Memory Impairment And Expression Of ERK5 In Hippocampus Of Rats With Post-traumatic Stress Disorder

Part?Correlation between memory impairment and differential expressionof ERK5 in hippocampus of PTSD-like rats ObjectiveTo investigate the relationship between memory impairment and the expression of extracellular signal-regulated kinase 5(ERK5)in hippocampus of rats with post-traumatic stress disorder(PTSD).MethodsForty SD rats were randomly divided into 5 groups: Control group,PTSD 1d group,PTSD 3d group,PTSD 7d group and PTSD 14 d group,with 8 rats in each group.The PTSD-like model were established using the internationally recognized single-prolonged stress & foot shock stimulation(SPS&S).On the first,third,seventh and fourteenth days after modeling the open field experiment was performed in the PTSD 1,3,7 and 14 d groups of rats(Control group and PTSD 14 d group together,the same below),respectively.On the second,fourth,eighth and fifteenth days after modeling the Morris water maze experiment was carried out for 5 consecutive days in PTSD 1,3,7 and 14 d groups of rats,respectively,which could measure the spatial exploration ability of each group.On the sixth day,the platform was removed and the spatial memory ability of the rats was measured.The hippocampus tissues of rats in the PTSD 1,3,7 and 14 d groups were extracted on the 8th,10 th,14th and 21 st day after modeling,and the Reverse Transcription Polymerase Chain Reaction(RT-PCR)and Western blot were adopted to detect the changes of ERK5 m RNA expression and protein levels in hippocampus of each group.Results1.In the open field experiment,compared with the Control group,the number of standing and cross-grid times of the PTSD 7d and 14 d groups were decreased(P<0.05);in the Morris water maze test,compared with the Control group,on the 4th and 5th day,the escape latency of rats in the PTSD 7d and 14 d groups was prolonged.On the 6th day,the incubation period of the first time crossing the platform was prolonged and the number of crossing was reduced(P<0.05).2.RT-PCR and Western blot showed that compared with Control group,the m RNA expression and protein level of ERK5 in hippocampus of PTSD 7d and 14 d groups were significantly increased(P<0.05).ConclusionsAfter SPS&S,the learning and memory ability of PTSD-like rats were decreased,and the expression of ERK5 in hippocampus was increased,but it does not happen immediately.Part?Effects of agomelatine on memory impairment and expression ofERK5 in hippocampus of PTSD-like rats ObjectiveTo investigate the effect of Agomelatine on memory impairment and the expression of ERK5 in hippocampus of PTSD-like rats.MethodsForty-eight SD rats were randomly divided into control group(SHAM group),post-traumatic stress disorder group(PTSD group),agomelatine group(AGO group)and placebo control group(PC group)with 12 in each group.The PTSD-like model of the latter three groups was established by SPS&S,and the AGO group and PC group were given the same amount of agomelatine and saline respectively by intragastric administration within 6 hours after modeling for 14 days.The fear behavior,arousal emotional level and learning and memory ability of rats were observed by the electric shock box experiment,Open Field experiment and Morris water maze test.Then the m RNA expressions and protein levels of ERK5 in hippocampus of rats were detected by RT-PCR and Western blot.Results1.In the electric shock box experiment,the stagnant time of the AGO group was shorter than that of the PC group(P<0.05);In the open field experiment,compared with the PC group,the number of standing and crossing in the AGO group were increased(P<0.05);in the navigation stage of the Morris water maze experiment,the escape latency of the AGO group was shorter than that of the PC group.In the space exploration experiment stage,compared with the PC group,the number of crossing in the AGO group were increased,and the incubation period of the first time crossing the platform was shortened(P<0.05).2.RT-PCR and Western blot showed that compared with SHAM group,the m RNA expression and protein level of ERK5 in hippocampus of PTSD group were significantly increased.Compared with PC group,the m RNA expression and protein level of ERK5 in hippocampus of AGO group were increased(Both P<0.05).ConclusionsAgomelatine can effectively improve the learning and memory ability of PTSD-like rats,which may be related to the up-regulation of ERK5 expression in hippocampus.ERK5 may be act as a protective factor in the repairment of memory impairment of PTSD-like rats.