糖尿病通过抑制VEGF/VEGFR2通路加重大鼠缺血性脑损伤

目的 探讨缺血皮质血管内皮生长因子(vascular endothelial growth factor,VEGF)和VEGF受体2(VEGF receptor 2,VEGFR2)表达对糖尿病大鼠缺血性脑损伤的影响.方法 36只健康雄性Sprague-Dawley大鼠按随机数字表法分为假手术组、脑缺血组和糖尿病脑缺血组.腹腔注射链脲佐菌素制作糖尿病模型,然后再应用栓线法建立大鼠永久性局灶性脑缺血模型.在缺血后24 h进行神经功能缺损评分,氯化三苯基四氮唑染色测量梗死体积,TUNEL法检测凋亡细胞,实时荧光定量聚合酶链反应检测VEGF和VEGFR2 mRNA表达水平,蛋白质印迹法检测VEGF和VEGFR2蛋白表达水平.结果 假手术组无神经功能缺损,无梗死灶,仅有少量凋亡细胞以及少量VEGF和VEGFR2mRNA和蛋白表达.糖尿病脑缺血组神经功能评分(4.25±0.54)分对(2.86±0.73)分;t=5.303,P ＜0.001]、梗死体积(51.69 ±2.26)mm3对(30.15 ±2.08)mm3;=23.166,P＜0.001]和凋亡细胞数量(24.22±1.34)个/HP对(13.28 ±0.37)个/HP;t =27.261,P＜0.001]均较脑缺血组显著增高和增加,而VEGF和VEGFR2 mRNA以及蛋白表达水平则较脑缺血组显著降低(VEGF mRNA:4.74±0.54对6.71 ±0.91,P＜0.001;VEGFR2 mRNA:4.06±0.60对6.16±0.96,P＜0.001;VEGF蛋白:0.99 ±0.13对1.55 ±0.23,P＜0.001;VEGFR2蛋白:4.12±0.74对6.23±0.76,P＜0.001).结论 VEGF/VEGFR2信号通路参与了糖尿病加重脑缺血损伤的过程,VEGF和VEGFR2表达下调可能是糖尿病加重脑缺血损伤的机制之一.

Diabetes mellitus aggravates cerebral ischemia injury in rats by downregulating VEGF/VEGFR2 pathway

Objective To investigate the effect of expressions of endothelial growth factor (VEGF) and VEGF receptor 2 (VEGFR2) in the ischemic cortex on ischemic cerebral injury in rats with diabetes mellitus.Methods A total of 36 healthy male Sprague-Dawley rats were divided into 3 groups:a shamoperation group,a cerebral ischemic group,and a diabetic cerebral ischemic group according to the random number table method.A diabetes model was induced by injection of streptozocin,and then,a permanent focal cerebral ischemic model was induced by the suture method.At 24 h after ischemia,the neurological deficit scores were conducted.The triphenyl tetrazolium chloride staining was used to measure the infarct volume.TUNEL was used to detect the apoptotic cells.Real-time fluorescence quantitative polymerase chain reaction was used to detect the expression levels of VEGF and VEGFR2 mRNAs.Western blot was used to detect the expression levels of VEGF and VEGFR2 proteins.Results In the sham operation group,there were no neurological deficit and infarcts,and there were only a few apoptotic cells and a few expressions of VEGF,VEGFR2 mRNAs and protein.The neurological function score (4.25 ±0.54 vs.2.86 ±0.73);t =5.303,P＜0.001),infarct volume (51.69 ±2.26 mm3 vs.30.15 ±2.08 mm3;t =23.166,P＜0.001),and the number of apoptotic cells (24.22 ± 1.34/HP vs.13.28 ±0.37/HP;t =27.261,P＜0.001) in the diabetic cerebral ischernia group were significantly increased than those in the cerebral ischemic group,while VEGF,VEGFR2 mRNA,and protein expression level were significantly decerased (VEGF mRNA:4.74 ± 0.54 vs.6.71 ± 0.91,P ＜ 0.001;VEGFR2 mRNA:4.06 ± 0.60 vs.6.16 ± 0.96,P ＜ 0.001,VEGF protein:0.99 ± 0.13 vs.1.55 ± 0.23,P ＜ 0.001;VEGFR2 protein:4.12 ± 0.74 vs.6.23 ± 0.76,P ＜ 0.001) compare with the cerebral ischemic group.Conclusions VEGF/VEGFR2 signal pathway participates in diabetes aggravating ischemic cerebral injury.The downregulating of VEGF/VEGFR2 may be one of the mechanisms of diabetes aggravating ischemic cerebral injury.