慢性强迫游泳后大鼠焦虑抑郁行为及空间学习记忆能力的动态变化

目的 探讨长期强迫游泳后大鼠焦虑抑郁行为以及空间学习和记忆能力的动态变化.方法 将24只成年雄性SD大鼠随机分为对照组(CONTROL组)及强迫游泳组(FST组),利用MORRIS水迷宫来测定大鼠的空间学习和记忆能力,其中在应激结束后第1,7,14,21天进行大鼠空间学习能力,第2,8,15,22天进行大鼠记忆能力测试,旷场、高架十字迷宫来测定大鼠的焦虑抑郁行为.结果 (1)MORRIS水迷宫实验:定位航行训练中,应激结束后第1天的第4,5组实验的上台潜伏期[(12.57±2.17)s;(14.56±2.17)s]低于CONTROL组大鼠[(29.13±5.04)s;(26.13±5.04)s](P<0.05);第7天FaT组大鼠的第1,3组实验的上台潜伏期[(16.88±2.82)s;(13.33±1.57)s]低于CONTROL组大鼠[(35.04±4.53)s;(23.66±4.04)s],差异有显著性(P<0.05).空间探索试验中,应激结束后第2天和第8天FST组在目标象限游泳时间的百分比和穿台次数显著高于CONTROL组(第2,8天均为P<0.05).在应激结束3周后,CONTROL组和FST组大鼠的上台潜伏期和目标象限游泳时间的百分比以及穿台次数均差异无显著性(P0.05).(2)高架十字迷宫实验:第1次P3T后大鼠的开臂停留时间[(2.48±2.22)s]显著短于CONTROL组[(40.82±8.33)s],差异有显著性(P<0.05);同时开臂进入次数也显著少于CONTROL组(P<0.05),这种差异持续到应激结束后第1天.应激结束7d后2组的开臂停留时间和进入次数已经基本一致.(3)旷场实验:应激结束后第1天和第7天的FST组大鼠的水平活动度和活动次数均显著少于CONTROL组(P<0.05).结论 慢性强迫游泳可以提高大鼠短期的空间学习、记忆,但并不影响大鼠长期的空间学习、记忆能力;可以使动物产生焦虑抑郁样行为但并不稳定.

The temporal change of the anxiety and depression like behaviors and spatial learning and memory of rats forced swimming test

Objective To observe the temporal change of the anxiety and depression like behaviors and spatial learning and memory of rats receiving repeated daily forced swimming test (FST). Methods Twenty-four adult male Sprague-Dawley rats were randomly divided into CONTROL group and forced swimming test (FST) group. The rats in FST group were given 14 repeated daily FST when the rats were forced to swim for 20 min. The spatial learning and spatial memory were tested using a Morris Water Maze (MWM) weekly. The spatial learning ability was evaluated with the averaged escape latencies to the plate. The consolidation of spatial memory was eval- uated by the ratio of time spent in the target quadrant and number of crossing the plate in the probe test. Open field (OF) and the elevated plus maze (EPM) were employed to detect the anxiety/depression like behaviors. Results (1) The group4 and5 at 1 day [(12.57±2.17)s; (14.56±2.17)s] the escape latencies of rats in FST group were significantly lower than those of CONTROL group [(29.13±5.04)s; (26.13±5.04)s] (P< 0.05); The group 1 and 3 at 7 day after the 14 FST sessions,the escape latencies of rats in FST group were signif- icantly lower than those of CONTROL group [(35.04±4.53)s; (23.66±4.04)s](P<0.05). The ratio of time spent in the target quadrant of FST group at day 2 day 8 after 14 daily FST were significantly higher than CON- TROL group(P<0.05). (2) The number of entering the open- arm and the open-ann detention time[(2.48± 2.22)s] in the elevated plus maze after the first FST were significantly lower than CONTROL group [(40.82± 8.33)s] (P<0.05). (3) In the Open field Test, one day after 14 repeated FST, the horizontal distance and ac- tive times of FST group were lower than those of the control group (P<0.05). Seven day after 14 repeated FST, the horizontal distance and active times of FST group were also lower than those of the control group (P<0.05). Conclusion After being forced to swim for 14 days the rats demonstrated some anxiety/depression like behaviors which can not be observed after 3 weeks. Different indexes of behavior have different sensitive periods.