克罗卡林预处理对脑缺血／再灌注大鼠水通道蛋白4表达及血脑屏障通透性的影响

Investigating the effects of the cromakalim pretreatment on the expression of aquaporin-4 and the blood-brain barrier permeability in acute cerebral ischemia/reperfusion injury mice

目的研究ATP敏感性钾通道（KATP）开放剂克罗卡林对大鼠脑缺血，再灌注（ischemia／reperfusion，YR）后水通道蛋白4（aquapofin4，AQP-4）表达及血脑屏障（blood-brain-barrier，BBB）通透性的影响。方法30只健康雄性Wistar大鼠参照随机数目表按三组安全随机分组法分为假手术组（A组）、脑I／R对照组（B组）、脑I／R＋克罗卡林组（C组），每组10只。应用线栓法建立大鼠大脑中动脉缺血（middl ecerebral artery occlusion，MCAO）模型，脑缺血2h再灌注24h后，观察动物神经行为缺损，并取脑检查。Bedemon法评价动物的神经行为功能，应用苏木素咿红（HE）染色观察病理变化，干湿重法测定脑组织含水量，并通过免疫组织化学方法检测IgG及AQP-4的表达。结果与A组脑含水量（78．2±1．3）％，IgG、AQP-4蛋白表达（O．0±0．0，13．6±1．5）相比，B组脑含水量（81．3±1．2）％，IgG、AQP-4蛋白表达（2．4±0．4，19．8±1．9）均明显增高（P〈0．05），而C组脑含水量（79．5±0．6）％变化则差异元统计学意义（P〉0．05），但IsG与AQP-4的表达（1．1±0．2，15．7±1．2）也明显升高（P〈0．05）；与B组相比，C组神经行为缺损评分明显减低（P〈0．05），IgG、AQP4（1．1±0．2，15．7±1．2）蛋白表达及脑组织含水量（79．5±0．6）％亦明显降低（P〈0．05）。结论脑I／R损伤过程中，克罗卡林可能通过降低AQP4的表达和BBB的通透性，减轻脑水肿，发挥脑保护作用。

Objective To investigate the effects of ATP-sensitive potassium channel openers （Cromakalim） on the expression of aquaporin-4 and permeability of blood-brain barrer （BBB） after cerebral ischemic/reperfusion. Methods Thirty healthy male Wistar rats were randomized into three groups for different conditioning, the sham-operated group（A, n=10）, the cerebral I/R group（B, n=10）, and the cerebral I/R＋Cromakalim group （C, n=10）. Intraluminal suture methods were applied to establish the middle cerebral artery occlusion（MCAO） model with occlusion 2 h and reperfusion 24 h. the neurobehavioral function was evaluated with Bederson＇s test, and the pathological changes were observed with hematoxylin-eosin（HE ） staining. The water content of brain was evaluated by wet-dry weight method, and the expressions of IgG and AQP-4 in brain were observed by immunohistochemistry staining. Results In comparison with group A＇s water content（78.2±1.3）% and expressions of IgG and AQP-4 （0.0±0.0,13.6±1.5 ）, the expressions of IgG and AQP-4（2.4±0.4,19.8±1.9） and the water content （81.3 ± 1.2）% in group B both were significantly higher （P〈0.05）. However, in group C, the water content （79.5±0.6）%was similar to group A（78.2±1.3）%. Interestingly, the expressions of IgG and AQP-4（ 1.1±0.2, 15.7±1.2） of group C were higher than that of group A＇s （P〈0.05）; compared with group B, The neurobehavioral deficit scores were obviously reduced, the expressions of IgG and AQP-4 （1.1±0.2,15.7±1.2） and the water content （79.5±0.6）% were significantly lower in group C （P〈0.05）. Conclusion Cromakalim maybe can alleviate cerebral edema via reducing permeability of blood-brain barrier and inhibit the expression of AQP-4 in cerebral ischemia/reperfusion mice.