Expression Changes Of DNMT1 And Serum Levels Of Hcy And FA In Rat Models With Post-stroke Depression

Objective:To establish post-stroke depression(PSD)rat models and investigate the relationship between expression of DNA methyltransferase 1(DNMT1)protein,DNMT1 mRN A and serum levels of Homocysteine(Hcy)and Folic acid(FA)in PSD rat models and its role in pathogenesis of PSD.Methods:1.48 adult male Sprague-Dawley(SD)rats were randomly divided into normal group,depression group,stroke group and PSD group.Middle cerebral artery occlusion(MCAO)models established by intraluminal suture method in the stroke group.The depression rats models were made by chronic unpredictable medium stress(CUMS)combined with separately breeding.Focal cerebral ischemia models established by intraluminal suture method were used at first,and then PSD rat models established by chronic unpredictable mild stimulation with separately breeding were applied.2.Sucrose preference test(SPT),open field test(OFT)and weight of rats were used to evaluate the establishment of model rats is successful or not.3.Western blot(WB)and quantitative real-time PCR(qPCR)were used to detect the expression of DNMT1 protein and DNMT1 mRNA in the hippocampus of model rats,respectly.Enzyme-linked immunosorbent assay(ELISA)was used to detect the level of Hcy and FA in serum.Results:1.Test of behavior and weight of rats(1)SPT: Compared with the other 3 groups,sucrose water consumption of the PSD group was significantly lower(P<0.01).Compared with the normal group,sucrose water consumption of the stroke group and the depression group was significantly lower(P<0.01).Sucrose water consumption of the stroke group was significant lower than that of the depression group,difference was statistically significant(P<0.01).(2)OFT:1)Horizontal activity and vertical activity scores: Compared with the other 3 group s,activity scores of the PSD group was significantly lower(P<0.01).Compared with the normal group,activity scores of the stroke group and the depression group was significantly lower(P<0.01).Activity scores of the stroke group was significant lower than that of the depression group,difference was statistically significant(P<0.01).2)Time of Staying in the central grid: Compared with the other 3 group s,central grid staying time of the PSD group was significantly higher(P<0.01).Compared with the normal group,central grid staying time of the stroke group and the depression group was significantly higher(P<0.01).Central grid staying time of the stroke group was significant lower than that of the depression group,difference was statistically significant(P<0.01).3)Weight of rats: Compared with the other 3 groups,weight of the PSD group was significantly lower(P<0.01).Compared with the normal group,weight of the stroke group and the depression group was significantly lower(P<0.01).Weight of the stroke group was significant lower than that of the depression group,difference was statistically significant(P<0.01).2.Test of biochemistry and molecular biology(1)Western blot: Compared with the other 3 groups,relative DNMT1 protein expression in hippocampus of the PSD group was significantly lower(P<0.01).Compared with the normal group,relative DNMT1 protein expression of the stroke group and the depression group was significantly lower(P<0.01).There was no statistically difference between relative DNMT1 protein expression of the stroke group and the depression group(P>0.05).(2)qPCR: Compared with the other 3 groups,relative DNMT1 mRNA expression in hippocampus of the PSD group was significantly lower(P<0.01).Compared with the normal group,relative DNMT1 mRN A expression of the stroke group and the depression group was significantly lower(P<0.01).Relative DNMT1 mRNA expression of the stroke group was significant lower than that of the depression group,difference was statistically significant(P<0.01).(3)ELISA: Compared with the the other 3 groups,serum Hcy levels in the PSD group were significantly higher,but FA levels of PSD group were significantly lower,difference was statistically significant(P<0.01).Compared with the normal group,serum Hcy levels in the depression group and stroke group were significantly higher,but FA levels of both groups were significantly lower,difference was statistically significant(P<0.01).The serum FA levels of the stroke group was significant lower than that of the depression group,difference was statistically significant(P<0.01).Whereas there was no statistically difference between serum Hcy levels of the depression group and the stroke group(P>0.05).3.Correlation analysis:(1)There was a significantly negative correlation between relative expression of DNMT1 protein and DNMT1 mRNA in hippocampus and serum Hcy levels in all of group(P<0.01).(2)There was a significantly postive correlation between relative expression of DNMT1 protein and DNMT1 mRNA in hippocampus and serum FA levels in all of group(P<0.01).Conclusion:1.The combination of method of MCAO,CUMS and separately breeding can be successfully using to estabilish the PSD rat model.2.The low expression of DNMT1 protein and DNMT1 mRNA in hippocampus of PSD rat models were correlated with the increase of serum Hcy levels and the decrease of serum FA levels,these expression changes may be involved in the pathogenesis of post stroke depression.