Loss Finding May One Day Save Physiques
ANTONIO (Feb. 12, 2010) Hey guys, remember the muscle shirts
we wore in our teens and 20s? After the age of 40 that meager part
of our wardrobes usually is obsolete. Yes, at the big 4-0 we begin
to lose muscle, and by age 80 up to a third of it may be gone. It's
an inevitable process of aging called sarcopenia.
does sarcopenia happen and can it be stopped? A study conducted
in mice with accelerated muscle loss at The University of Texas
Health Science Center at San Antonio provides this insight: Less
protection from antioxidants and more damage from oxidative stress
results in impairment to cells' energy centers, which slowly leads
to death of muscle cells.
directed by Holly Van Remmen, Ph.D., associate professor with the
university's Barshop Institute for Longevity and Aging Studies and
the Department of Cellular and Structural Biology, found that without
a certain antioxidant enzyme to balance the formation of harmful
reactive oxygen species (ROS), cellular energy centers called mitochondria
fail to work properly. The mitochondria even add to the spate of
ROS molecules and release factors leading to cell death.
impaired function of mitochondria also has a detrimental effect
on the way motor neurons 'talk' to the muscle to achieve muscle
contraction," Dr. Van Remmen said. "This interaction occurs
at a specialized synapse where the nerve and muscle come in close
contact." This key structure is called the neuromuscular junction,
and weaker muscles
C. Jang, Ph.D., a leading author in the study, investigated mice
that were genetically engineered to lack an antioxidant enzyme called
copper-zinc superoxide dismutase. He compared mitochondria from
these mice and normal mice and found reduced function of the energy
centers in the enzyme-deficient mice. This contributed to more cell
death and muscle atrophy in the rodents. "As a result, their
muscles were a lot smaller and weaker," Dr. Van Remmen said.
gleaned about muscle loss can help scientists better understand
other neuromuscular diseases such as amyotrophic lateral sclerosis
(Lou Gehrig's disease). "Age-related muscle atrophy is a complex
process and involves multiple systems," Dr. Van Remmen said.
"There are, however, common mechanisms occurring in sarcopenia
and other neuromuscular diseases. By understanding the mechanisms
underlying age-related muscle atrophy and alterations at the neuromuscular
junction, we should be able to gain insight that will help us to
discover new therapeutic interventions."
a muscle-preserving therapy is one day developed, future generations
of young men will be able to keep their muscle shirts a bit longer.
A grant from the National Institute on Aging supported this project,
along with a Julie Martin Mid-Career Award in Aging Research to
Dr. Van Remmen from the American Federation for Aging Research.
Co-authors from the UT Health Science Center are Youngmok Jang,
Ph.D.; Michael Lustgarten, Ph.D.; Yuhong Liu; Florian Muller, Ph.D.;
Arunabh Bhattacharya, Ph.D.; Hanyu Liang, Ph.D.; Adam Salmon, Ph.D.;
and Arlan Richardson, Ph.D. Other co-authors are Susan Brooks, Ph.D.,
and Lisa Larkin, Ph.D., of The University of Michigan and Christopher
Hayworth, Ph.D., of The University of Texas at Austin. Drs. Van
Remmen and Richardson have joint appointments with the South Texas
Veterans Health Care System. This paper was published online by
The FASEB Journal on Dec. 29, 2009.
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