Effects of aging or diet on oxidative modification and antioxidant enzymes

Aging is a risk factor for the development of many diseases. The mechanisms by which aging and age-related diseases progress are not entirely clear, however, evidence suggests that aberrant amounts of reactive oxygen species (ROS) play a role in both the aging process and the pathogenesis of age-related maladies. Oxidative stress and resulting oxidative modifications of lipids and proteins have been linked to cellular dysfunction and disease, and specifically implicated in the development of several age-related afflictions. A decline in cardiac and hepatic function is associated with aging, and previous studies report a relationship between oxidative stress and the occurrence of heart and liver disease. The objective of this study was to determine whether aging or dietary–induced oxidative stress caused deleterious oxidative modifications to the cellular content of the heart and liver, and if age or diet affect the expression of antioxidant enzymes. Fischer 344 male rats at 6, 12, and 18 months of age were exposed to oxidative stress-inducing diets (high fat or high homocysteine). Lipid peroxidation was determined as an indicator of oxidative modification. In addition, the expression levels of antioxidant enzymes, superoxide dismutase (MnSOD and ZnSOD), glutathione peroxidase 1 (GPX1), and catalase, were determined at the RNA and protein level by RT-PCR and western blot respectively. This study found that aging and diet are associated with increased oxidative modification, as well as with alterations to the expression of antioxidant enzymes.