前脑缺血再灌流后大鼠海马NMDA受体亚单位NR2A和NR2B蛋白质表达的变化

CHANGES IN PROTEIN EXPRESSION OF NMDA RECEPTOR SUBUNITS NR2A AND NR2B IN RAT HIPPOCAMPUS FOLLOWING TRANSIENT FOREBRAIN ISCHEMIA

用免疫组织化学和图像处理方法 ,观察分析了大鼠前脑缺血 15 min后再灌流 2 h～ 7d的海马结构各区域 NMDA受体亚单位 NR2 A和 NR2 B的表达变化规律及其差异 ,藉以探讨二者在缺血性脑损伤中的作用。结果显示 :( 1) NR2 A在 CA1 区和CA3 区的表达于再灌早期表现为小幅度下降 ( P<0 .0 5 ) ,此趋势在 CA3 区可以逆转 ;但在 CA1 区逐渐加剧 ,第 7d时降至 2 1% ,NR2 A在齿状回的表达几无改变 ;( 2 )与 NR2 A不同 ,再灌后 2 h,NR2 B在 CA1 区的表达即较对照组增高 ( P<0 .0 5 ) ,并持续到再灌后 2 4h,之后转而急剧下降 ,至第 7d仅余 11% ;在 CA3 区及齿状回 ,再灌后 6～ 48h,NR2 B的表达也较对照组增高 ( P<0 .0 5 ) ;在再灌后 72 h则恢复至对照组水平。结果提示 ,缺血性脑损伤后 NR2 A和 NR2 B表达变化的不同可能是造成 CA1 区。

By immunohistochemistry and computer-assisted image analysis, we investigated the changes in protein expression of NMDA receptor subunits NR2A and NR2B in rat hippocampal subfields following transient forebrain ischemia. The transient forebrain ischemia was produced by occluding four-vessels for 15 minutes and reperfusing for 2 hours to 7 days. The expression of NR2A in CA 1 and CA 3 fields decreased lightly at early reperfusion (P<0.05). This decrease was reversible in CA 3 field, but irreversible in CA 1 field and down to 21% of sham-operated control at 7 d. There was no significant change of NR2A in dentate gyrus (DG). In contrast, the expression of NR2B in CA 1 field increased early at 2 h of reperfusion (P<0.05) and sustained to 24 h of reperfusion. Then it reduced sharply and left only 11% compared to control at 7 d. In CA 3 field and DG, the expression of NR2B enhanced from 6 h to 48 h of reperfusion relative to control (P<0.05), but came back to the control level at 72 h. The results indicate that the different expression of NR2A and NR2B following cerebral ischemia may contribute to the differences of vulnerability to ischemic-reperfusion injury among CA 1, CA 3 and DG. (Figures 3～12 on plate 24)