Oxidative stress and extracellular matrices after hepatectomy and liver transplantation in rats

AIM:To investigate oxidative stress(OS)-mediated damage and the behavior of extracellular matrices in various rat models because shear stress with portal hypertension and cold ischemia/warm reperfusion injury trigger the liver regeneration cascade after surgery. These injuries also cause fatal liver damage.METHODS: Rats were divided into four groups according to the surgery performed: control; hepatectomy with 40% liver remnant(60% hepatectomy); orthotopic liver transplantation(OLT) with whole liver graft(100% OLT); and split OLT(SOLT) with 40% graft(40% SOLT). Survival was evaluated. Blood and liver samples were collected at 6 h after surgery. Biochemical and histopathological examinations were performed. OSinduced damage, 4-hydroxynonenal, ataxia-telangiectasia mutated kinase, histone H2AX, phosphatidylinositol 3-kinase(PI3K) and Akt were evaluated by western blotting. Behavior of extracellular matrices, matrix metalloproteinase(MMP)-9, MMP-2, tissue inhibitor of metalloproteinase(TIMP)-1 and TIMP-2 were also evaluated by western blotting and zymography. RESULTS: Although 100% OLT survived, 60% hepatectomy and 40% SOLT showed poor survival. Histopathological, immunohistological, biochemical and protein assays revealed that 60% hepatectomy, 100% OLT and 40% SOLT showed liver damage. PI3K and Akt were decreased in 60% hepatectomy and 40% SOLT. For protein expression, 40% SOLT showed differences in MMP-9, MMP-2 and TIMP-2. TIMP-1 showed differences in 60% hepatectomy and 40% SOLT. For protein activity, MMP-9 demonstrated significant differences in 60% hepatectomy, 100% OLT and 40% SOLT. CONCLUSION: Under conditions with an insufficient liver remnant, prevention of OS-induced damage via the Akt/PI3K pathway may be key to improve the postoperative course. MMP-9 may be also a therapeutic target after surgery.