Role of Nrf2/ARE pathway in hydrogen-rich saline-induced reduction of liver ischemia-reperfusion injury in rats undergoing liver autotransplantation

Objective To investigate the role of nuclear factor E2-related factor 2(Nrf2)/antioxidant response element(ARE)pathway in hydrogen-rich saline-induced reduction of liver ischemia-reperfusion(I/R)injury in rats undergoing liver autotransplantation. Methods Thirty-two SPF adult male Sprague-Dawley rats, aged 8–10 weeks, weighing 200–250 g, were randomly divided into 4 groups(n=8 each)using a random number table: sham operation group(group S); liver autotransplantation group(group T); hydrogen-rich saline group(group H); Nrf2 inhibitor all-trans retinoic acid + hydrogen-rich saline group(group A). In group A, all-trans retinoic acid 7 mg/kg was injected intraperitioneally once a day for 2 consecutive days, and the model of liver autotransplantation was established at 10 h after the last administration.In H and A groups, hydrogen-rich saline 6 ml/kg was injected through the infrahepatic inferior vena cava at 5 min before establishment of the model.At 6 h after the portal vein was unclamped(at 6 h after the end of operation in group S), blood samples were obtained for determination of serum alanine aminotransferase(ALT), aspartate aminotransferase(AST), tumor necrosis factor-alpha(TNF-α), and interleukin-10(IL-10)concentrations.The rats were then sacrificed, and livers were removed for microscopic examination of pathologic changes which were scored and for determination of malondialdehyde(MDA)content, superoxide dismutase(SOD)activity, and expression of Bcl-2, Bax, Nrf2 and heme oxygenase-1(HO-1)mRNA. Results Compared with group S, the serum ALT, AST and TNF-α concentrations, pathologic score, and MDA content were significantly increased, the SOD activity and serum IL-10 concentrations were decreased, the expression of Bax, Nrf2 and HO-1 mRNA was up-regulated, and the expression of Bcl-2 mRNA was down-regulated in group T(P<0.05). Compared with group T, the serum ALT, AST and TNF-α concentrations, pathologic score, and MDA content were significantly decreased, the SOD activity and serum IL-10 concentrations were increased, the expression of Bcl-2, Nrf2 and HO-1 mRNA was up-regulated, and the expression of Bax mRNA was down-regulated in group H(P<0.05). Compared with group H, the serum ALT, AST and TNF-α concentrations, pathologic score, and MDA content were significantly increased, the SOD activity and serum IL-10 concentrations were decreased, the expression of Bcl-2 and HO-1 mRNA was down-regulated, and the expression of Bax mRNA was up-regulated in group A(P<0.05). Conclusion The mechanism by which hydrogen-rich saline reduces liver I/R injury is associated with activated Nrf2/ARE pathway and up-regulated expression of HO-1 in rats undergoing liver autotransplantation. Key words: Hydrogen; Liver transplantation; Reperfusion injury; NF-E2-related factor 2; Response elements