Age-related changes in reactive oxygen species production in rat brain homogenates

The generation of reactive oxygen species (ROS) and resultant oxidative stress have been implicated in the mechanism of brain dys function due to age-related neurodegenerative diseases or exposure to environmental chemicals. We have investigated intrinsic age related differences in the ability of the various brain regions to generate ROS in the absence and presence of Fe2+. ROS production in crude brain homogenates from adult rats was linear with respect to time and tissue concentration, and was stimulated to a greater extent by Fe2+ than was TEARS production. ROS production was then determined in homogenates from cerebral cortex, striatum, hippocampus, and cerebellum of 7-day-old, 14-day-old, 21-day-old, adult (3-6-month old), and aged (24-month-old) rats using the fluorescent probe 2',7'-dichlorodihydrofluorescin (DCFH). Basal levels of ROS production were similar in 7-, 14-, and 21-day olds, increased in adults, and highest in aged rats, and did not differ between brain regions. ROS production was stimulated by Fe2+ (0.3-30 mu M) in a concentration-dependent manner in all brain regions. However, the stimulation of ROS production by Fe2+ varied with age. ROS production was greater in 14- and 21-day-old rats compared with adult and aged animals. ROS production in 7-day-old rats was decreased at low Fe2+ concentrations and increased at high Fe2+ concentrations compared to adult and aged rats. These data show that brain homogenates from neonatal rats respond differently to Fe2+, and suggest that developing animals may be more sensitive to oxidative stress in the brain after exposure to toxicants. Published by Elsevier Science Inc.