Age-related changes in antioxidant enzyme activities and lipid peroxidation in lungs of control and sulfur dioxide exposed rats

Antioxidant defenses within the lung are pivotal in preventing damage from oxidative toxicants. There have also been several reports with conflicting results on the antioxidant system during aging. In this study, we attempted to investigate age-related alterations in both antioxidant enzyme activiti es and thiobarbituric acid-reactive substances (TBARS), a product of lipid peroxidation, in the whole lung of control and sulfur dioxide (SO2) exposed rats of different age groups (3-, 12-, and 24-months-old). Swiss-Albino Ma le rats were exposed to 10 ppm SO2 1 hr/day, 7 days/week for 6 weeks. The a ntioxidant enzymes examined include CuZn-superoxide dismutase (SOD), catala se (CAT), glutathione peroxidase (GSH-Px) and glutathione S-transferase (GS T). A mixed pattern of age-associated alterations in antioxidant activities was observed. SOD, GSH-Px and GST activities were increased with age, but CAT activity was decreased. Lung SOD, GSH-Px and GST activities were also i ncreased in response to SO2. The level of TBARS was increased with age. SO2 exposure stimulated lipid peroxide formation in the lung as indicated by a n increase in the level of TBARS. These findings suggest that both aging an d SO2 exposure may impose an oxidative stress to the body. We conclude that the increase in the activities of the antioxidant enzymes of the lung duri ng aging, could be interpreted as a positive feedback mechanism in response to rising lipid peroxidation.