慢性复合应激增强大鼠空间学习和记忆能力

本文观察了慢性复合应激对大鼠学习与记忆功能的影响。实验采用成年 Wistar 大鼠, 将其随机分成应激组和对照组。采用垂直旋转、睡眠剥夺、噪音刺激和夜间光照4 种应激原, 无规律地交替刺激动物 6 周, 每天6 h, 制作慢性复合应激动物模型。采用 Morris 水迷宫和 Y- 迷宫测试大鼠学习与记忆成绩,并用 Cresyl violet 染色法对大鼠海马结构进行神经细胞计数。结果显示,应激组动物慢性复合应激后, 在 Morris 水迷宫内寻找隐蔽平台所需的时间(潜伏期)比对照组的明显地短(P<0.05), 表明应激鼠的空间记忆能力明显强于对照鼠;在 Y- 迷宫内寻找安全区的正确率比对照组的明显地高(P<0.05), 表明应激鼠的明暗分辨学习能力明显强于对照鼠; 应激鼠慢性复合应激后, 其海马结构齿状回、CA3 和CA1 区神经细胞密度极明显地高于对照鼠(P<0.001)。这些结果提示, 慢性复合应激可增强大鼠空间记忆能力和明暗分辨学习能力。本文并对慢性复合应激模式增强大鼠学习和记忆能力的可能原因进行了讨论。

Chronic multiple stress enhances learning and memory capability in rats

The present study aimed at investigating the effects of chronic multiple stress on learning and memory functions of rats. Adult male Wistar rats were randomly divided into stressed and control groups. Rats in the stressed group were irregularly and alternately exposed to the situation of vertical revolution, sleep deprivation, noise stimulation, and night illumination 6 h per day for 6 weeks to prepare a chronic multiple stressed model. Learning and memory performance of rats was measured by using Morris water maze first and Y-maze afterwards. Neurons in the dentate gyrus(DG), CA3 and CA1 regions of the hippocampus were stained by using Cresyl violet method and counted. The results showed that: (1) After chronic multiple stress, compared with the control rats, the escape latency to the hidden platform in Morris water maze was significantly shortened in stressed rats. In stressed and control groups, the escape latency periods were (15.89+/-9.15) s and (27.30+/-12.51) s, respectively, indicating that spatial memory of the stressed rats was stronger than that of the control ones. In brightness-darkness discrimination learning in the Y- maze, the correct trials and correct percentage of entering safe arm was remarkably increased in the stressed rats, the correct rates of stressed and control groups were (79.01+/-1.23)% and (66.12+/-1.61)%, respectively, indicating that brightness-darkness discrimination learning ability of the stressed rats was better than that of the control ones. (2) After chronic multiple stress, nerve cell density in DG, CA1 and CA3 of the hippocampus in stressed rats was higher than that of the control group, the cell densities in DG, CA1 and CA3 of the stressed and the control group were (223.78+/-26.52), (112.07+/-14.23) and (105.55+/-18.12) as well as (199.13+/-15.36), (92.89+/-13.69), and (89.02+/-15.77) respectively. These results suggest that the chronic multiple stress may enhance the capability of spatial memory and brightness-darkness discrimination learning of rats. Possible reasons for the chronic multiple stress-induced learning and memory enhancement of rats were also discussed.