地塞米松预处理对氧糖剥夺大鼠血脑屏障通透性的影响

目的探讨地塞米松(dexamethasone,DEX)对氧糖剥夺(oxygen glucose deprivation,OGD)条件下大鼠血脑屏障通透性的影响。方法提取纯化大鼠脑微血管内皮细胞,建立血脑屏障OGD模型。在OGD不同时间点(0、30、60 min),以及DEX预处理OGD 60min时,应用辣根过氧化物酶渗漏实验分析血脑屏障的通透性;应用RT-PCR和western blot法分析大鼠脑微血管内皮细胞的紧密连接相关蛋白claudin-5的mRNA和蛋白的表达变化;同时应用免疫荧光方法观察细胞膜上claudin-5的变化。结果与对照组相比,OGD 30、60min,辣根过氧化物酶流量均显著升高;与OGD 60min相比,DEX预处理显著降低了辣根过氧化物酶流量。与对照组相比,OGD30、60min,claudin-5的mRNA和蛋白表达水平均显著降低;与OGD 60min相比,DEX预处理显著增加了claudin-5的mRNA和蛋白表达。免疫荧光观察claudin-5在细胞膜上的表达,与对照组相比,OGD 60min时claudin-5的表达明显减少,DEX预处理后显著增加了claudin-5的表达。结论 DEX预处理降低了OGD条件下的血脑屏障通透性,其机制之一是DEX增加紧密连接相关蛋白claudin-5的表达。

Effects of Dexamethasone preconditioning on blood-tumor barrier permeability under oxygen glucose deprivation exposure

Objective To investigate the effects of dexamethasone （DEX） preconditioning on the blood-tumor barrier （BTB） permeability under oxygen glucose deprivation （OGD） exposure. Methods After isolation and purify, the rat brain microvascular endothelial cells were used to establish the OGD BBB model in vitro. The permeability of BBB at different time point of OGD （0, 30, 6min） and DEX preconditioning at OGD 60min was detected by HRP leakage test The mRNA and protein expression levels of clandin-5 in rat brain maerevascular endothelial cells were analyzed by RT-PCR and western blot. The distribution of clandin-5 was observed by immunofltaescent staining. Results Compared to control group, the HRP flux increased significantly after OGD 30 min and 60min treatment. The DEX preconditioning reduced the HRP flux significantly compared with OGD 60min group. The mRNA and protein expression levels of claudin-5 decreased significantly after OGD 30 and 60min treatment, compared to control group. After DEX preconditioning, the mRNA and protein expression levels of claudin-5 increased significantly compared to OGD 60min group. The results of immunoflurescent staining showed that the expression level of claudin-5 on the endothelial cell membrane reduced significantly after OGD 60min, compared with control group. The DEX preconditioning up-regulated the expression of claudin-5 significantly. Conclusion DEX preconditioning decreased the BBB permeability under OGD exposure, and the up-regulated tight junction associated protein claudin-5 induced by DEX was one of the potential mechanisms involved in this process.