摘要
目的:观察慢性应激状态下大鼠学习能力和决策行为的变化。方法:实验于2005-07/12在青岛大学医学院附属医院脑病防治重点实验室完成。成年健康雌性Wistar大鼠32只,随机抽签法分为慢性应激组和对照组,每组16只。其中8只用于学习能力测试,另8只用于决策行为测试。慢性应激主要按照Moreau和Froger等的方法进行。主要有:①冷水游泳,30min/次。②束缚大鼠四肢,3h/次。③每周各2次食物剥夺12h。④饮水剥夺14h。⑤彻夜光照14h。⑥湿笼饲养14h。每周随机交替进行,共4周。大鼠学习能力参照文献方法进行,采用MG-2型迷宫刺激器,将大鼠放入迷宫箱后予以电击,至其逃避至安全区为止。规定大鼠逃避至安全区为正确反应,否则为错误反应,休息1min后再进行第2次测试,依次重复。直到大鼠连续10次测试中有9次正确反应为止,记录其所需要的电击次数,作为学习成绩。决策行为观察主要参照Froger和Pardon等方法进行。所用设备包含3个等长的臂,离地面高1m,中间和右侧臂有透明的臂和底是安全的,左侧臂悬浮在地面上空开,有潜在的不安全性。行为范式是进行两个相隔10s的行为测试实验。第一个实验只探索安全臂,另一个臂被门阻挡,动物放在开始的盒子里,10s后到中心路径的门被打开,当大鼠将四肢放在目标盒子里,本次试验被认为完成,无时间限制。第二个实验,大鼠在目标盒子里限制5s后,移走并且放在开始的盒子里,10s后,门被打开,可自由接近两个臂,当大鼠将四肢放入两个目标臂中的任何一个,或者时间超过5min,则认为实验完成。在两个实验中,开始打开门到关闭门的时间犤解决任务的时间犦最长限定为5min。各进行50次实验。结果:16只大鼠均进入结果分析。①学习能力方面:慢性应激组大鼠迷宫电击次数(学习成绩)比对照组显著增多犤(40.52±5.49),(26.37±6.75)次,t=4.60,P<0.01犦。②决策能力方面:慢性应激组大鼠的选择次数与对照组差异无显著性意义犤(15.7±2.8),(15.2±2.1)次,t=0.40,P>0.05犦;慢性应激组回避次数比对照组显著增多犤(30.6±5.2),(21.3±4.5)次,t=3.83,P<0.01犦;无选择次数比对照组显著减少犤(5.5±2.1),(15.4±3.8)次,t=6.43,P<0.01犦;慢性应激组大鼠两个实验解决任务的时间均比对照组显著减少犤实验1:(59.7±6.2),(105.5±11.8)s,t=6.55,P<0.01犦;犤实验2:(46.9±9.2),(112.8±13.5)s,t=11.4,P<0.01犦。结论:慢性应激可导致大鼠学习能力显著下降,决策能力损伤。慢性应激可能导致大鼠大脑发生相应的病理改变。
AIM： To observe the changes in abilities of learning and decision-making of rats with chronic mild stress （CMS）. METHODS： The experiment was conducted in the Key Laboratory of Cerebrovascular Disease, Affiliated Hospital of Medical College of Qingdao University from July to December 2005. Thirty-two healthy male adult rats were randomly divided into two groups： CMS group and control group with 16 rats in each group. Eight rats were used to test the capacity of learning, while another 8 rats were tested of the ability of decision-making. Rats with CMS were treated mainly by Moreau and Froger methods, including： ① Cold water swimming, and 30 minutes each time. ② Chronic immobilization stress （3 hours per time）. ③ Rats were deprived of the food twice each week and 12 hours each time. ④ Deprivation of water for 14 hours. ⑤Rats were exposed to illumination day and night for 14 hours.⑥ Rats were raised in wet coop for 14 hours. These stressors were conducted in random alernation for totally 4 weeks. MG-2 maze stimulator was adopted, and electrical shock was conducted on rats until they escaped to safe area. Rats＇ escaping to safe area was considered as correct response, otherwise was wrong response. The second trial was conducted at one minute after resting, and trials were repeated. Trials were continued until 9 out of 10 continuous trials were correct responses, and the shocking times that needed were recorded and taken as the learning records. Observation on decision-making was conducted by referring to Pardon and Froger methods. The apparatus was consisted of three arms of equal dimensions, which was 1 m high from the floor. The central path and the right arm were ＂secure＂, and the left arm was considered to be potentially ？insecure＂, which was suspended in the open above the floor, with several openings through the walls and no roof. The behavioral paradigm was consisted of two trials with an interval of 10 s. In the first trial, rats were forced to explore the ＂secure＂ arm with the other arm being blocked by the door. To begin the forced-reference trial, rats were placed in the starting box, and the door to the central path was opened at 10 s later. The trial was considered to be completed when all four legs of rats were inside the goal box, and there was no time limit. Rats were limited for 5 s in the goal box and then removed and being placed in the starting box for the test trial. Ten seconds later, the door was opened, and rats were able to get access to both arms. The trial was considered to be completed when either of rat＇s four legs was in one of the two goal boxes or the time exceeded 5 minutes. In both trials, the maximum time from door-opening to door-closing （time of executing tasks） was limited to 5 minutes. Fifty tests was conducted respectively in both trials. RESULTS： A total of 16 rats were involved in the analysis of resuhs.①In learning ability, the shocking times （learning records） of rats in the CMS group was significantly increased than that in the control group [（40.52 ±5.49）, （26.37±6.75）times,t=4.60, P 〈 0.01].② Decision-making ability： there was no significant difference in times of alternation between the two groups [（15.7±2.8）, （15.2±2.1） times, t=0.40,P 〉 0.05], but the times of avoidance in the CMS group were remarkably more than that in the control group [（30.6±5.2）, （21.3±4.5） times, t=3.83, P 〈 0.01]. The times of no choice in the CMS group was obviously less than that in the control group [（5.5±2.1）, （15.4 ±3.8） times, t=6.43,P 〈 0.01]. The time of solving problem in both trials was obviously less in the CMS group than that in the control group [First trial （59.7±6.2）, （105.5±11.8） s, t=6.55, P 〈 0.01]. [Second trial （46.9±9.2）, （112.8±13.5） s, t=11.4,P 〈 0.01]. CONCLUSION： CMS can cause significant decrease of learning ability and damage in ability of decision-making in rats, which might result in the pathological changes of rat＇s brain.
出处
《中国临床康复》
CSCD
北大核心
2006年第34期103-105,共3页
Chinese Journal of Clinical Rehabilitation
基金
山东省科技厅科研基金资助项目(003130110
22130109)~~
