Pulmonary antioxidant defences and protein damage during the ageing process of both sexes.

The free radical theory holds that the senescence is caused by oxidative damage that results from an imbalance between reactive oxygen and nitrogen species (RONS) and antioxidant defences. Hence, it plays an important role in the field of gerontology. We evaluated, in male and female rats, the activities of the antioxidant enzymes catalase (CAT), glutathione peroxidase (GPx), and total superoxide dismutase (tSOD), as well as oxidative protein damage in pulmonary tissue at 3, 6, 12, and 20 months of age. The results show an increase in the activities of all antioxidant enzymes at 12 months of age in female rats, suggesting an association with the reproductive life cycle. Protein damage in female pulmonary tissues did not change significantly throughout the ageing process. In male rats, the activity of GPx in 20 months of age showed an inter-gender increase, while the tSOD and GPx showed higher activities in 20 months of age in the intra-gender analysis. The male lung showed higher protein damage at 6 months of age. These findings suggest that antioxidant enzymatic activity is connected to the reproductive life cycle.