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目的：采用枕大池内注入脂多糖（lipopolysaccharides, LPS）的方法建立大鼠脑水肿模型，观察脑组织病理形态学变化，脑组织含水量（brain water content, BWC），血脑屏障（blood brain barrier, BBB）的紧密连接蛋白Occludin 和水通道蛋白-4（aquaporin 4, AQP4）表达水平的动态变化，研究AQP4 及Occludin 与脑水肿形成的关系，及其可能的作用机制，为临床脑水肿的治疗提供理论依据。方法：选用Wistar 健康成年大鼠，随机分为正常对照组，生理盐水组和脂多糖组，后两组的观察时间点选定于造模后3 h、6 h、12 h、24 h、72 h。采用经皮穿刺枕大池内注入脂多糖的方法制备脑水肿动物模型，正常对照组、生理盐水组及脂多糖组分别于各时间点进行开颅取脑，测定脑组织含水量，通过HE 染色法观察脑组织的病理形态学变化，应用Western blot 方法检测occludin 的表达变化。应用RT-PCR 技术测定脑组织内AQP4mRNA的表达变化。结果：生理盐水组各时间点中有少量AQP4mRNA 及occludin 蛋白的表达，与正常对照组之间无显著性差异；脂多糖组在造模后3 hAQP4 的mRNA表达开始增加，6-12 h达高峰，此后明显下降，随后表达开始减弱，24-72 h表达显著低于生理盐水组；occludin 蛋白表达下降出现于造模后3 h，12-24 h下降更明显， 72 h表达开始升高。结论：枕大池内注入脂多糖（LPS）所建立脑水肿模型中，脑组织含水量及血脑屏障通透性增加，病理学特点是血管源性脑水肿出现早且持久，后期伴有细胞毒性脑水肿的改变。AQP4 早期表达增强是胶质细胞的适应性反应，与血脑屏障的破坏有关，促进了血管源性脑水肿的发生。后期AQP4 表达减弱是机体内在防御机制的表现，同时又促进细胞毒性脑水肿的形成。occludin 在脑组织中表达量随脑水肿的加重而降低，即与脑水肿的程度呈负相关,目前认为这与脑水肿时内皮细胞通透性增加，血脑屏障的通透性改变，导致occludin 的表达下调有关，促进了血管源性脑水肿的发生。针对以上特点，我们可以进一步研究调控AQP4 及occludin 表达的药物，从而减轻脑损伤后脑水肿的程度，为脑水肿的治疗提供新的临床策略。关键词：脑水肿；AQP4；血脑屏障；occludin 中图

英文摘要:

Objective:To establish the rat models of brain edema by intracisternal administration of lipopolysaccharides (LPS), to observe the changes of brain pathology, brain water content (BWC), Tight Junctions (TJs) Occludin of blood brain barrier (BBB), the expression level of aquaporin-4 (AQP4), and to study the role and impossible mechanism of aquaporin-4 and Tight Junction Occludin of blood brain barrier in edema formation, and provide theoretical basis for the clinical therapy.Methods:Adult Wistar rats were randomly divided into three groups: normal control (NC) group, normal saline (NS) group, and LPS group. The last two groups were examined at 3 h, 6 h, 12 h, 24 h, 72 h. Brain edema models were induced by intracisternal administration of LPS. Brain water content was measured according to the wet-dry weight method. Pathological changes were observed through light microscope after HE staining. AQP4 mRNA expression was detected by RT-PCR, and the expression of Occludin was measured by Western blot. Results:In NS group, brain water content, the expression of AQP4 mRNA and Occludin were no significant difference compared with those of NC group; in LPS group, cerebral edema was gradually increased after injected LPS and peaked during 6 h-12 h, AQP4 mRNA expression was up-regulated compared with NS group and peaked during 6 h-12 h then started to down-regulated. On the contrary, the expression of Occludin decreased obviously during 12-24 h, and increased at 72 h.Conclusion:In the animal model of brain edema established by intracisternal administration of LPS, the water content in brain and the blood brain barrier ( BBB) permeability was increased. Vasogenic brain edema showed early and lasting in pathological characteristics, accompanied by cytotoxic brain edema later. The expression of AQP4 on theearly time is adaptation reaction of astrocytes, which is related to the breaking of BBB and accordingly induce the vasogenic edema. The expression of AQP4 which reduced rapidly latterly is the performance of body defense mechanism, at the same time, the formation of cytotoxic edema was. The expression of Occludin in brain tissue is reducing with the worse of the brain edema, which means negative correlation forms between the expression of Occludin and the extend of brain edema, it is currently believed that is related to the increasing permeability of BBB. Above all, we can do further research on drugs which regulate the expression of AQP4 and Occludin to decrease the edema after brain damage and provide new clinical strategy of therapeutic intervention in brain edema.

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