缓激肽选择性增加局部脑缺血大鼠血脑屏障的通透性

目的　研究颈动脉灌注小剂量缓激肽对缺血后血脑屏障通透性的影响及机制。方法　免疫组化分析正常脑组织的缓激肽B2受体所在。大鼠大脑中动脉结扎 1h或 2h再灌流 1h。用放射自显影方法检测缓激肽对血脑屏障通透性的变化。WesternBlot方法检测bNOS ,iNOS和B2受体。NOS检测盒检测NOS的活性。结果　正常脑组织毛细血管内皮未见B2受体表达 ,在神经细胞上发现B2受体的表达。缺血 2h再灌流1h缓激肽灌注缺血区血脑屏障通透性显著增加。WesternBlot结果提示 ,在缓激肽灌注组和对照组间 ,缺血皮质区bNOS和B2受体没有明显变化 ,各组中均未检测出iNOS。缓激肽灌注组的NOS活性显著高于对照组。结论　正常脑组织毛细血管内皮未表达B2受体 ,神经细胞上可见B2受体的表达。灌注小剂量缓激肽能选择性增加局部脑缺血大鼠血脑屏障的通透性

Bradykinin Selectively Increases Blood-Brain Barrier Permeability after Focal Ischemia in Rats

Objective To study the effect and mechanism of blood-brain barrier (BBB) permeability after focal ischemia in rats by intracarotid infusion of low dose bradykinin. Method Double immunohistochemical analysis was used for determining the localization of B2 receptor on normal brain tissue. The right middle cerebral artery was occluded 1 or 2 hr followed by 1 hr reperfusion. The blood-brain barrier permeability was determined autoradiography. bNOS, iNOS and B2 receptor protein were analysed by Western Blot , and NOS activity was determined by NOS detect TM assay kit. Results The capillary endothelial cells in the normal brain tissue did not express B2 receptor, but neuronal cells expressed B2 receptor. The Ki value was significantly increased in ischemic areas in 2 hr ischemia plus 1 hr reperfusion by bradykinin. bNOS and B2 receptor did not reveal significant change in ischemic cortex between bradykinin perfusion group and control group. iNOS levels were undetectable in each group. NOS activity was significantly increased in bradykinin perfusion group comparing with control group. Conclusion The capillary endothelial cells in the normal brain tissue do not express B2 receptor,but neurons express B2 receptor. A low dose infusion of bradykinin could selectively open the blood brain barrier in the ischemic area caused by 2 hr middle cerebral artery occlusion followed by 1 hr reperfusion.