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Aging News & Information
Naked Mole-Rat in News Again as Scientists find
Longevity Champs have Slower Metabolism
 These old rats studied for years still not
giving up secret of long life
October 10, 2006 - The world’s longest living rodent – the naked
mole-rat – is in the research news again today as scientists continue to
probe for the secret to its longevity. The latest study of the hairless
tunnel-dweller suggests that the thyroid may hold the answer to why they
live 10 times longer than most regular mice. They found that the naked
mole-rat has significantly lower levels of thyroid hormone, which speeds
metabolism, and hope this leads to the secret of aging.
The study further strengthens the theory that the
faster an animal’s metabolism, the shorter its life, and vice versa,
said Mario Pinto, the study’s lead author. The thyroid releases hormones
that regulate metabolic rate, which is the rate your body uses up
energy.
“Thyroid hormones are key regulators of metabolism
and have been widely implicated to influence longevity,” the authors
wrote.
Pinto presented the study “Differential thyroid
hormone activity in rodents with different life spans” at a poster
session yesterday at Comparative Physiology 2006: Integrating Diversity.
The study was carried out by Pinto and Rochelle Buffenstein, City
College of New York.
Thyroid key to metabolic rate
The thyroid gland produces thyroxine (T4) which
converts to triiodothyronine (T3) in the presence of iodine. T3 is the
active component of T4 and is the key hormone in regulating metabolism,
Pinto said.
When an animal becomes cold, for example, its body
converts T4 to T3 to speed metabolism and warm the body, he explained.
“Mice strains that exhibit extended longevity tend
to have lower thyroid hormone concentrations than shorter living
strains,” the authors wrote. “Significant declines in thyroid hormone
correlate well with enhanced maximum lifespan.”
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Naked Mole-Rat May Hold Answer to Longer Life but
Not Giving It Up, Yet
Researchers say they may change oxidative stress
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This 2002 photo by Cornell
University shows 22-year-old
Dara Neuman,
senior biology major, looking at a naked mole-rat older than she
was at the time. See more below main story. |
|
October 9, 2006 - Those of us most like the naked mole-rat may
outlive our contemporaries as does this friendly furless guy that lives
in the total darkness of underground burrows, yet holds the world
longevity record in the rodent kingdom. Why do they live so long?
Scientist have long studied that question without success, but a new
study says they show much higher levels of oxidative stress and damage
and less robust repair mechanisms than the short-lived mouse, findings
that could change the oxidative stress theory of aging, say the
scientists. Read more...
Read more
Aging News & Information |
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The study compared the levels of these thyroid
hormones among four groups of rodents with different life spans: mice,
guinea pigs, Damara mole-rats and naked mole-rats.
Mice live to about three and a half years; guinea
pigs live to six years; Damara mole-rats to 15 years; and naked
mole-rats to 28 years.
The animals were of different ages, but at
comparable points in their life spans. For example, the mole-rats, which
live 28 years, were two years old. The mice, which live about 3.5 years,
were six months old. The study determined the levels of T3 and T4 for
each animal.
T4 levels vary the most
T4 levels varied significantly between all of the
groups, with the shorter-lived groups having higher levels of T4 than
longer-lived groups. The mice, for example, had twice as much T4 as the
Damara mole-rats and had and three times more than that of the naked
mole-rats, Pinto reported. There was also a significant difference in T3
levels between the naked mole-rats and the guinea pigs, but not between
any of the other groups.
“These hormone concentration differences correlate
with maximum species lifespan and suggest an important regulatory role
of thyroid hormone in longevity,” the researchers concluded. However,
because T3 levels did not differ significantly among all the groups,
further research in this area using larger sample sizes (numbers of
rodents in each group) is needed, Pinto said.
Editor's Notes:
The American Physiological Society was founded in
1887 to foster basic and applied bioscience. The Bethesda,
Maryland-based society has 10,500 members and publishes 14 peer-reviewed
journals containing almost 4,000 articles annually.
APS provides a wide range of research,
educational and career support and programming to further the
contributions of physiology to understanding the mechanisms of diseased
and healthy states. In 2004, APS received the Presidential Award for
Excellence in Science, Mathematics and Engineering Mentoring.
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