Role of mitochondria in cell apoptosis during hepatic ischemia-reperfusion injury and protective effect of ischemic postconditioning

Abstract

Aim: To investigate the role of mitochondria in cell apoptosis during hepatic ischemia-reperfusion injury and protective effect of ischemic postconditioning (IPC).

Methods: A rat model of acute hepatic ischemia-reperfusion was established, 24 healthy male Wistar rats were randomly divided into sham-operated group, ischemia-reperfusion group (IR) and IPC group. IPC was achieved by several brief pre-reperfusions followed by a persistent reperfusion. Concentration of malondialdehyde (MDA) and activity of several antioxidant enzymes in hepatic tissue were measured respectively. Apoptotic cells were detected by TdT-mediated dUTP-biotin nick end labeling (TUNEL) and expression of Bcl-2 protein was measured by immunohistochemical techniques. Moreover, mitochondrial ultrastructure and parameters of morphology of the above groups were observed by electron microscope.

Results: Compared with IR group, the concentration of MDA and the hepatocellular apoptotic index in IPC group was significantly reduced (P<0.05), while the activity of antioxidant enzymes and OD value of Bcl-2 protein were markedly enhanced (P<0.05). Moreover, the injury of mitochondrial ultrastructure in IPC group was also obviously relieved.

Conclusion: IPC can depress the synthesis of oxygen free radicals to protect the mitochondrial ultrastructure and increase the expression of Bcl-2 protein that lies across the mitochondrial membrane. Consequently, IPC can reduce hepatocellular apoptosis after reperfusion and has a protective effect on hepatic ischemia-reperfusion injury.

Figure 1

Bcl-2 expression in sham, IR and IPC groups (× 200). A: Bcl-2 expression in sham group, B: Bcl-2 expression in IR group, C: Bcl-2 expression in IPC group.

Figure 2

TUNEL staining in sham, IR and IPC groups (× 200). A: TUNEL staining in sham group, B: TUNEL staining in IR group, C: TUNEL staining in IPC group.

Figure 3

Morphological change of hepatocellular apoptosis in IR group (TEM × 15000).

Figure 4

Mitochondrial ultrastructure in sham, IR and IPC groups (TEM × 15000). A: Mitochondrial ultrastructure in sham group, B: Mitochondrial ultrastructure in IR group, C: Mitochondrial ultrastructure in IPC group.