January 05, 2010
Superoxide Causes Muscle Atrophy With Age?

Blame shriveled muscles on free radicals.

If you're an aging baby boomer hoping for a buffer physique, there's hope. A team of American scientists from Texas and Michigan have made a significant discovery about the cause of age-related muscle atrophy that could lead to new drugs to halt this natural process. This research, available online the FASEB Journal (http://www.fasebj.org), shows that free radicals, such as reactive oxygen species, damage mitochondria in muscle cells, leading to cell death and muscle atrophy. Now that scientists understand the cause of age-related muscle loss, they can begin to develop new drugs to halt the process.

Just because free radical damage to mitochondria accelerate age-related muscle loss that does not prove that accumulated damage to mitochondria is the major reason for muscle loss as we age. It might be the major cause. But this study does not prove it.

Regardless of what causes muscle atrophy there's a decent chance stem cell therapies that generate new muscle cells could reverse it. Though it is possible that existing damaged mitochondria spew out toxic compounds that would mess up new cells created from stem cells.

Mice lacking an enzyme that breaks down superoxide suffered faster muscle loss.

"Age-related muscle atrophy in skeletal muscle is inevitable. However, we know it can be slowed down or delayed," said Holly Van Remmen, Ph.D., co-author of the study, from the Sam and Ann Barshop Institute for Longevity and Aging Studies at the University of Texas Health Science Center at San Antonio. "Our goal is to increase our understanding of the basic mechanisms underlying sarcopenia to gain insight that will help us to discover therapeutic interventions to slow or limit this process."

To make this discovery, Van Remmen and colleagues used mice that were genetically manipulated to prevent them from having a protective antioxidant (CuZnSOD). As a result of not being able to produce this antioxidant, the mice had very high levels of free radicals (reactive oxygen species) and lost muscle mass and function at a much faster rate than normal mice. Additionally, the muscles of the genetically modified mice were much smaller and weaker than those of normal mice. Scientists believe that these findings mimic effects of the normal aging process in humans, but at an accelerated rate.

Share |      Randall Parker, 2010 January 05 12:15 AM  Aging Mechanisms

dk said at January 5, 2010 2:31 AM:

i worked in eldercare....the argument agaisnt it being accumulated damage. Is that it usually happens very fast like over 6 months to a year. At least in males (where it is most noticable).

Lou Pagnucco said at January 5, 2010 9:11 AM:

Since free radicals participate in many very complex feedback loops that regulate the innate immune system and inflammatory response, maybe this is an instance where "inflammaging" - i.e. the immune response and systemic inflammation become dysregulated.

Hopefully, there are several links in these feedback loops that can be blocked.

Brian said at January 5, 2010 6:33 PM:

this may be good news from a political perspective. It connects one potential root cause of aging to a recognized disease. that means there's a profit to be made from pharmaceuticals that address the challenge.

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