2009-10-02 06:37:35
by Jean-Louis Santini Jean-louis Santini Thu Oct 1, 11:10 pm ET
WASHINGTON (AFP) The fountain of youth may exist after all, as a study showed
that scientists have discovered means to extend the lifespan of mice and
primates.
The key to eternal -- or at least prolonged -- youth lies in genetic
manipulation that mimics the health benefits of reducing calorie intake,
suggesting that aging and age-related diseases can be treated.
Scientists from the Institute of Healthy Ageing at University College London
(UCL) extended the lifespan of mice by up to a fifth and reduced the number of
age-related diseases affecting the animals after they genetically manipulated
them to block production of the S6 Kinase 1 (S6K1) protein.
Scientists have shown since the 1930s that reducing the calorie intake by 30
percent for rats, mice and -- in a more recent finding -- primates can extend
their lifespan by 40 percent and have health benefits.
By blocking S6K1, which is involved in the body's response to changes in food
intake, similar benefits were obtained without reducing food intake, according
to the study published in the US journal Science.
The results corroborated those of other recent studies.
"Blocking the action of the S6K1 protein helps prevent a number of age-related
conditions in female mice," explained UCL professor Dominic Withers, the
study's lead author.
"The mice lived longer and were leaner, more active and generally healthier
than the control group. We added 'life to their years' as well as 'years to
their lives.'"
The genetically altered female mice lived 20 percent longer -- living a total
of 950 days -- or over 160 days more than their normal counterparts.
At age 600 days, the equivalent of middle age in humans, the altered female
mice were leaner, had stronger bones, were protected from type 2 diabetes,
performed better at motor tasks and demonstrated better senses and cognition,
according to the study.
Their T-cells, a key component of the immune system also seemed more
"youthful," the researchers said, which points to a slowing of the declining
immunity that usually accompanies aging.
Male mice showed little difference in lifespan although they also demonstrated
some of the health benefits, including less resistance to insulin and healthier
T-cells. Researchers said reasons for the differences between the two sexes
were unclear.
"We are suddenly much closer to treatments for aging than we thought," said
David Gems of UCL's Institute of Healthy Aging, one of the authors of the
study, which was primarily funded by the Wellcome Trust.
"We have moved from initial findings in worm models to having 'druggable'
targets in mice. The next logical step is to see if drugs like metformin can
slow the aging process in humans."
Other studies have also found that blocking S6K1 were channeled through
increased activity of a second molecule, AMPK, which regulates energy levels
within cells.
AMPK, also known as a master "fuel gauge," is activated when cellular energy
levels fall, as takes place when calorie intake is reduced.
Drugs, such as the widely-used metformin, that activate AMPK are already being
used in human patients to treat type 2 diabetes.
Recent studies by Russian scientists suggested that metformin can extend mice's
lifespan.
Another drug, rapamycin, was found to extend the lifespan of mice, according to
a study published in the British journal Nature.
As rapamycin is already used in humans as an immunosuppresant -- to prevent a
patient from rejecting an organ after transplant -- it could not be
administered as an anti-ageing drug in its current form.
But rapamycin blocks S6K1 activity and could thus extend lifespan through its
impact on S6K1.
Seizing on the potential, US firm Sirtris Pharmaceuticals uses resveratrol, a
powerful anti-oxidant found in red wine, as well as other fruits than raisin.
Sirtris scientists -- including co-founder David Sinclair, also a researcher at
Harvard Medical School -- have found that resveratrol activates the production
of sirtuin proteins, which also unleash the same physiological effects as
reducing calorie intake.
Sirtris has produced highly concentrated doses of resveratrol and is currently
leading clinical trials with diabetes patients and others suffering from liver
and colon cancer.