局灶性脑缺血再灌注致血脑屏障破坏与zileuton的保护作用

目的： 探讨局灶性脑缺血再灌注损伤（CIRI）致血脑屏障(BBB) 通透性破坏的影响因素，观察高选择性5-脂氧合酶（5-LO）抑制剂zileuton的保护作用并分析其机制。方法: 线栓法制备大鼠大脑中动脉闭塞2 h/再灌注24 h模型（MCAO2 h/R24 h），于缺血前2 h、再灌注0、5、10 h，分别灌胃给予zileuton10、50 mg·kg-1。伊文氏蓝示踪剂检测BBB；AutoCAD图像分析软件计算脑水肿程度；RT-PCR法检测脑组织白三烯受体1mRNA（CysLTR1 mRNA）；ELISA法检测血清白三烯B4（LTB4）；免疫组化法检测脑组织水通道蛋白4（AQP4）、基质金属蛋白酶9（MMP-9）蛋白。结果: MCAO2 h/R24 h后,BBB通透性明显增高，出现脑水肿，血清LTB4含量升高，梗塞侧脑组织CysLTR1mRNA表达增强，缺血区与梗塞灶周边缺血半暗带（IP）区AQP4与MMP-9蛋白表达上调； zileuton10、50 mg·kg-1均能有效控制CIRI所致的BBB破坏，改善脑水肿，降低血清LTB4含量,下调脑组织CysLTR1mRNA、AQP4与MMP-9表达。结论: CIRI后BBB通透性明显破坏，zileuton的保护作用与抑制脑组织和循环血液中的5-LO通路活化、下调脑组织缺血区与IP区的AQP4与MMP-9蛋白表达有关。

Effects of 5-lipoxygenase inhibitor zileuton on destruction of blood-brain barrier permeability induced by focal cerebral ischemia-reperfusion injury in rats

AIM: To investigate the influential factors of the blood-brain barrier (BBB) permeability and to observe the effects of zileuton, a selective 5-lipoxygenase inhibitor (5-LO), on focal cerebral ischemia-reperfusion injury (CIRI). METHODS: The right middle cerebral artery of the rat was occluded by inserting a thread through internal carotid artery for 2 h, and then reperfused for 24 h. Zileuton (10, 50 mg·kg-1, po) was orally administered 2 h before ischemia and at 0, 5, 10 h after reperfusion. The permeability of blood brain barrier (BBB) was detected by using Evans blue (EB) as a labelling compound. The degree of cerebral edema was estimated by AutoCAD image analysis software. The mRNA of cysteiny leukotrienes receptor1 (CysLTR1) was detected by RT-PCR. The content of LTB4 in serum was measured by enzyme linked immunosorbent assay (ELISA). The expressions of AQP4 and MMP-9 proteins were measured by immunohistochemical staining method. RESULTS: After middle cerebral artery occlussion 2 h/reperfusion 24 h, the permeability of BBB in the brain tissue of injured side and the brain edema degree were increased. The content of LTB4 in serum was elevated. The expression of CysLTR1 mRNA from the brain tissue of occluded side was enhanced. The expressions of MMP-9 and AQP4 proteins of the ischemia realm and ischemia penumbra (IP) of the infarct focus perimeter were increased. Both 10 and 50 mg·kg-1 doses of zileuton dramatically relieved the BBB permeability destruction and the degree of the brain edema, inhibited the expression of CysLTR1 mRNA in the brain tissue and also reduced the content of LTB4 in serum. The expressions of AQP4 and MMP-9 proteins in the brain tissue were also decreased. CONCLUSION: The permeability of BBB is destroyed after the focal CIRI. The mechanisms of protective effect of zileuton might be attributed to its effects by inhibiting the activation of 5-LO pathways on the brain tissue and circulatory blood, reducing the expressions of AQP4 and MMP-9 proteins of the ischemia and IP realm in the brain tissue.