Hypoxia preconditioning induced HIF-1α promotes glucose metabolism and protects mitochondria in liver I/R injury.

BACKGROUND: Ischemia and reperfusion (I/R) injury is one of the main lesions after liver transplantation. This study aims to detect hypoxia-induced HIF-1α protects transplanted liver against I/R injury by promoting glucose metabolism to decrease mitochondrial injury and apoptosis on rat model. METHODS: The rats were given a treatment of 90 min non-lethal hypoxic preconditioning to induce and increase the HIF-1α expression. The autologous orthotopic liver transplantation model was used to imitate liver I/R injury. RESULTS: Hypoxic-induced HIF-1α was detected to increase in liver tissue after 90-minute hypoxic environment (HP vs. Ctrl, *P<0.001). After operation, the expression of HIF-1α in liver tissue was also stayed at a high level. At 24h after operation, several genes were promoted, such as the levels of HK-2 (HP vs. AT, 24h, *P=0.004), Lactate dehydrogenase (LDHA) (HP vs. AT, 24h, *P=0.003), pyruvate dehydrogenase kinase (PDK-1) (HP vs. AT, 24h, *P=0.007), even the NF-κB and Erk pathways. From the TUNEL assay, the apoptosis in hypoxic preconditioning liver tissue was decreased compared with non-HP operative group at 12h after operation. The expressions of cleaved-caspase 3 (HP vs. AT, *P=0.0119) and PARP (HP vs. AT, *P=0.0134) in HP group were also significantly lower than AT group. CONCLUSION: The hypoxia-induced HIF-1α could promote glucose metabolism to protect hepatocellular mitochondria from damage. It could be a useful way to protect liver against I/R injuries and inflammatory injury, and particularly promote the recovery of graft function.

Significance of the change in mitochondrial aspartate aminotransferase after rat's liver transplantation / 国际外科学杂志

Objective To investigate the change of the mitochondrial aspartate aminotransferase (mAST), and the ratio of m-AST and aspartate aminotransferase (AST) in rat orthotopic liver transplantation.Methods We used the rat autologous orthotopic liver transplantation modelin which liver was infused by portal vein. Group A: Autologous orthotopic liver transplantation. Group B: Sham control group of normal rats. To measure the m-AST, AST and ALT in rat serum at each time, the ratio of m-AST/AST was calculated to observe the changes after surgery. Results The ALT of group A after 1 h was 1149.2 U/L, while the ALT of group B was 111.3 U/L; The AST of group A ofter 1 h was 819.5 U/L, while the AST of group B was 128.2 U/L; The m-AST of group After 1 h was 290.8 U/L, while the m-AST of group B was 40.5 U/L. The levels of m-AST, AST and ALT in group A were significantly higher than group B (P ＜ 0. 05).Group A significantly increased the degree of liver damage compared with group B. The ratio of m-AST/AST in group A changed with time obviously. Because the haff-life of m-AST in serum was shorter than that of AST, and AST in this study returned to normal slowly, the ratio of m- AST/AST in A group decreased after 6 h and the number is 0. 12. It indicating that the damage of mitochondria in rat liver cells has been restored after 6h. Conclusions It will be better to judge the prognosis of liver transplantation from the changes of serum m-AST in rats. And it seems earlier to reflect the injury or recovery of liver cell compared with AST.It also has the guiding values to diagnose and treat the damage of liver cells and mitochondrial in the rat liver transplantation.

Effects of hypoxia inducible factor-1α with high expression mediated by hypoxia precondition on the JNK signaling pathway in rats received orthotopic liver autotransplantation / 中华消化外科杂志

Objective To investigate the expression of hypoxia inducible factor-1α(HIF-1α)in the transplanted liver in rats and the role of HIF-1α in the JNK signaling pathway.Methods Ninety-six SD rats were randomly divided into normal control(NC)group,autotransplantation(AT)group,hypoxia preconditioning (HP)+ AT group according to simple random sampling method.No treatment was applied to the rats in the NC group except for blood vessel separation.Stable rat models of 70％ AT was established in the AT group.Rats in the HP + AT group were given 8％ oxygen mixed gas for 90 minutes before the operation.The levels of alanine aminotransferase(ALT)and aspartate aminotransferase(AST)were detected at 1,2,12,24 hours after operation,and the expression of HIF-1α in the hepatic tissue,mRNA expression of c-Jun,and protein expression of Cleaved Caspase-3 were detected by immunohistochemical staining,reverse transcription-polymerase chain reaction and Western blot,respectively.All data were analyzed using the analysis of variance or t test.Results The levels of ALT and AST in the HP + AT group were significantly lower than those in the AT group,while higher than those in the NC group at 1,2,12 and 24 hours after the operation(F=2631.371,1177.642,810.383,682.848;743.618,1095.522,375.995,580.613,P ＜0.05).The protein expression levels of HIF-1α in the AT group were significantly lower than those in the HP + AT group,but higher than those in the NC group at 1,2,12 and 24 hours after operation(F = 191.737,284.482,459.419,213.782,P ＜ 0.05).The mRNA expression levels of c-Jun in the HP + AT group were significantly lower than those in the AT group,while higher than those in the NC group at 1,2 and 12 hours after operation(F = 66.211,53.169,9.645,P ＜ 0.05).There was no significant difference in the mRNA expression of c-Jun among the 3 groups at 24 hours after operation(F = 1.100,P ＞ 0.05).The protein expressions of Cleaved Caspase-3 in the HP + AT group were significantly lower than those in the AT group,while higher than those in the NC group at 1,2,12 and 24 hours after the operation(F =23.133,31.158,14.347,29.043,P ＜ 0.05).Conclusion High expression of HIF-1α after HP inhibits apoptosis of hepatic cells and alleviates ischemia reperfusion injury of hepatic tissues by suppressing JNK activation,down-regulating protein expression of Cleaved Caspase-3 after orthotopic liver transplantation in rats.