慢性强迫游泳与限制应激对大鼠学习记忆能力影响的比较

目的 研究慢性强迫游泳应激和低强度长时间慢性限制应激对大鼠空间学习记忆能力的影响.方法 24只健康成年雄性SD大鼠随机分为对照组(CONTROL):正常饲养14d;强迫游泳组(FST):每天进行20min强迫游泳,连续14d;限制组(CRS):每天进行6h限制,连续14d.利用Morris水迷宫的定位航行实验和空间探索实验分别评估大鼠的空间学习和记忆能力.结果 (1)应激结束后第1,2周的定位航行实验中,FST大鼠的上台潜伏期显著缩短[第1周FST组第4,5次(14.56±2.17)s,(17.93±2.08)s、CONTROL组(26.12±5.04)s,(25.22±2.80)s,t=11.21和7.25,均P＜0.05],同时,应激结束后的空间探索实验中,FST大鼠在目标象限活动时间的百分比显著高于CONTROL组(P＜0.05).应激结束后第3周,FST组和CONTROL组大鼠的上台潜伏期、目标象限活动时间百分比与CONTROL组相比较差异无显著性.(2)应激结束后的定位航行实验中,CRS组大鼠的上台潜伏期长于CONTROL(P＜0.05);同时在空间探索实验中,CRS组在目标象限的活动时间百分比显著低于CONTROL组(P＜0.05),应激结束后第2,3周2组则差异无显著性.结论 慢性强迫游泳增强大鼠的空间学习和记忆能力,这种效应持续时间较长;而低强度慢性限制损害大鼠的空间记忆能力,这种效应持续时间较短.

Different effects of chronic forced swim and restraint stress upon the rat spatial learning and memory

Objective To observe the effect of chronic forced swim or restraint stress on the rat's spatial learning and memory performance.Methods Twenty-four adult male Sprague-Dawley rats were randomly divided into three groups:control group(rats receiving neither stress);chronic forced swim stress (FST) group(rats were forced to swim daily for 20 minutes during 14 days);and chronic restraint stress (CRS) group(rats were loosely restrained daily in a transparent plastic cylinder which made the rats could not move freely for 6 hours during 14 days).1,2 or 3 weeks after the final secession of either stress,the navigation test and probe test of Morris water maze were employed to evaluate the rat's spatial learning and memory ability,respectively.Results (1) 1 and 2 weeks after the final stress secession,the averaged escape latency of FST group in the navigation test was significantly shortened [1week:FST (14.56±2.17)s,(17.93±2.08)s,CONTROL(26.12±5.04)s,(25.22±2.80)s,t=11.21 and 7.25,P＜0.05];meanwhile,the averaged ratio of time spent in the target quadrant for the FST group in the probe test was significantly higher than that of the control group(P＜0.05).3 weeks after the final stress secession,there was no significant difference in the escape latencies and the ratio of time spent in the target quadrant between control and FST group.(2) 1 week after the final stress secession,both the averaged escape latency in the navigation test and the averaged ratio of time spent in the target quadrant for the probe test of CRS group were significantly changed when compared with that of the control group (P＜0.05).While 2 or 3 weeks after the final stress secession,these differences disappeared.Conclusion Chronic forced swim enhanced while the chronic low intensity restrain impaired rat's spatial learning and memory.These effects could not last long since the difference disappeared as the rats withdrew from the stress for a relatively long period.Different patterns of chronic stress gave rise to different reversible influences upon the rat's spatial learning and memory.