不同持续时间的跑台训练对慢性脑缺血大鼠学习记忆功能的影响

Effects of treadmill training on learning and memory after cerebral ischemia

目的探讨不同持续时间的跑台训练对慢性脑缺血大鼠学习记忆功能的影响。方法将人选的雄性SD大鼠按随机数字表法分为假手术组、模型组和跑台训练组，每组30只，采用双侧颈总动脉永久性结扎法制备脑缺血模型，术后观察3d，造模成功的各组大鼠再根据训练时间的不同又分为7、14和28d三个亚组，每亚组10只。跑台训练的速度为10m／min，斜度0°，训练强度为每日训练30min。跑台训练各亚组分别进行7、14和28d的跑台训练，假手术组和模型组大鼠每日仅固定于跑台训练装置，但不进行跑台训练。采用Morris水迷宫方法检测大鼠的空间学习记忆能力，用尼氏染色法检测大鼠海马CAl区锥体神经元的存活率。结果经跑台训练后，跑台训练组的逃避潜伏期[第7天（43．84±4．98）s、第14天（37．18±2．17）s、第28天（30．72±4．56）s]随着训练时间的延长逐渐缩短（P〈O．05），而其跨越平台的次数[（1．95±0．26）次、（2．05±0．13）次、（2．75±0．26）次]则逐渐增多（P〈0．05）。跑台训练组在训练第14天和第28天时的逃避潜伏期较同时间点的模型组[（48．91±8．52）s和（48．64±7．61）s]明显缩短（P〈0．05），而跨越平台次数较同时间点的模型组[（1．07±0．15）次和（1．25±0．50）次]明显增加（P〈0．05）。尼氏染色发现，假手术组仅可见少量凋亡神经元，训练第14天和第28天时，模型组大鼠的受损神经元较假手术组明显增多，而跑台训练组大鼠的受损神经元数量明显少于模型组大鼠。模型组海马CAl区锥体神经元存活率在第14天亚组和第28天亚组分别为（0．55±0．05）％和（0．50±0．03）％，较同时间点假手术组[（0．77±0．04）％和（0．70±0．02）％]明显降低（P〈0．05）；而跑台训练组的大鼠神经元存活率[（0．62±0．07）％和（0．60±O．07）％]明显高于模型组（P〈0．05）。结论跑台训练14d和28d均可以改善慢性脑缺血大鼠的空间学习记忆能力，跑台训练28d时作用更为显著。

Objective To investigate the effects of exercise on learning and memory after cerebral ischemia. Methods Ninety Sprague-Dawley rats were randomly divided into a sham-operated group, a model group and a treadmill training group （ n = 30 for each） , which were further subdivided into groups to receive 7 days, 14 days or 28 days of training with 10 rats in each. The training was treadmill running at 10 m/rain for 30 rain a day. Cerebral ische- mia was induced in the model and training groups using permanent, bilateral common carotid artery occlusion. The training began three days after the operation. Morris water maze tests were used to measure the rats＇ learning and memory ability, and Nissl staining was employed to detect the survival rates of pyramidal neurons in the CA1 area of the hippocampus. Results The average escape latency in the treadmill trained group had shortened significantly by day 7, then further by days 14 and 28. It was significantly shorter than the model group＇s average at each time point. The average platform crossing time increased significantly compared with the model group＇s average. Few dead neu- rons were observed in the sham-operated group. On days 14 and 28 the average survival rate of pyramidal neurons in the model group was significantly lower than in the treadmill training group or the sham-operated group, though there was no significant difference on day 7. Conclusion Treadmill training can improve learning and memory after cere- bral ischemia, at least in rats. Better effects can be observed after longer training.