大鼠感染性脑水肿时NMDA受体的变化

The effect of infectious brain edema on NMDA receptor binding in rat's brain

测定百日咳菌液（ＢＰ）所致大鼠感染性脑水肿（ＩＢＥ）对３ＨＭＫ８０１与大脑皮层神经细胞特异结合的影响。从大鼠左颈总动脉注入ＢＰ，制备ＩＢＥ模型。雄性ＳＤ大鼠随机分３组：①对照组（ＮＳ，ｎ＝１１）；②ＩＢＥ组（ＢＰ，ｎ＝１２）；③ＭＫ８０１＋ＢＰ预处理组（ＭＫ８０１，ｎ＝４）。０２ｍｌ／ｋｇ体重生理盐水或ＢＰ注入左颈总动脉作为ＮＳ或ＢＰ组；每天腹腔注射０５ｍｇＭＫ８０１／ｋｇ体重，共２天，然后注入ＢＰ为ＭＫ８０１组。注射ＢＰ２４小时后断头取脑。Ｎ甲基Ｄ天冬氨酸（ＮＭＤＡ）受体与３ＨＭＫ８０１的特异结合用放射配体结合分析法测定，Ｓｃａｔｃｈａｒｄ作图。结果，ＮＳ及ＢＰ组的Ｂｍａｘ分别为０６２３±００８２和０６０６±００８７ｐｍｏｌ／ｍｇ蛋白质（ｔ＝０４８，Ｐ＞００５），Ｋｄ分别为４３１±４２和３０５±３０μｍｏｌ／Ｌ（ｔ＝７８，Ｐ＜００５）。ＭＫ８０１预处理减少ＮＭＤＡ受体的特异结合。表明在此脑水肿模型中ＮＭＤＡ受体总数未发生变化，但亲和力明显增高，其增高能被预先腹腔注入的ＭＫ８０１抑制。

PURPOSE The effect of the infectious brain edema (IBE) induced by Bordetella Pertussis (BP) on the specific binding of 3H MK 801 in rat's brain in vivo was determined. METHODS [WT5”BZ]BP was injected via left internal carotid artery in rat model of infectious brain edema. Male SD rats were divided into three groups: ①Group control (NS, n=11); ②Group IBF (BP, n=12); ③Group pretreatment of MK 801+PB (MK 801, n=4). Normal saline or BP 0 2ml/kg was injected into left internal carotid artery in NS and BP group respectively. MK 801 0 5mg/kg per day was injected i p two days before injection of BP in group MK 801. Rats were killed by decapitation at 24 hours after injection of BP. The specific binding of N methyl D aspartate (NMDA) receptor were measured with 3H MK 801 in the neuronal membrane of cerebral cortex. The Scatchard plots were performed. RESULTS The B max values were 0 623±0 082 and 0 606±0 087pmol/mg protein in group NS and BP respectively (t=0.48, P>0 05). The Kd values were 43 1±4 2 and 30 5±3 0nmol/L in group NS and BP respectively (t=7.8, P<0 05). The specific binding of NMDA receptor was decreased by pretreatment of MK 801. CONCLUSIONS [WT5”BZ]The total number of NMDA receptor had not changed, whereas its affinity increased significantly in the model of brain edema induced by pertussis bacilli in rat. The increase of affinity of NMDA receptor can be blockaded by MK 801 pretreatment in vivo.