利用正交试验优化建立大鼠条件恐惧记忆模型

Optimization of a rat model of conditioned fear memory using an orthogonal design

目的 利用正交试验,优化建立大鼠条件恐惧记忆模型的最佳实验参数,寻找最佳试验条件。方法利用巴普洛夫条件恐惧原理,建立大鼠条件恐惧记忆模型;采用3因素3水平的正交试验设计,以模型建立24h后大鼠木僵反应时间为指标,观察不同参数条件下恐惧记忆的表达情况,确定最佳试验条件。以优选的实验条件建立条件恐惧记忆模型,并于24h、1周、2周、4周和8周后进行恐惧记忆保持检测。结果 直观分析结果表明,各因素影响能力依次为声音强度=循环次数>电击强度;方差分析结果表明,循环次数对实验结果有显著影响(P<0.05),声音强度和电击强度影响不显著(P>0.05)。确定最优实验条件为:声音75dB,电击0.8mA,循环15次。在模型建立24h和1周时,大鼠恐惧记忆保持良好,与对照组比较差异有显著性(P<0.001和P<0.05);第2周后恐惧记忆逐渐消退,与对照组比较差异无显著性(P>0.05)。结论 本实验明确了大鼠条件恐惧记忆模型影响因素的主次,优化了实验条件,为模型的标准化、规范化及后续研究提供了可借鉴的实验的依据。

Objective An orthogonal design was used to optimize the experimental parameters for the establishment of a rat model of conditioned fear memory and to identify the optimal experimental conditions.Methods The model of conditioned fear memory in rats was established based on pavlovian conditioned fear theory.Three factors,namely sound intensity,cycle times and electric shock intensity,were adopted,and each factor was set at 3 levels.Orthogonal test was carried out,and the freezing time ratio of rat was taken as the index to observe the changes in different parameters of expression of fear memory and determine the best experimental conditions.The conditioned fear memory model was established again under the optimal conditions of the previous experiment,and the fear memory retention test was conducted 24 h,1 week,2 weeks,4 weeks and 8 weeks later.The rats without fear training were used as the control group.Results The intuitive analysis results showed that the effects of various factors on the duration of fear memory of rats was sound intensity=cycle times>electric shock intensity in turn.The ANOVA test showed that the cycle times had a significant impact on freezing time ratio(P<0.05),but the sound intensity and electric shock intensity had no significant impact(P>0.05).The optimal experimental conditions were as follows:75 dB sound,0.8 mA electric shock,and 15 cycles.Fear memory was maintained at 24 h and 1 week after the establishment of the model,which was significantly different from that of the control group(P<0.001 and P<0.05).Fear memory had faded 2 weeks later,at which point there was no significant difference in freezing time ratio between the model and control groups(P>0.05).Conclusions This experiment clarifies the primary and secondary factors that influence the establishment of a rat model of conditioned fear memory The optimal experimental method for model establishment are identified.This study lays a foundation for the standardization and normalization of fear memory model.