氯氮平、奥氮平对小鼠在避暗实验中学习记忆获得、巩固和再现过程的影响

Effects of clozapine and olanzapine on acquisition,consolidation and retrieval processes of learning and memory in step-through test in mice

目的:分析抗精神病药氯氮平、奥氮平对避暗实验中小鼠学习记忆的获得、巩固和再现过程的影响。方法:实验于2003-09/2004-01在沈阳药科大学药学院神经药理实验室完成。选择健康雄性昆明种小鼠400只。①自主活动测定方法:取100只小鼠,每50只小鼠随机均分为5组:空白对照组及氯氮平0.1mg/kg组(奥氮平0.01mg/kg组)、氯氮平0.3mg/kg组(奥氮平0.03mg/kg组)、氯氮平1mg/kg组(奥氮平0.1mg/kg组)、氯氮平3mg/kg组(奥氮平0.3mg/kg组)。在测定前,各组分别皮下注射氯氮平、奥氮平或生理盐水(10mL/kg),50min后把小鼠放入自主活动仪中进行自主活动测定,以显示器读数为活动指标,记录10min内小鼠自主活动次数。②避暗实验:训练前将小鼠头背着洞口放入明室,先适应环境3min,然后给暗室铜栅通以36V电流,小鼠一进入暗室即受电击,其正确反应是回到明室,铜栅通电持续5min,此为训练过程。24h后对小鼠进行记忆测验,记录小鼠第一次进入暗室的时间,此为避暗潜伏期,并记录5min内小鼠进入暗室的次数(即避暗错误次数),5min内未进入暗室的小鼠其潜伏期按300s计算。③应用避暗法考察氯氮平与奥氮平对小鼠学习记忆的获得、巩固和再现过程的3个实验中,每个实验100只小鼠,每50只小鼠随机分5组:空白对照组及氯氮平0.1mg/kg组(奥氮平0.01mg/kg组)、氯氮平0.3mg/kg组(奥氮平0.03mg/kg组)、氯氮平1mg/kg组(奥氮平0.1mg/kg组)、阳性药物对照组。训练前50min各组皮下注射受试药物或溶媒,阳性药对照组在训练前10min腹腔注射东莨菪碱3mg/kg,此种给药方案测定小鼠记忆的获得过程;训练后各组立即给予受试药物或溶媒的给药方案为测定记忆的巩固过程,阳性对照组皮下注射亚硝酸钠125mg/kg;测验前50min各组给予受试药物或溶媒的给药方案为测定小鼠记忆的再现过程,阳性对照组在测验前30min灌胃300mL/L乙醇10mL/kg。结果:400只小鼠均进入结果分析。①与空白对照组比较,氯氮平在0.1～1mg/kg剂量范围内,小鼠自主活动无明显变化,而在3mg/kg剂量下,小鼠自主活动明显减少。与空白对照组比较,奥氮平在0.01～0.1mg/kg剂量范围内,小鼠自主活动无明显变化,而在0.3mg/kg剂量下,小鼠自主活动明显减少。因此,在学习记忆的实验中,氯氮平采用0.1～1mg/kg剂量范围,奥氮平采用0.01～0.1mg/kg剂量范围。②与空白对照组比较,训练前给予氯氮平1mg/kg,能明显缩短错误潜伏期[(152.8±36.4)s,(275.5±16.5)s,P<0.01],增加错误次数(1.2±0.3,0.1±0.1,P<0.01)。③训练后或测试前给予氯氮平对小鼠错误潜伏期和错误次数无明显影响。④训练前、训练后或测试前给予奥氮平0.01～0.1mg/kg,对小鼠错误潜伏期和错误次数无明显影响。结论:氯氮平对学习记忆有损伤作用,奥氮平对学习记忆的各个过程基本没有影响。奥氮平对学习记忆的作用优于氯氮平。

AIM： To analyze the effects of clozapine and olanzapine on acquisition, consolidation and retrieval processes of learning and memory in stepthrough test in mice. METHODS： The experiment was carried out in the Laboratory of Neuropharmacology, Shenyang Pharmaceutical University from September 2003 to January 2004. Totally 400 healthy male Kunming mice were used.①Locomotor activity determination： 100 mice were selected, and every 50 mice were randomly divided into 5 groups： blank control group and 0.1 mg/kg clorapine group （0.01 mg/kg olanzapine group）, 0.3 mg/kg clozapine group （0.03 mg/kg olanrapine group）, 1 mg/kg clozapine group （0.1 mg/kg olanrapine group）, 3 mg/kg clozapine group （0.3 mg/kg olanzapine group）. Before determination, the mice in each group were treated with clozapine, olanrapine or saline （10 mL/kg） subcutaneously, respectively. Fifty minutes later the mice were put into a locomotor monitoring cage to measure the locomotor activity. The activity counts of 10 minutes were recorded. ②Stepthrough test： During the training, the mice with the heads contrary to the door were placed in the illuminated compartment and allowed to become adapted for 3 minutes. Then the electric current （36 V） was delivered through the grid floor of the dark compartment for 5 minutes. Once the mouse entered the dark compartment through the door, a scrambled foot shock was delivered. The mice could escape from the shock only by stepping back into the safe illuminated compartment. This was the training section. Twenty-four hours after the training, the response latency to enter the dark compartment at the first time and numbers of errors （enter the dark compartment） in 5 minutes were measured. The latency of not enteri ng the dark room during the 5 minutes was regarded as 300 s. ③In the 3 experiments of observing the effects of clozapine and olanzapine on memory acquisition, consolidation and retrieval processes in step-through test, 100 mice in each experiment were used. Every 50 mice were assigned randomly into 5 groups： blank control group, 0.1 mg/kg clozapine group, （0.01 mg/kg olanrapine group）, 0.3 mg/kg clozapine group （0.03 mk/kg olanzapine group）, 1 mg/kg clozapine group （0.1 mg/kg olanzapine group）, and positive drug control group. Clozapine, olanzapine or vehicle was administered subcutaneously 50 minutes before the training. The 3 mg/kg scopolamine was administered as the positive drug 10 minutes before training for memory acquistition process. Clorapine, olanzapine or vehicle was administered immediately after the training for testing memory consolidation. The 125 mg/kg NaNO2 was administered subcutaneously immediately after training. As the positive drug, clozapine, olanzapine or vehicle was administered 50 minutes before the test for testing memory retrieval. The 10 mL/kg 300 mL/L alcohol was administered by gastric perfusion as the positive drug 30 minutes before the test, RESULTS： Totally 400 mice entered the final analysis.①Compared with the blank control group, there was no significant change in locomotor activity in mice treated with 0,1-1 mg/kg clozapine; The locomotor activity reduced obviously in mice treated with 3 mg/kg clozapine. Compared with the blank control group, there was no significant change in locomotor activity in mice treated with 0.01-0.1 mg/kg olanzapine; The locomotor activity reduced ob- viously in mice treated with 0,3 mg/kg olanzapine, Therefore, 0,1-1 mg/kg clozapine and 0,01-0.1 mg/kg olanzapine were adopted in the step-through test. ②Compared with the blank control group, the latency was significantly shortened [（152.8±36.4） s,（275,5±16.5） s,P 〈 0.01] and the number of errors was significantly increased （1.2±0.3, 0.1±0.1, P 〈 0.01 ） after the ad- ministration of 1 mg/kg clozapine before training.③Clozapine administered did not significantly affect the latency and number of errors after training or before test. ④0.01-0.1 mg/kg olanzapine administered did not significantly affect the latency or number of errors before training, after training or before test. CONCLUSION： Clozapine has impaired effect on learning and memory, while olanzapine does not affect the processes of learning and memory. Olanzapine has better effect on learning and memory than clozapine.