前脑缺血再灌流后大鼠海马 NMDA受体亚单位NR1蛋白的表达变化

目的　观察大鼠前脑缺血再灌流后海马各区域NMDA受体亚单位NR1表达的变化和差异 ,探讨NR1在缺血性脑损伤中的作用。　方法　免疫组织化学和图像处理技术。　结果　 1 在前脑缺血再灌流后早期 ,海马各区域NR1的表达水平显著下降 (P <0 0 5 )。CA1区 ,下降趋势持续存在且不可逆 ,直至再灌流后第 7d ,NR1在该区域的染色强度降至对照组的 17% (P <0 0 5 )。CA3区及齿状回 ,NR1的表达下降是可逆的 ,再灌流后 72h ,齿状回的表达恢复正常 ,再灌后第 7d ,CA3区的表达也恢复到对照组的 96 % ,两组间染色强度无显著差异。 2 在迟发性神经元坏死出现前的缺血再灌流的早期 ,NR1在CA1区、CA3区及齿状回表达下降的幅度不一致 ,再灌后 6h以前 ,CA1区的下降幅度明显小于CA3区及齿状回 (P <0 0 5 ) ,再灌后 12h ,CA1区的下降幅度仍低于CA3区 (P <0 0 5 )。结论　短暂性前脑缺血后 ,NR1在海马CA1区、CA3区及齿状回表达下降的幅度和可逆性存在显著差异 ,这种差异可能是造成CA1区缺血敏感性的重要原因。

CHANGES IN PROTEIN EXPRESSION OF NMDA RECEPTOR SUBUNIT NR1 IN RAT HIPPOCAMPUS FOLLOWING TRANSIENT FOREBRAIN ISCHEMIA

Objective To observe the changes in protein expression of NMDA receptor subunit NR1 in rat hippocampal subfields following transient forebrain ischemia. Methods immunohistochemistry and computer-assisted image analysis techniques were used. Results Early stage after reperfusion,NR1 protein expression levels were lower than that of sham control in all hippocampal subfields(P<005).The trend of decreased expression was found at any time after reperfusion in the CA1 subfield.By day 7 postchallenge,the expression levels of NR1 were only 17% of the control in the CA1 subfield(P<005).In the dentate gyrus and the CA3 subfield,the expression levels of NR1 recovered gradually after it got the lowest at 6h and 12h postchallenge,and finally recovered to the levels of the control at 72h and 7d. On the other hand,before the time that the expression of NR1 in the CA3 subfield and the dentate gyrus started to recover,the decreasing of NR1 expression in the CA1 subfield was less than that in the CA3 subfield and in the dentate gyrus(P<005).Conclusion The results indicated that the alterations of NR1 expression level were different in different hippocampal subfields and these differences might account for the ischemica-vulnerable nature of the CA1 subfield partly.