小鼠局灶性脑缺血模型中细胞间粘附分子-1表达升高

目的 白细胞可以导致缺血细胞损伤，内皮细胞上表达的细胞间粘附分子－１（ＩＣＡＭ－１）有利于白细胞迁移至组织。本研究目的是对小鼠大脑中动脉栓塞（ＭＣＡＯ）后脑内ＩＣＡＭ－１ 蛋白在组织中表达和含量进行检测。方法 通过对成年雄性ＣＤ－１ 小鼠使用血管腔内尼龙线栓塞术，造成０、３、６、１２、２４、４８ 和７２ ｈ 的持续性大脑中动脉栓塞。缺血程度由激光多普勒流量仪确定，缺血脑组织ＩＣＡＭ－１ 的阳性表达由免疫组化技术检测，并用免疫沉淀和Ｗｅｓｔｅｒｎ 印迹来定量。结果 在大脑中动脉栓塞后，小鼠缺血脑半球的表面脑血流量减少到基准值的９％ ～１５％ 。各组间大脑中动脉栓塞过程中的脑血流量无显著差异。免疫组化技术显示，缺血中心区和末影区都见ＩＣＡＭ－１ 阳性的微血管内皮细胞，从缺血中心到缺血边缘区微血管内皮细胞表达ＩＣＡＭ－１ 出现增高的趋势。免疫沉淀和Ｗｅｓｔｅｒｎ 印迹分析结果表明，缺血区ＩＣＡＭ－１的表达在大脑中动脉栓塞后３ ｈ 增高，６～１２ ｈ 达到高峰，并持续到７２ ｈ。结论 研究表明，在持续性大脑中动脉栓塞的小鼠中检测到ＩＣＡＭ－１ 表达明显升高，因为在持续局灶性大脑中动脉缺血后ＩＣＡＭ－１ 可介导白细胞和内皮细胞粘附。

U0126 PREVENTS ERK PATHWAY PHOSPHORYLATION AND INTERLEUKIN-1β mRNA PRODUCTION AFTER CEREBRAL ISCHEMIA

Objective To study the role of extracellular signal-regulated kinase (ERK) in cerebral ischemia and the mechanism of protective effects of U0126 (1,4-diamino-2,3-dicyano-1,4-bis[2-aminophenylthio] butadiene) on ischemic brain. Methods Mice underwent left middle cerebral artery occlusion (MCAO) by introducing a suture in the lumen. U0126 was injected intravenously through the internal jugular vein. The immuno-activity of phosphorylated ERK1/2 (pERK1/2), phos-phorylated mitogen activated protein kinase kinase (pMEK), and phosphorylated Elk-1 (pElk-1) was assessed by Western blot analysis and immunohistochemistry. Interleukin (IL)-1βmRNA level was measured by ribonuclease protection assay. Results Phosphorylated ERK1/2 in 2 hours MCAO mice was down-regulated after intravenous injection of U0126. The inhibition was dose dependent and treatment time related. pMEK and pElk-1 were also reduced in a similar fashion after U0126 treatment. IL-1βmRNA increased after 1 and 2 hours of MCAO. After injection of U0126, it was down-regulated during 1 to 4 hours after MCAO. Conclusion Intravenous administration of the MEK inhibitor U0126 inhibits pMEK, pERK1/2, and pElk-1 up-regulation induced by cerebral ischemia. The protective effect of U0126 against ischemic injury is probably resulted from the reduction of IL-1βmRNA via the inhibition of ERK pathway.