Effect of metformin on hepatic ischemia-reperfusion injury and mechanism
Objective To investigate the effects of metformin on hepatic ischemia-reperfusion injury(IRI)and its molecular mechanism.Methods Totally,30 C57BL/6 mice were randomly divided into Sham group,ischemia reperfusion group(I/R group),ischemia reperfusion group+metformin group(I/R+MET group).Liver IRI model was established in I/R group and I/R+MET group,but not in Sham group.Mice in I/R+MET group were intraperitoneally injected with 200 mg/kg metformin daily before surgery,and the administration was stopped 24 h before surgery.Rats in Sham group and I/R group were intraperitoneally injected with equal volume of normal saline daily before surgery.The serum glutamic pyru-vic transaminase(ALT)and glutamic oxaloacetic transaminase(AST)concentrations in the three groups were determined by venous blood samples 6 h after operation.The apoptosis of liver cells in the three groups was analyzed by terminal-deoxynucleotidyl transferase mediated nick end labeling(TUNEL)staining kit.The oxidative stress reaction of the three groups of rats was detected by radioimmunoassay.The chan-ges of liver inflammatory factors in three groups of mice were analyzed by enzyme linked immunosorbent as-say(ELISA).AMP-activated protein kinase(AMPK)and UNC-51 like kinase 1(ULK1)and autophagy substrate p62 protein expression levels in the liver tissues of the three groups of mice were analyzed by Western blotting.One-way analysis of variance was used to compare the measurement data between groups.Results The levels of serum ALT and AST in I/R+MET group[(62.37±8.07),(121.51±20.45)U/L]were significantly lower than those in I/R group[(140.53±13.07),(187.19±18.73)U/L,t=18.150,7.489,P＜0.05].Inflammatory factors of mice liver tissue in the I/R+MET group[(55.70±6.36),(39.62±6.66),(64.12±5.33)pg/g]were lower than in the I/R group[(99.15±7.45),(82.73±8.90),(102.40±13.17)pg/g,t=18.580,14.030,9.630,P＜0.05].The serum MDA level in the I/R+MET group[(1.03±0.05)μmol/ml]was significantly lower than that in the I/R group[(1.73±0.14)μmol/ml,t=14.970,P＜0.05].The serum SOD level of mice in the I/R+MET group[(129.70±7.12)U/ml]was significantly higher than that in the I/R group[(99.50±10.66)U/ml,t=14.970,P＜0.05].The positive rate of TUNEL staining in liver tissue of mice in the I/R+MET group[(13.57±2.01)％]was significantly lower than that in the I/R group[(26.40±4.05)％,t=8.967,P＜0.05].The phosphorylation levels of AMPK and ULK1 in liver tissue of mice in the I/R+MET group(1.25±0.06,1.37±0.09)were significantly higher than those in the I/R group(0.65±0.07,0.96±0.06,t=19.480,11.670,P＜0.05).The level of autophagy substrate protein p62 in liver tissue of mice in the I/R+MET group(0.67±0.08)was significantly lower than that of mice in the I/R group(0.98±0.05,t=10.050,P＜0.05).Conclusion Metformin can promote autophagy by activating AMPK.It can relieve oxidative stress and inflammation caused by liver hypoxia and ischemia,and protect liver from IRI.
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