大鼠慢性脑缺血认知、情绪及小胶质细胞的变化

目的：利用大鼠双侧颈总动脉永久性结扎（permanent,bilateral common carotid artery occlusion,BCCA）方法制作慢性脑缺血模型,观察42 d 与56 d 两时间点在认知、情绪、组织状态的差异及小胶质细胞状态改变,在模型制作时间上为慢性脑缺血实验研究提供依据。方法雄性 SD 大鼠采用抽签法随机分为42 d-假手术组（42 d-Sham）、42 d-模型组（42 d-Model）、56 d-假手术组（56 d-Sham）及56 d-模型组（56 d-Model）。采用 Morris 水迷宫、新旧物体识别和旷场试验3种方法评价大鼠认知能力和情绪, HE 染色观察大鼠海马组织状态改变,用脑组织冰冻切片 Iba1免疫荧光染色观察各组海马及皮质小胶质细胞的活化状态。结果Morris 水迷宫试验结果显示,与 Sham 组相比,Model 组大鼠出现认知障碍,56 d 较42 d 下降更为显著,表现为逃避潜伏期延长,穿越平台次数减少。新旧物体识别试验结果表明,Model 组大鼠认知能力下降,表现为新旧物体分辨指数下降,新物体探索时间减少,但42 d 与56 d 手术组及 Sham 组之间差异无统计学意义。旷场试验结果提示,Model 组大鼠出现焦虑样行为,表现为直立次数和穿格次数明显增多。 HE 染色结果提示 BCCA 模型42 d 及56 d 在双侧海马均未出现明显的组织状态改变。免疫荧光结果显示,Iba1的表达在 Model 组与 Sham 组差异有统计学意义,Model 组海马与皮质中小胶质细胞数量均较多,染色加深,胞体增大,突起增多、变短,呈“阿米巴样”。结论 BCCA 法制作的大鼠慢性脑缺血模型42 d 即出现认知能力下降,小胶质细胞出现活化改变,提示42 d 即可作为慢性脑缺血动物实验模型制作的备选时间点。56 d 较42 d 认知能力下降更为显著,提示随时间延长,改变更为显著。但42 d 及56 d 均未出现 HE 染色可观察到的组织状态学改变。

Changes in cognition,emotion and microglia condition caused by chronic cerebral ischemia in rats

Objective To observe the cognition, emotion, tissue condition and microglia condition after chronic cerebral ischemia caused by bilateral common carotid artery（BCCA） occlusion on 42nd and 56th day, and provide the basis to understand forming time of chronic cerebral ischemic model. Methods Sprague-Dawley（SD） rats were divided into 4 groups by sortition randomization method： 42 d-Sham, 42 d-Model, 56 d-Sham and 56 d-Model. Morris water maze, object location test and open field test were measured to evaluate cognition and emotion. To observe tissue condition of hippocampus, we chose H＆amp;E staining. The microglia activity was measured by Iba1 immunofluorescent staining（IF）. Results The result of morris water maze showed that compared with the Sham group, the cognition of Model group was decreased, the decrease was more significant in 56 d-Model. Model group showed that the escape latency was longer, and the frequency of platform crossing was reduced. The result of object location test also showed the cognition of Model group was decreased. The discrimination index and explore time of new object was reduced. But there were no significant difference between them. The open field test showed vertical number and crossing number of Model group increased clearly, indicating that Model group had anxiety behavior. The H＆amp;E staining result showed that there were no changes in hippocampus tissue condition in the four groups. The IF staining showed that there were significant differences between the Model group and Sham group in Iba1 protein expression. Number of microglia in Model group was higher, colour was deepening, the cell was bigger, and the protuberances were increased and shortened, the protuberances like amoebocyte. Conclusion The cognition of rats was reduced at 42 days after BCCA operation, and the microglia were activated. It indicated that we can choose 42 day as forming time of chronic cerebral ischemia model. According to the cognition of 56 d-Model was worse than 42 d-Model, we suspect t