Role of DNA methylation in sepsis-associated encephalopathy in mice / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the role of DNA methylation in sepsis-associated encephalopathy in mice.Methods A total of 144 clean-grade healthy male C57BL/6 mice,aged 6-8 weeks,weighing 20 -25 g,were divided into 4 groups (n=36 each) using a random number table method:sham operation group (group Sham),sepsis group (group Sepsis),sham operation plus S-adenosyl methionine (SAM) group (group Sham+SAM) and sepsis plus SAM group (group Sepsis+SAM).Sepsis was produced by cecum ligation and puncture (CLP).In Sham+SAM and Sepsis+SAM groups,DNA methylated methyl donor SAM 100 mg/kg was intraperitoneally injected at 1 h before operation and 12 h after operation,while the equal volume of normal saline was given instead in Sham and Sepsis groups.The cognitive function was assessed using Y-maze and contextual fear conditioning test at 1,3 and 7 days after CLP.Mice were sacrificed at 1,3 and 7 days after CLP,and the hippocampal tissues were taken for determination of genomewide DNA methylation (by colorimetric assay) and expression of DNA methyltransferase enzymes (DNMT1,DNMT3a,and DNMT3b),ten-eleven translocation (TET) enzymes (TET1,TET2 and TET3) and thymine-DNA glycosylase (TDG) mRNA (by fluorescent quantitative real-time).Results Compared with group Sham,the time of staying at the novel arm was significantly shortened,the percentage of time spent freezing and the total number of entries into each arm were reduced,genome-wide DNA methylation in hippocampal tissues was decreased at 1,3 and 7 days after CLP,the expression of DNMT1,DNMT3a,TET1,TET2,TET3 and TDG was up-regulated,and the expression of DNMT3b was down-regulated in group Sepsis (P＜0.05).Compared with group Sepsis,the time of staying at the novel arm was significantly prolonged,the percentage of time spent freezing and the total number of entries into each arm were increased,the expression of DNMT1,DNMT3a,TET1,TET2,TET3 and TDG mRNA was down-regulated,and the expression of DNMT3b was up-regulated in group Sepsis+SAM (P＜0.05).Conclusion DNA methylation is involved in the development of sepsis-associated encephalopathy in mice.