The Effect Of Acute Or Chronic Administration Of Escitalopram On Behavior Of Chronic Unpredictable Mild Stress Mice

Objective To investigate the difference of behavior between mice,which suffered from chronic unpredictable mild stress(CUMS),and ones of control group after chronic or acute administration of escitalopram.If the difference between CUMS mice and control group mice was obvious,then it can prepare for our next experiment,which is to investigate diffusion tensor imaging(DTI) of mice,which exposured to CUMS,and ones of control group after acute or chronic administration of escitalopram.Methord According to initial total distance of Open-field test(OFT) for 15min and sucrose preference percentage,some mice were eliminated,60 female C57BL/6 mice were selected and divided into 6 groups randomly on the basis of initial body weight,each group were 10 mice.Control group(naive) were fed for 8 weeks without any management,other 5 groups were all suffered from chronic unpredictable mild stress(CUMS) for 8 weeks as stress groups,including Chronic mild stress group(cms),Acute administration of escitalopram group(cms+Aesc),Acute administration of saline group(cms+Asal),Chronic administration of escitalopram group(cms+Cesc) and Chronic administration of saline group(cms+Csal).After stress of 8 weeks,acute administration of escitalopram was offered twice to cms+Aesc group(12-hour interval between two administrations),acute administration of saline was offered twice to cms+Asal group.During the procedure of stress, from 6^th to 8^th week,cms+Cesc group were administrated escitalopram every day, while cms+Csal group were administrated saline from 6^th to 8^th week every day. During whole process of stress,at 2^nd,4^th,6^th,8^th week,open-field test,sucrose preference test were performed and weight were tested.At 4^th,6^th,8^th week,forced swimming test(FST) was run.(2)After chronic stress for 8 weeks,all mice of 6 groups were performed FMRI.Results(1)Comparing with control group,body weight of all stresss groups were decreased significantly from 2^nd to 8^th week(P<0.01).After chronic administration of escitalopram,the body weight of cms+Cesc group were increased relative to other stresss groups(P<0.01),which yet were lighter than control group(P<0.01).(2)In open-field test for 15min,the total distance and central distance of stresss goups were further,and numbers of rear were more than control goup(P<0.05) from 2^nd to 4^th week,but then these indexes were decreased from 6^th to 8^th week(P<0.05).After administration,the total distance,central distance and numbers of rear of cms+Cesc group raised,but also not attain to the level of control group.At same condition,the total distance and numbers of rear of cms+Csal group were diminished compared with other stresss groups.(3)In sucrose preference test,the preference percentage for sucrose of stresss groups decreased(P<0.05) relative to control group from 6^th to 8^th week,at 8^th week,the preference percentage of cms+Cesc group increased compared with other stresss groups(P<0.05),but the index of cms+Csal group was reduced (P<0.05).(4)In forced swimming test,compared with control group,immobility time of stresss groups growed from 4^th to 8^th week.After chronic administration, immobility time of cms+Cesc group was less than other stresss groups,but was more than control group.Immobility time of cms+Csal group was more than other stress groups under same circumstances.(5)After acute administration of escitalopram,the behavior of cms+Aesc group was no difference relative to pure cms group.Conclusion:(1)After exposuring to cums,mice displayed the symptom of depression, that is,the body weight,activity ability and exploratory ability decreased,the immobility time in FST was increased.(2)Chronic administration of escitalopram can improve the body weight,boost sucrose preference percentage and activity ability in open-field test,and can reduce the immobility time in FST,that is,chronic administration show up efficacy on depression,but acute administration have no efficacy.