| Fear is a basic emotion closely related to evolution,which can stimulate a series of defense mechanisms,and plays an important role in human survival and adaptation.The fear memory formed by excessive fear is the important reason of mental illness,so it is necessary to understand and intervene the fear memory.Fear regression is the most common model for the study of traumatic stress disorder.Selective serotonin reuptake inhibitors(SSRIs)are currently used in the treatment of post traumatic stress disorder(PTSD).Escitalopram(ESCI),as a high-efficiency drug for selective serotonin reuptake inhibitors,is thought to regulate fear memory.In this study,C57BL/6 was used as the research object,and the scene conditioned fear memory was acquired by training animals to explore the behavioral characteristics of different time-varying fear memory.On this basis,the regulatory effect of escitalopram on the conditioned fear memory in different time periods was explored.This study is divided into three experiments.The main purpose of the experiment was to investigate whether the treatment of escitalopram could promote the elimination of conditioned fear memory in mice and alleviate the acquired anxiety symptoms.The first day of the experiment was conducted to train the mice with the condition of fear(D1),3 days(D3),7 days(D7),14 days(D14),21 days(D21)and 35 days(D35)respectively.The regression was divided into two stages(extinction 1 and extinction 2),each stage exposed the mice to the fear training environment for 15 minutes,and the interval between the two retreats was 24 hours.The test of extinction memory was carried out 24 hours after the retreat training,and then the spontaneous recovery test was investigated 2 weeks later.Based on the results of Experiment 1,three different time histories were selected for ESCI intervention in experiment two and three experiments.The three time histories of fear memory were short-term(D1),medium time(D7)and long-term(D21)escitalopram.In the second experiment,mice were given subcutaneous injection of escitalopram(lmg/kg,5mg/kg)once on the first day of the experiment,and then the fear conditioned training(Train)was conducted 30 minutes after the drug injection,and then the fear memory was eliminated at 1 day,7 days(D7)and 21 days(D21).The regression was divided into two stages(Extinction 1 and Extinction 2),each stage exposed the mice to the fear training environment for 15 minutes,and the interval between the two retreats was 24 hours.The test of extinction memory was carried out 24 hours after the retreat training,and then the spontaneous recovery test was investigated 2 weeks later.In the third day,the mice were given the first day of the experiment with D1,train,and then gave mice subcutaneous injection of escitalopram(1mg/kg,5mg/kg),once after the injection of drugs for 30 minutes,and then the fear memory was eliminated after 30 minutes after the drug injection.The regression was divided into two stages(Extinction 1 and Extinction 2),each stage exposed the mice to the fear training environment for 15 minutes,and the interval between the two retreats was 24 hours.The test of extinction memory was carried out 24 hours after the retreat training,and then the spontaneous recovery test was investigated 2 weeks later.Research findings:(1)There was no significant difference in the expression level of fear memory in different memory time after scene fear training.During the process of retreat,long-term fear memory was difficult to fade.(2)Before training,the drug of 5mg/kg could significantly reduce the fear acquisition,and the group of the drug administration could promote the elimination of long-term fear memory.(3)The effect of escitalopram before the withdrawal was better than that of the ESCI group,and the long-term fear memory was decreased in the 5mg/kg ESCI group.Research shows:Escitalopram can reduce the conditional fear memory in the scene,and high dose can promote the decline of long-term fear memory,and no spontaneous recovery. |
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