【摘要】 目的:通过反复低血压及双侧颈总动脉阻断后建立血管性痴呆大鼠模型,观察大鼠学习记忆能力和脑组织病理学变化。方法:实验于1999-09/2000-01在重庆医科大学第一附属医院神经病学研究所完成。选择健康雄性Wistar大鼠30只,随机分3组,假手术组10只、反复脑缺血后2周组10只、反复脑缺血后12周组10只。采用反复股动脉抽血/回输(25mL/kg)和双侧颈总动脉阻断(10min)法建立血管性痴呆大鼠模型。进行跳台试验时,让大鼠在箱内适应5min后再放到平台(安全区)上并通电,记录大鼠第1次步下平台的时间,即潜伏期,及5min内大鼠步下平台被电击的次数,即错误次数。24h和48h后重复上述试验,但一开始即将大鼠放到平台上并通电。然后进行穿梭箱试验,其参数设置为:蜂鸣(条件刺激)时间5s,电刺激(非条件刺激)时间20s,电流强度3mA,间隔30s,循环20次。即给予声刺激(蜂鸣)5s,期间如大鼠(主动)逃避到箱的另一端,蜂鸣停止并转为间隔期,否则给予电击;电击期间如大鼠逃避到箱的另一端,电击停止并转为间隔期,否则持续被电击20s;间隔30s后又给予声刺激,重复20次为1个循环。计算机自动控制并记录大鼠在1个循环中被电击次数、被电击时间和主动逃避时间。每天1个循环(箱内适应5min后开始),连续5d。常规苏木精-伊红染色,甲酚紫/酸性品红染色观察脑组织病理学变化。结果:纳入动物30只,实验过程中死亡6只,进入结果分析24只。①跳台试验结果:与假手术组比较反复脑缺血后2周组和反复脑缺血后12周组的错误次数明显增多[以第3天为例,假手术组、反复脑缺血后2周组、反复脑缺血后12周组分别为(1.3±1.0),(9.2±2.0),(12.9±2.3)次,P<0.01],潜伏期显著缩短[以第3天为例,假手术组、反复脑缺血后2周组、反复脑缺血后12周组分别为(193.6±68.9),(20.3±8.2),(12.0±4.4)s,P<0.01]。②程控穿梭箱试验结果:第5天与假手术组比较反复脑缺血后2周组和反复脑缺血后12周组在1个循环中被电击次数明显增多[假手术组、反复脑缺血后2周组、反复脑缺血后12周组分别为(5.5±1.2),(14.2±2.6),(17.7±2.6)次,P<0.01],被电击时间明显增多[假手术组、反复脑缺血后2周组、反复脑缺血后12周组分别为(19.3±8.1),(129.2±23.4),(178.2±35.5)s,P<0.01],主动逃避时间明显减少[假手术组、反复脑缺血后2周组、反复脑缺血后12周组分别为(38.2±6.8),(11.2±5.0),(3.4±3.1)s,P<0.01]。③脑组织神经元改变结果:术后2周大鼠出现明显的学习和记忆障碍,大脑皮质、海马CA1和CA4区神经元丢失分别为29.8%,92.1%,24.4%,但无明显的肢体瘫痪;12周后大鼠学习和记忆障碍进一步加重,大脑皮质、海马CA1和CA4区神经元丢失分别为35.8%,94.0%,30.2%,但脑损害无明显加重。结论:反复低血压及双侧颈总动脉阻断法能高度模拟血管性痴呆的临床特点,是一种可靠、简易而实用的血管性痴呆大鼠模型。更多还原

【Abstract】 AIM: To induce rat models of vascular dementia induced by repeated hypotension in combination with occlusion of bilateral common carotid arteries, and observe the changes of learning and memory abilities and the pathological changes of brain tissue.METHODS: The experiment was carried out in the Institute of Neurology, the First Affiliated Hospital of Chongqing University of Medical Sciences between September 1999 and January 2000. Thirty healthy male Wistar rats were randomly divided into 3 groups: sham-operated group (n=10), 2 weeks after repeated cerebral ischemia group (n=10) and 12 weeks after repeated cerebral ischemia group (n=10). Rat models of vascular dementia were induced by repeated withdrawal/recirculation (25 mL/kg) of femoral artery in combination with occlusion of bilateral common carotid arteries (10 minutes). For the jumping stand test, the rats were place on the platform (safe region) and connected with electricity after adaptation for 5 minutes in the body, the time for the rats to step from the platform for the first time (latency) was recorded, the number of times for the rats to step from the platform and to be shocked within 5 minutes (number of mistake times) was also recorded. The above test was repeated after 24 and 48 hours respectively, but the rats were placed on the platform and connected with electricity immediately at the beginning. The shuttle box test was also performed, the indexes were set as that 5 s for sinning (conditional stimulation), 20 s for electric stimulation (non-conditional stimulation), the current intensity was 3 mA, which were cycled for 20 times with an interval of 30 s. Sound stimulation (singing) was given for 5 minutes, and if the rats escaped (actively) to the other end of the box, the singing would be stopped and entered the interval; otherwise, shock would be given. During shocking, if the rats escaped to the other end of the box, shock would be stopped and entered the interval; otherwise, shock would last for 20 minutes, and followed by sound stimulation after an interval of 30 s, which were repeated for 20 times as a circle. The number of being shocked, duration of being shocked and time of active escape in one circle for the rats were automatically controlled and recorded by computer. There was one circle every day (began after adaptation for 5 minutes in the box) for 5 continuous days. The pathological changes of brain tissue were observed by haematine-eosin (HE) staining and cresol purple/acid fuchsin staining.RESULTS: Totally 30 rats were used, and 6 died during the experiment, finally 24 rats entered the analysis of results. ① Results of the jumping stand test: As compared with the sham-operated group, the numbers of mistake times in the 2 and 12 weeks after repeated cerebral ischemia groups were obviously increased on the 3rd day: (1.3±1.0), (9.2±2.0), (12.9±2.3) times, P < 0.01 , and the latencies were significantly shortened on the 3rd day: (193.6±68.9), (20.3±8.2), (12.0±4.4) s, P < 0.01 . ② Results of the shuttle box test: On the 5th day as compared with the sham-operated group, the number of shocked times in one circle in the 2 and 12 weeks after repeated cerebral ischemia groups were obviously increased (5.5±1.2), (14.2±2.6), (17.7±2.6) times, P < 0.01 , the durations of being shocked were obviously increased (19.3±8.1), (129.2±23.4), (178.2±35.5) s, P < 0.01 , and the times of active escape were markedly reduced (38.2±6.8), (11.2±5.0), (3.4±3.1) s, P < 0.01 . ③ Neuronal changes of brain tissue: At 2 weeks postoperatively, obvious learning and memory disorders occurred in the rats, the neuronal loss in cortex and hippocampal CA1 and CA4 were 29.8%, 92.1% and 24.4% respectively, but there was no obvious palsy of limbs. At 12 weeks postoperatively, the learning and memory disorders were aggravated, and the neuronal loss in cortex and hippocampal CA1 and CA4 were 35.8%, 94.0% and 30.2% respectively, but the brain damage had no obvious aggravations. CONCLUSION: Repeated hypotension in combination with occlusion of bilateral common carotid arteries in rats could highly mimic the clinical features of vascular dementia, which might be a reliable, simple and useful rat model of vascular dementia.更多还原