Ozone-induced changes in oxidative stress parameters in brain regions of adult, middle-age, and senescent Brown Norway rats

A critical part of community based human health risk assessment following chemical exposure is identifying sources of susceptibility. Life stage is one such susceptibility. A prototypic air pollutant, ozone (O-3) induces dysfunction of the pulmonary, cardiac, and nervous systems. Long-term exposure may cause oxidative stress (OS). The current study explored age-related and subchronic O-3-induced changes in OS in brain regions of rats. To build a comprehensive assessment of OS-related effects of O-3, a tripartite approach was implemented focusing on 1) the production of reactive oxygen species (ROS) [NADPH Quinone oxidoreductase 1, NADH Ubiquinone reductase] 2) antioxidant homeostasis [total antioxidant substances, superoxide dismutase, gamma-glutamylcysteine synthetase] and 3) an assessment of oxidative damage [total aconitase and protein carbonyls]. Additionally, a neurobehavioral evaluation of motor activity was compared to these OS measures. Male Brown Norway rats (4, 12, and 24 months of age) were exposed to air or O-3 (0.25 or 1 ppm) via inhalation for 6 h/day, 2 days per week for 13 weeks. A significant decrease in horizontal motor activity was noted only in 4-month old rats. Results on OS measures in frontal cortex (FC), cerebellum (CB), striatum (STR), and hippocampus (HIP) indicated life stage related increases in ROS production, small decreases in antioxidant homeostatic mechanisms, a decrease in aconitase activity, and an increase in protein carbonyls. The effects of O-3 exposure were brain area-specific, with the STR being more sensitive. Regarding life stage, the effects of O-3 were greater in 4-month-old rats, which correlated with horizontal motor activity. These results indicate that OS may be increased in specific brain regions after subchronic O-3 exposure, but the interactions between age and exposure along with their consequences on the brain require further investigation.

Automated summary

The study found that exposure to ozone in elderly rats leads to an increase in oxidative stress in certain brain regions and has a negative impact on horizontal motor activity. Rats of different age groups respond differently to ozone, with younger rats showing more pronounced effects, especially in terms of horizontal motor activity.