Printen
Lage insuline waarden de sleutel tot langer leven*
Weer een onderzoek dat bevestigt dat voeding, zoals minder
vette voeding, die lagere insuline waarden veroorzaakt de lengte van leven
verlengd.
Insulin plays central role in
aging, Brown scientists discover
The life expectancy of fruit
flies increases an average of 50 percent when signals within cells of fat
tissue are blocked or altered, new Brown University research shows. Published
in the current issue of Nature, results of the study suggest that
reduced levels of insulin in one tissue regulates insulin throughout the body
to slow aging – a finding that brings science one step closer to cracking
the longevity code.
PROVIDENCE, R.I. — When the
chemical messages sent by an insulin-like hormone are reduced inside the fat
cells of fruit fly, the fly’s lifespan increases significantly, according to
new research conducted at Brown University.
A similar phenomenon has
already been observed in worms, according to Brown biology professor Marc
Tatar. But never before, Tatar says, has it been seen in fruit flies – whose
13,601 genes are shared in many ways by humans.
The experiment, detailed in
the current issue of Nature, also sheds important light on the role
insulin plays in the regulation of its own synthesis.
Block the hormone’s action
inside a few specific cells, the study shows, and the entire body stays
healthier longer. Scientists previously thought insulin triggered other
hormones to achieve this effect, but Tatar and his team found that insulin
regulates its own production and that it directly regulates tissue aging. The
principle: Keep insulin levels low and cells are stronger, staving off
infection and age-related diseases such as cancer, dementia and stroke.
“Think of the body like a
car,” Tatar says. “We knew insulin controlled the car’s speed by
regulating things like the gas pedal and the fuel injectors. Now we know that
insulin is also the fuel that makes the engine go.”
To conduct the experiment,
Tatar and four other Brown researchers created a line of genetically altered
flies which had dFOXO – a protein controlled by the fly equivalent of
insulin – inserted into the genetic material of fat cells near their brains.
Some flies were fed
mifepristone, a chemical copy of progesterone. This hormone activated a switch
attached to dFOXO, which in turn repressed the normal insulin signals inside
the cells. As a surprising result, insulin production was lowered throughout
the body. These flies lived an average of 50 days – 18 days longer than
flies whose insulin signals went unchecked.
“We now know that insulin is
a direct player in the aging process,” Tatar says. “So the research fits
some key puzzle pieces together. And it should change the way we think about
aging.”
Tatar’s research is part of
a growing body of evidence linking low insulin levels to increased longevity.
In recent years, scientists have found that mice and other animals live longer
when they eat a low-calorie diet, which reduces insulin production.
“Aging regulation is a
complex physiological process of nutritional inputs, metabolic regulation and
hormone secretion,” Tatar says. “But we still have so many unanswered
questions.”
Tatar and his team conducted their research over an 18-month period. The work was funded by the National Institutes of Health, the American Federation of Aging Research, the Ellison Medical Foundation and Pfizer Inc. (juli 2004)