Abstract: Objective To investigate the expression of multifunctional protein apurinic/ apyrimidinic endonuclease 1（APE1/Ref1） in different parts of liver cells in rats with acute-on-chronic liver failure （ACLF）. Methods 30 SD rats were random1y divided into normal control （n=15）,and ACLF model group （n=15）. ACLF models were established by intraperitoneal injections of CCL₄ combined with D-GalN and LPS and the establishment of liver failure model was confirmed by ultrasonography. Serum ALT,AST,and TBIL were detected by automatic biochemistry analyzer,pathologic changes in liver were revealed by HE staining,and APE1/Ref1 expression in cytoplasmprotein,nucleoprotein and total protein were detected by immunohistochemistry(IHC） and western blot. Results Success rate of model establishment screened by B ultrasound in this series was as high as 80%;serum ALT, AST and TBIL in control group were significantly lower than those in the model group [（56.5±16.0） U/L vs. （620.4±347.5） U/L,（178.7±36.5） vs. （1077.7±666.1） U/L,（3.2±0.6） μmol/L vs. （21.2±16.9） μmol /L,respectively,P<0.05 for all];the expression of APE1/Ref1 in model group was significantly lower than in the control[（6.8±1.3） IOD vs. （8.1±1.2） IOD,P<0.05];APE1/Ref1 in cytoplasmprotein in model group was significantly higher than that in control group[（0.91±0.08） IOD vs.（0.18±0.01） IOD,P<0.01],while APE1/Ref1 in nucleoprotein and total protein in model group were lower than those in control group[（0.71±0.01） IOD vs. （1.41±0.04） IOD,and （0.92±0.03） vs. （1.15±0.01） IOD,respectively,P<0.05 for both]. Conclusion APE1/Ref1 are co-expressed in hepatocellular cytoplasm and nucleus,presenting transferred expression from intranucleus to intracytoplasm with a declined expression manner.

Key words: Liver failure, Apurinic/apyrimidinic endonuclease 1, DNA damage, Oxidative stress, Rats