缺氧预处理对创伤性脑损伤大鼠 Claudin5 表达及血脑屏障通透性的影响

目的探讨缺氧预处理对创伤性脑损伤大鼠脑组织紧密连接蛋白Claudin-5的表达及血-脑屏障通透性的影响。方法204只大鼠随机分为创伤性脑损伤组（T组）96例，缺氧预处理后脑损伤组（H组）96例及对照组12例。T组行自由落体撞击法建立大鼠创伤性脑损伤模型，H组给予3d缺氧预处理后，同法致脑损伤，两组大鼠于伤后1h、4h、8h、12h、24h、3d、7d、14d断头处死。采用干湿重法测脑组织含水量：Real—timePCR和Westernblot检测各组大鼠挫伤区周围脑组织Claudin-5mRNA及蛋白表达变化；IgG法检测血一脑屏障通透性变化。结果T组和H组伤后1hClaudin-5mRNA及蛋白表达开始降低，8～12h降至最低点，1d开始上升，直至伤后14d渐趋于对照组水平；其中H组各时间点Claudin-5mRNA及蛋白表达均高于T组。T组各时间点血一脑屏障通透性及脑组织含水量均明显高于H组（P〈0．05），且两组均高于对照组（P〈0．05）。结论缺氧预处理可在创伤性脑损伤早期上调紧密连接蛋白Claudin-5的表达，维持血-脑屏障完整性，减轻脑水肿。

Effect of hypoxic preconditioning on claudin-5 expression and blood-brain barrier permeability after traumatic brain injury in rats

Objective To explore the effect of hypoxic preconditioning on tight junction protein claudin-5 and blood-brain barrier permeability after traumatic brain injury in rats. Methods 204 rats were randomly assigned into traumatic brain injury group （group T, n = 96）, traumatic brain injury with hypoxic preconditioning group （group H, n = 96） and control group （n = 12）. The rats in group T were established traumatic brain injury model with freefall impact method, and the rats in group H were treated by the same methods after 3 days of hypoxic preconditioning, then the rats in groups T and H were decapitated at time point of 1 h, 4 h, 8 h, 12 h, 24 h, 3 d, 7 d, and 14 d after injury. The wet and dry weight method was used to detect the brain water content of rats. Real-time PCR and Western blotting were used to detect the changes of claudin-5 mRNA and protein in brain contusion area. IgO method was used to detect the changes of blood-brain barrier permeability. Results Claudin-5 mRNA and protein expressions of groups T and H began to decrease at 1 h, fell down to the bottom 8 to 12 h, began to rise gradually on 1 d, and tended to the level of control group until 14 d after injury. Additionally, clandin-5 mRNA and protein expressions in group H were higher than in group T at every time point. The blood-brain barrier permeability and brain water content at each time point in group T were significantly higher than those in group H （P 〈 0.05）, and those in the two groups were higher than those in control group （P 〈 0.05）. Conclusion Hypoxic preconditioning can up-regulate claudin-5 expression in early traumatic brain injury, protect the integrity of blood-brain barrier and reduce cerebral edema.