Age-related changes in apoptosis in rat hippocampus induced by oxidative stress

Also known as programmed cell death, apoptosis is a sequence of events that leads to elimination of cells without releasing harmful substances into the surrounding area. Apoptosis may be induced by intracellular or extracellular signals. Certain apoptotic signals activate mitochondrial pro-apoptotic events and increase reactive oxygen species (ROS). Increased ROS production may lead to oxidative stress. The goal of our study was to characterize age-related changes in apoptosis induced by oxidative stress in the hippocampus. Rats 2, 7, 21 and 38 days old, and adult rats were used for our study. Hippocampal CA1, CA2, CA3 and dentate gyrus apoptosis, and hippocampal superoxide dismutase (SOD), glutathione peroxidase (GPx) enzyme activities and thiobarbituric acid reactive substances (TBARS) levels were measured. We found that numbers of hippocampal neurons were low in rats 2, 7 and 21 days old (CA1, p < 0.001; CA3, p < 0.05; gyrus dentatus, p < 0.001). The terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) positive cell count was highest in the CA1 and dentate gyrus of 21-day-old rats. Among 21-day-old rats, the hippocampal TBARS levels and SOD enzyme activity were high, whereas GPx activity was low. These results demonstrate that the hippocampal CA1 and dentate gyrus of 21-day-old rats are more prone to damage by oxidative stress.