Mechanism underlying hydrogen-induced improvement of intestinal barrier function in septic mice: RhoA-mDia1 signaling pathway / 中华麻醉学杂志

ABSTRACT

Objective To investigate the relationship between the mechanism underlying hydrogeninduced improvement of intestinal barrier function and RhoA-mDia1 signaling pathway in septic mice.Methods Sixty male C57BL/6 mice,weighing 20-25 g,aged 6-8 weeks,were divided into 3 groups (n =20 each) using a random number table method:control group (group C),sepsis group (group S),and sepsis plus H2 group (group SH).Sepsis was produced by cecal ligation and puncture (CLP) in mice anesthetized with chloral hydrate.Mice in group SH inhaled air containing 2％ hydrogen for 1 h starting from 1 and 6 h after CLP.At 24 h after CLP,blood samples were obtained by cardiac puncture to measure the activity of serum diamine oxidase (DAO) and to count colony-forming unit (CFU) after bacterial culture,the small intestinal samples were obtained for microscopic examination of the ultrastructure of intestinal epithelial cells (with a transmission electron mnicroscope) and for measurement of the expression and distribution of tight junction protein ZO-1 in intestinal epithelial cells (by immunofluorescence) and expression of RhoA,expression and phosphorylation of myosin phosphatase target subunit 1 (MYPT1) and expression of mDia1 (by Western blot).The p-MYPT1/MYPT1 ratio was calculated.Results Compared with group C,the serum DAO activity and whole blood CFU counts were significantly increased,the expression of RhoA was up-regulated,and the expression of ZO-1 was down-regulated in S and SH groups,the p-MYPT1/MYPT1 ratio was significantly increased,and the expression of mDia1 was down-regulated in group S,and the p-MYPT1/MYPT1 ratio was significantly decreased,and the expression of mDia1 was up-regulated in group SH (P＜0.05).Compared with group S,the serum DAO activity,whole blood CFU counts and p-MYPT1/MYPT1 ratio were significantly decreased,the expression of RhoA was down-regulated,the expression of ZO-1 and mDia1 was up-regulated (P＜0.05),and the ultrastructure changes of intestinal tissues were significantly improved in group SH.Conclusion The mechanism by which hydrogen improves intestinal barrier function is related to inhibiting RhoA activity and increasing mDia1 activity in intestinal epithelial cells of septic mice.