Effects Of Post Stroke Mild Stress On Hippocampal Sur1 Expressed In Rats

BackgroundPost stroke depression(PSD)is a particularly frequent neuropsychiatric disorder,which occurs in approximately one-third of stroke survivors and has been associated with increased morbidity and mortality,poorer stroke-related outcomes including significant social and cognitive impairment.Sur1 and Kir formated KATP channel,which involved in nerve functional recovery after cerebral ischemia.Chronic mild stress may influence Sur1 expression,which may be associated with BDNF expression and congnitive alteration.The aim of this study was to observe the effect of chronic stimulation on the behavioral level and the expression of Sur1,Kir6.1,Kir6.2 and BDNF mRNA in stroke rats,and to explore the role of Sur1,Kir6.1,Kir6.2 and BDNF in the process of post-stroke depression and its mechanism.Objectives1.To observe the levels of Sur1,Kir6.1,Kir6.2 and BDNF mRNA in hippocampus of stroke rats and to study whether Sur1 and Kir6.x are associated with cognitive impairment in rats.2.To make clear the effect of chronic stimulation on depressive state and cognitive function of stroke rats and investigate whether Sur1 influence congnitive function via regulating BDNF expression.Methods1.Normal SD rats were randomly divided into normal group,chronic unpredictable mild stress(CUMS)group,middle cerebral artery occlusion(MCAO)group.The CUMS group and the normal group were treated with sham operation.The rat model of focal cerebral ischemia was established by MCAO.One week after operation,MCAO group was randomly divided into the stroke group and the stroke plus CUMS group.The MCAO group was randomly divided into the stroke group and the stroke + CUMS group.Stroke group and normal group were given cage processing,CUMS group and CUMS plus stroke group were given single cage feeding combined with CUMS.2.The degree of neurological deficit was assessed by Longa method.Depressive behaviors and cognitive deficits were measured by the change of body weight,SP index,OFT and Y maze.3.The relative expression levels of Sur1,Kir6.1,Kir6.2 and BDNF in the hippocampus was tested by reverse transcription-polymerase chain reaction(RT-PCR).4.The data were analyzed statistically by ANOVA of repeated measurement data.The multiple comparison was used by the LSD test.Inspection level p is 0.05.Results1.Behavior results: before stress process,there was no significant difference between each group(P>0.05).(1)The rate of weight change: compared with the control group and stroke group,the body weight measurement of PSD group increased slowly on day 21 of CUMS,the difference was statistically significant(P<0.05).(2)Sucrose preference index: at the 21 st day after stress onset,SP index of PSD group were lower than that of normal group and stroke group and depression group,the difference was statistically significant(P<0.05).(3)Open-field test: at the 21 st day of stress scores of open-field test in PSD group were significantly lower than that of normal group and stroke group(P<0.05).(4)Y maze: on day21 of stress,the percentage of the new arm stay and correct alternation in the PSD group was significantly lower than that of normal group?stroke group and depression group(P<0.05).2.RT-PCR results: expression levels of Sur1,Kir6.1,Kir6.2 and BDNF mRNA of rats hippocampus among control group,stroke group and PSD group had no significant difference(?>0.05).On the third week of CUMS,compared with control group,the expression level of Sur1 and BDNF mRNA in rat hippocampus in stroke group were significantly higher(?<0.05),the expression level of Sur1 and BDNF of PSD group was lower than that of control group and stroke group(?<0.05).Compared with control group,kir6.1 mRNA in PSD group was lower,the difference was significant statistically(?<0.05).Levels of Kir6.2 mRNA exited no change during the whole CUMS process(?>0.05).Conclusions1.Post stroke mild stress downregulates hippocampal Sur1,Kir6.1and BDNF mRNA expression of stroke rats.2.Post stroke mild stress aggravates depressive degree and cognitive impairment of stroke rats which is more serious than that of rats suffering CUMS process.Mild stress may suppress hippocampal Sur1,and Sur1/Kir6.1 channel may influence congnitive function via regulating the hippocampal expression of BDNF in rats.