线栓法制备大鼠局灶性脑缺血模型的改进及评价

背景:大脑中动脉闭塞法制备的局灶性脑缺血模型比较符合人类脑梗死的发病过程,但在建立模型的过程中,有一些问题如线栓直径选择、插入深度等不适当会导致模型失败。目的:进行大脑中动脉闭塞法局灶性脑缺血模型的改进。设计:单因素设计,动物实验。单位:广州医学院附属广东省妇女儿童医院儿科。材料:实验于2002-01/2004-03在广东省实验中心进行。取健康Wistar大鼠20只,随机分为假手术组和模型组2组,每组10只。方法:模型组首先分离、结扎颈外动脉和颈总动脉,由颈总动脉到颈内外动脉分叉之间的切口插入线栓,插入深度(2.0±0.2)cm,插入到不能再进为止,然后轻抽2mm。线栓为直径0.2mm的尼龙线,线栓头端先用融化的石蜡处理。血循环阻断时间为3h。假手术组在将尼龙线插入后退出时,轻拉尼龙线使头端退回到颈总动脉中即可。主要观察指标:①神经行为评定:缺血后3,12h进行,0～4分,评分越高神经功能缺陷越重,1～3分为模型成功。②脑梗死体积:缺血12h后断头取脑,20g/L红四氮唑染色,计算脑梗死体积百分率。③光镜下观察病理改变。结果:20只大鼠全部进入结果分析。①模型组10只大鼠中8只出现向对侧倾倒和/或向外画圈,并见结扎侧霍纳氏征阳性(3分);1只表现为不能完全伸展结扎对侧的爪(1分),一只未出现神经症状。②模型组大体病理见栓塞侧脑组织肿胀,较对侧增大,颜色苍白;红四氮唑染色显示栓塞侧皮质、基底核和丘脑呈现苍白色,假手术组脑组织呈现红色,界限清楚。③假手术组无梗死,模型组脑梗死体积百分率为(22.40±4.52)%。结论:制备成功的模型要求合适直径的线栓、插入深度和阻断时间。

Improvement and evaluation of establishing middle cerebral artery occlusion model by nylon strand

BACKGROUND: Focal ischemic model made by middle cerebral artery occlusion (MCAO) is much similar to the process of onset in human cere bral infarction, whereas in the process of modeling some problems such as selection of nylon strand with improper diameter and inserted depth would result in modeling failure. OBJECTIVE: To improve MCAO model of focal cerebral infarction. DESIGN: Single-factor design, animal experiment. SETTING: Department of Pediatrics, Affiliated Maternal and Children's Hospital of Guangzhou Medical College. MATERIALS: The experiment was conducted in the Experimental Center of Guangdong Province from January. 2002 to March 2004. A total of 24 healthy Wistar rats were randomly divided into sham-operation group and model group with 10 rats in each group.METHODS: In rats of the model group, the common carotid artery (CCA) and external carotid artery (ECA) were isolated and ligated. A strand was inserted via the incision on CCA near the furcation between CCA and ECA as deep as possible with the depth of (2.0±0.2) mm. The diameter of nylon strand was 0.2 mm, the top of nylon strand was treated by melting paraffin. The interrupted time of blood circulation was 3 hours. Rats in the sham-operation group were treated by slightly drawing back the nylon strand to the CCA immediately after inserting.MAIN OUTCOME MEASURES: ①Neurobehavioral rating: It was conducted at 3 and 12 hours after ischemia with the score ranged 0-4 points.The higher the score was, the severer the neural functional deficit was, 1-3 points signified successful modeling. ②Area of cerebral infarction: Rats wereexecuted at 12 hours after ischemia. Then, brains were quickly removed and stained with tetrazolium chloride (TTC). The percentage of cerebral infarction area was calculated. ③Observation on pathological changes under light microscope.RESULTS: All of 20 rats entered the final analysis.①Eight out of 10 rats in the model group represented contra lateral tumble or draw outward circles, positive Homer's syndrome can be seen in the ligated side (3 points);One rat was disable to completely extend the claws in the contra lateral side of ligation (1 point), one rat had no neural symptoms.②Some pathological changes can be seen in the model group such as swelled cerebral tissues in the ligated side, which were bigger than the contra lateral side and were in pale; The cortex, basal ganglia and thalamus in the ligated side after TTC staining were in pale, whereas the cerebral tissues in the sham-operation group were in red with clear border.③There was no infarct in the sham-operation group, and the percentage of cerebral infarction area in the model group was (22.40±4.52)%, the infarct area of rats in groups were fundamentally same.CONCLUSION: It is necessary to adapt the strand with appropriate diameter, inserted depth and interrupting time for successful modeling.