Abstract: Objective To evaluate the effect of inhaled hydrogen gas on DNA methylation in hippocampal tissues of septic mice. Methods Fifty-four male C57BL/6 mice were divided into 3 groups using a random number table: sham operation group (group Sham), sepsis group (group Sepsis) and hydrogen gas group (group Sepsis+H2), 18 mice for each group. Sepsis model was produced by cecum ligation and puncture (CLP) in group Sepsis and group Sepsis+H2. Mice in group Sepsis+H2 inhaled 2% hydrogen gas mixed with air at 1 h and 6 h after surgery. Mice in group Sham were performed only laparotomy without CLP. At 1, 3 and 7 d after sham operation or CLP, hippocampal tissues were taken from the mice in the three groups, and the global DNA methylation was measured by colorimetry. Real-time PCR was used to detect the mRNA expression levels of DNA methyltransferase enzymes (DNMT1, DNMT3a, and DNMT3b). Western blot assay was used to detect the protein expression levels of DNMT1, DNMT3a and DNMT3b. Results Compared with group Sham, the global DNA methylation in hippocampal tissues was significantly decreased at 1, 3 and 7 d after operation in group Sepsis(P＜0.05), the mRNA and protein expression levels of DNMT1 and DNMT3a were significantly increased, while the level of DNMT3b was decreased in group Sepsis (P＜0.05). Compared with group Sepsis, the global DNA methylation was significantly increased in group Sepsis+H2 (P＜0.05), the mRNA and protein expression levels of DNMT1 and DNMT3a were significantly decreased, and the level of DNMT3b was significantly increased in group Sepsis+H2 (P＜0.05). Conclusion Inhaled hydrogen gas could corrected DNA methylation disorders in the hippocampus of septic mice. The correction of DNA methylation disorders is one of the mechanisms of hydrogen gas therapy for sepsis-associated encephalopathy.

Key words: hydrogen, sepsis, DNA methylation, hippocampus