1, 3, 7, 14 and 21 days subgroups. For IP, the rats were given middle cerebral arteryocclusion(MCAO) for 10 minutes. At 1, 3, 7, 14 and 21 days after IP, the rats were given the secondMCAO for 2 h followed by 22 h reperfusion. In the NIP group, pre-ischemia was replaced by shamsurgery. The sham surgery group received the sham surgery twice. Brain sections were stainedwith 2.3.5-triphenyl tetrazolium ch(TTC) for surveying the volume of infraction. The expressionof microvascular density was determined by immunohistochemical staining and the expression ofVEGF mRNA was determined by in situ hybridization.Results ① Intergroup comparison:Both the infarct volume and the expression of VEGF mRNA of animals in the sham surgery group were zero, compared with the NIP group, infarct volume significantly decreased in the 1, 3, 7 days subgroups of IP group(P<0.001). The expression of VEGF mRNA significantly increased in the ischemic hemisphere at 1, 3, 7 days subgroups of IP group(P:0.002, 0.001, 0.001). The expression of MVD significantly increased at 3, 7 days subgroups(.P:0.012, 0.001). ②In the IP group, infarct volume significantly decreased in the 3 days subgroups(P<0.05). The expression of MVD at 7 days, VEGF mRNA at 3 days significantly increased compared with other groups(P<0.05).③There was a positive correlation between expression of VEGF mRNA and change of MVD, but was not obviously(r=0.472, P=0.017). Conclusion Ischemic preconditioning upregulated the expression of VEGF mRNA and MVD, and they may play important roles in the process of brain ischemic tolerance.关键词
脑缺血/血管内皮生长因子类/血管形成/大鼠Key words
Brain ischemia/ Vascular endothelial growth factors/ Angiogenesis/ Rats
