SKELETAL MUSCLE ANTIOXIDANT DEFENSE AND OXIDATIVE STRESS IN EXERCISE-TRAINED AGING-DELAYED AMES DWARF MICE
M.A. Romanick, S.G. Rakoczy, H.M. Brown-Borg
University of North Dakota,
Dept. of Pharmacology, Physiology, and Therapeutics,
P.O. Box 9037,
Grand Forks, ND 58202-9037
A correlation exists between aging and the degree to which
oxidative stress is experienced. The Ames dwarf mouse with
a life span one and one-half times that of wild type mice
has demonstrated heightened defense to oxidative stress in
a variety of tissues, including skeletal muscle. A previous
study demonstrated differences in oxidative stress response
to an acute bout of exercise in 3-, 12-, and 18-month-old
dwarf and wild type mouse muscle. This experiment examined
antioxidant enzyme activity and antioxidant substrate levels
in young and old dwarf and normal skeletal muscle following
a 6-week training period of swimming to observe the impact
of increased physical activity on antioxidant effect in an
aging context. Spectrophotometric assays for levels of the
antioxidant glutathione in its reduced (GSH) and oxidized
(GSSG) states and for activity of antioxidant enzymes,
catalase (CAT) and glutathione peroxidase (GPX), were
performed on hindlimb skeletal muscle tissue from 3-month-
and 18-month-old mice which were swum daily for one hour in
a 32°C water bath over the course of 6 weeks. Older dwarf
mice demonstrated increased catalase (CAT) and glutathione
peroxidase (GPX) enzyme activity levels compared to younger
dwarfs. Younger dwarf mice presented lower GPX activity
levels than young wild type mice, while older dwarf mice
showed increased GPX activity compared to older wild type
mice. GSH to GSSG ratios, indicators of oxidative stress,
were lower in young wild type mice. These data indicate,
especially with respect to GPX activity, that dwarf mice
exhibit heightened antioxidant defense in muscle with age
when trained with exercise, a finding consistent with
previous studies of dwarf mice in both acute exercise and
nonexercise conditions.
Key words:
skeletal muscle, exercise, aging, antioxidants
Problems or questions regarding this site should be directed to
webmaster@americanaging.org