Bcl-2 and Bax expression for hepatocellular apoptosis in a murine endotoxin shock model.

Background/aims: Endotoxin-induced liver failure is characterized by necrosis and apoptosis of hepatocytes. The aim of this study was to establish the relation of the time-course of hepatic parenchymal cell apoptosis and necrosis in a murine endotoxin shock model and to characterize the role of the gene products of Bcl-2 and Bax in endotoxin-mediated hepatocellular apoptosis.

Methodology: Male Wistar rats were treated with 5 mg/kg body weight endotoxin, and the necrosis and apoptosis of hepatocytes were assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining and enzyme-linked immunosorbent assay for DNA fragmentation. Furthermore, Bcl-2 and Bax were analyzed by Western blotting.

Results: Endotoxin treatment led to liver dysfunction, and increased hepatic parenchymal cell apoptosis. Necrotic changes in hepatic tissues were found after the appearance of apoptosis. The apoptotic index increased up to 12 hours after endotoxin treatment. Western blot analysis revealed that the apoptosis was accompanied by a decrease of Bcl-2 protein and a relative increase of Bax protein. The apoptotic index decreased at 24 hours after the treatment synchronously with an increase in the ratio of Bcl-2 and Bax.

Conclusions: These results demonstrate a significant role of hepatocellular apoptotic processes in the later development of necrosis in the liver. The kientics of this apoptosis are directly proportionate to the disturbed ratio of Bcl-2 and Bax.