-- Mary Elizabeth Dallas
THURSDAY, Aug. 29 (HealthDay News) -- By suppressing a gene
involved in metabolism and energy balance, researchers extended the
average lifespan of a group of mice by about 20 percent -- thought
to be one of the longest lifespan increases ever observed in
This is the equivalent of extending the average human lifespan
by 16 years, from 79 to 95 years old, the U.S. National Institutes
of Health researchers said.
Although the study also revealed that this gene, known as mTOR,
does not affect every tissue and organ the same way, the
researchers said their findings could help scientists develop new
therapies for aging-related diseases -- such as Alzheimer's -- that
target specific organs.
Scientists note, however, that research conducted in animals
often fails to provide similar results in humans.
"While the high extension in lifespan is noteworthy, this study reinforces an important facet of aging: It is not uniform," lead researcher Dr. Toren Finkel, of the NIH's National Heart, Lung, and Blood Institute, said in an institute news release. "Rather, similar to circadian rhythms, an animal might have several organ-specific aging clocks that generally work together to govern the aging of the whole organism."
In conducting the study, the researchers engineered mice that
produce only the minimum amount of mTOR needed for survival. With
about 25 percent of the normal amount of this protein, the
engineered mice were smaller than average but otherwise normal.
The study, published Aug. 29 in the journal
Cell Reports, found that the average lifespan was 28 months
for engineered male mice and 31.5 months for female mice. In
contrast, the normal male mice had an average lifespan of 22.9
months, and the normal female mice had an average lifespan of 26.5
Seven of the eight mice that lived the longest lives were
engineered mice, the researchers found. Although the engineered
mice aged better overall, the researchers pointed out that
improvement was seen only in specific organs.
For example, the engineered mice retained better memory and
coordination as they aged, but their bones deteriorated more
quickly than normal. In addition to more bone loss, the engineered
mice also were more vulnerable to infection. The researchers said
this could signal a compromised immune system.
They added that more research is needed to determine how aging
in different tissues is linked on the molecular level.
The U.S. National Institute on Aging has more about
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