title: The effects of reactive oxygen species on amphibian aging.
abstract: To clarify the role of reactive oxygen species (ROS) in the aging process of amphibians, antioxidant enzyme activity and indexes of ROS damage were investigated biochemically using the livers of 3- and 10-year-old Rana nigromaculata frog males and females. Findings revealed no significant difference in survival rate between males and females. Antioxidant enzyme activity displayed an age-related decline. Superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPx) activity in 10-year-old liver decreased 40-80% from 3-year-old liver levels. In contrast, urate oxidase activity in the 10-year-old liver increased more than 200% from 3-year-old liver levels. At the same time levels of ROS damage, including the concentration of inorganic peroxide and thiobarbituric acid reactive substances (TBARS), greatly increased with age. Liver catalase from 10-year-old frogs proved to be more susceptible to aminotriazole and urea, losing approximately 80% of its original activity after 30 min of treatment. It seems likely that liver catalase in older frogs has diverged from liver catalase in younger frogs through oxidative modification. These findings suggest that a decrease in the activity of antioxidant enzymes over time results in increased levels of ROS damage in the livers of older frogs.
authors.affiliation: Institute for Amphibian Biology, Graduate School of Science, Hiroshima University, Higashihiroshima 739-8526, Japan. akashiwa@hiroshima-u.ac.jp
authors.forename: Keiko
authors.initials: K
authors.lastname: Kashiwagi
authors.forename: Tadashi
authors.initials: T
authors.lastname: Shinkai
authors.forename: Eiji
authors.initials: E
authors.lastname: Kajii
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kashiwagi
mesh_terms: D000375:Aging / Q000187:drug effects*; D000640:Amitrole / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D002374:Catalase / Q000037:antagonists & inhibitors / Q000378:metabolism; D005260:Female; D005979:Glutathione Peroxidase / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000201:enzymology; D008297:Male; D011898:Ranidae / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000494:pharmacology*; D013482:Superoxide Dismutase / Q000378:metabolism; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism; D014503:Urate Oxidase / Q000378:metabolism; D014508:Urea / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D017382:Reactive Oxygen Species; D017392:Thiobarbituric Acid Reactive Substances; D014508:Urea; D006861:Hydrogen Peroxide; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D014503:Urate Oxidase; D000640:Amitrole