Iron Overload Induced Apoptotic Cell Death in Isolated Rat Hepatocytes Mediated by Reactive Oxygen Species

Isolated rat hepatocytes in culture were incubated with different concentrations of iron-sorbitol (50, 100, 150, and 200 µM) to assess the changes in reactive oxygen species (ROS) and lipid peroxidation leading to apoptotic hepatocyte cell death. The viability of hepatocytes was declined depending on the iron concentration. One hour incubation of the cells with 100 µM iron resulted in decreased of the hepatocyte viability down to 50% (EC₅₀ µM). Cellular glutathione (GSH) was depleted depending on the concentration of iron added to the hepatocytes in culture. Decline in cellular GSH was associated with elevation in reactive oxygen species (ROS) generation and formation of thiobarbituric acid reactive substances (TBARS) as index of lipid peroxidation. TBARS concentration was elevated in hepatocytes exposed to >100 µM of iron for 40 min. A significant increase in ROS formation was also observed in cells incubated with 75 µM of iron for 60 and 120 min. The consequences of ROS-mediated damages to hepatocytes were observed by DNA fragmentation, nuclear staining by propidium iddide and finally with induction of apoptotic hepatocyte cell death. Terminal deoxynucleotie transferase-mediated dUTP nick end labeling i.e. TUNEL assay (In situ- cell death-detection kit) and nuclear staining were also used to confirm apoptosis. These data clearly show that iron overload can cause apoptotic cell death in isolated hepatocytes and generation of ROS precedes other changes related to oxidative stress.