摘要:
Oxidative stress is regarded as a main causal factor for natural
aging. This study tested the hypothesis that healthy elderly people
show higher oxidative DNA damage levels and lower antioxidative
enzymatic defense capacities than younger ones. In a cross-sectional
study, blood samples of 20 older (62-79 years) and 20 younger adults
(24-28 years) were compared with respect to oxidative DNA damage
in lymphocytes (alkaline elution), oxidative status (serum peroxides),
activities of superoxide dismutase (SOD) and glutathione peroxidase
(GPx) and concentrations of total glutathione. In accordance with
our hypothesis, elderly males showed a tendency towards higher levels
of oxidative DNA damage (single strand breaks). SOD activity inversely
correlated with the amount of DNA damage (single-strand breaks and
Fpg-sensitive modifications). Oxidative status was increased in
older men and negatively correlated with glutathione concentrations.
GPx activity was elevated and the SOD/GPx ratio lowered in older
males. Subjects with lowered SOD/GPx ratio showed increased oxidative
DNA damage. The results indicate age-related changes in the balance
between first step (SOD) and second step (GPx) of the enzymatic
antioxidant defense system. They support the assumption that a biological
optimum between antioxidative enzymes might be more important than
their absolute activities.