Inhalation of high concentrations of hydrogen ameliorates liver ischemia/reperfusion injury through A2A receptor mediated PI3K-Akt pathway

Abstract Background and aims This study explored the hepatoprotection of high concentrations of hydrogen (HCH) inhalation in a mouse hepatic ischemia/reperfusion (I/R) injury model and the potential mechanism. Methods To explore the role of the PI3K-Akt pathway in the hepatoprotection of HCH, C57BL/6 mice were randomly divided into five groups: Sham, I/R, I/R + HCH, LY294002 (PI3K inhibitor) + I/R + HCH, and LY + I/R groups. Mice received inhalation of 66.7% hydrogen and 33.3% oxygen for 1 h immediately after surgery. LY294002 was intravenously injected at 10 mol/kg. To explore whether PI3K-Akt pathway activation was mediated by the A 2A receptor, additional four groups were included: ZM241385 (A 2A receptor antagonist) + I/R + HCH, ZM241385 + I/R, bpv(HOpic) (PTEN inhibitor) + I/R, and ZM241385 + bpv + I/R + HCH. Six hours after I/R, serum biochemistry, histological examination, Western blotting, and immunohistochemistry were performed to evaluate the hepatoprotection of HCH and the role of the PI3K-Akt pathway and A 2A receptor in this protection. Results Liver dysfunction, hepatic pathological injury, infiltration of inflammatory cytokines, and hepatocyte apoptosis were observed after hepatic I/R, accompanied by inhibition of the PI3K-Akt pathway. HCH significantly improved liver function, reduced serum inflammatory cytokines, and inhibited hepatocyte apoptosis, and also induced the PI3K-Akt pathway activation. In the presence of LY294002 or ZM241385, the protective effects of HCH were markedly attenuated, but the effects of ZM241385 were reversed by bpv(HOpic). Conclusion Our findings indicate that HCH may protect the liver against I/R injury through the A 2A dependent PI3K-Akt pathway.