目的 探讨N-甲基-D-天冬氨酸受体亚单位NR2A/2B表达与缺血再灌注损伤的关系.方法 建立局灶性大脑中动脉阻塞大鼠模型观察缺血2h再灌6～96 h的组织病理学改变,实时荧光定量PCR及Western印迹法测定大脑皮质NR2A/2B mRNA及蛋白表达.结果 大鼠缺血再灌注后6h,皮质开始出现明显病理学改变,12 h可见血管内有淤血,24h梗死区锥体细胞出现严重的核固缩、核溶解,几乎看不到正常神经元,48 h出现大面积角质化,96 h可见炎症细胞浸润.与假手术组相比,再灌组NR2A/2B mRNA于再灌注6 h即开始一直持续明显下降(P＜0.01),再灌12和24 hNR2A/2B mRNA比值均为1:2,偏离正常的1:1,48 h两者的表达开始上调,至96 h NR2A/2B mRNA比值达到1:1；再灌24h后NR2A蛋白表达显著降低(P＜0.05)；NR2B蛋白于再灌6h开始明显降低,一直持续到24 h(P＜0.01),48 h开始上调,96 h后蛋白表达接近假手术组水平.结论 缺血2h再灌注24h后神经元损伤最严重,并与NR2A/2B表达改变存在时间一致性和受体亚型选择性.%OBJECTIVE To observe relationship between cerebral ischemia reperfusion injury and expression of N-methyl-D-aspartate receptors NR2A/2B. METHODS Established middle cerebral artery occlusion (MCAO) model and investigated histopathological changes at different time points between 6 and 96 h after ischemia(2 h) reperfusion injury, as well as to test mRNA levels and expression of NR2A/2B protein in rat cortex by using real-time quantitative polymerase chain reaction (RT-qPCR) and Western blotting. RESULTS The obvious pathological changes of cortex and visible vascular congestion in rats respectively showed at 6 h and 12 h. There were almost no normal neurons cells in infarcted area and severe pyknosis and karyolysis were observed at 24 h. Area homy at 48 h and inflammatory cell infiltration at 96 h were observed. Compared with the sham group, mRNA levels of NR2A/2B began to decrease at 6 h after reperfusion (P <0.01), NR2A/2B mRNA ratio was 1:2 at 12 h and 24 h, and reached to 1:1 at % h. Expression of NR2A protein significantly reduced only at 24 h (P <0.05). Differently, expression of NR2B protein was reduced from 6 h and continued until 24h(P<0.01) , while they began to increase at 48 h, and then reached to normal level at 96 h after reperfusion. CONCLUSION The neurons are most damaged at 24 h after ischemia reperfusion injury and this damage is consistent with the expression of NR2A/2B and might have relationship with receptor subtype selectivity .
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