Small Calorie Reduction in Rats Slows Aging

[Guest guest]

http://tinyurl.com/np7ng

Scientists from the University of Florida's Institute on Aging have

found that eating a little less food and exercising a little more over

a lifespan can reduce or even reverse aging-related cell and organ

damage in rats.

The discovery, described this month in the journal Antioxidants and

Redox Signaling, builds on recent research in animals and humans that

has shown a more drastic 20 percent to 40 percent cut in calories

slows aging damage. The UF findings indicate even small reductions in

calories could have big effects on health and shed light on the

molecular process responsible for the phenomenon, which until now has

been poorly understood.

" This finding suggests that even slight moderation in intake of

calories and a moderate exercise program is beneficial to a key organ

such as the liver, which shows significant signs of dysfunction in the

aging process, " said Christiaan Leeuwenburgh, Ph.D., an associate

professor of aging and geriatric research at the UF College of

Medicine and the paper's senior author.

UF scientists found that feeding rats just 8 percent fewer calories a

day and moderately increasing the animals' activity extended their

average lifespan and significantly overturned the negative effects of

cellular aging on liver function and overall health.

An 8 percent reduction is the equivalent of a few hundred calories in

an average human diet and moderate exercise is equivalent to taking a

short walk.

To reveal the workings of the body's chemical climate when

aging-related damage happens, UF researchers tracked levels of

biomarkers - chemicals and molecules present in the liver - in groups

of rats. The liver, a crucial organ for maintaining good health during

aging, cleans the blood and helps regulate the body's immune system.

The researchers also plan to assess the same biomarkers in a study of

rats' hearts, muscle and brains.

The research team was surprised to find one of the biomarkers, RNA,

which is important for coding DNA and for protein synthesis, is more

quickly damaged by aging than the more frequently studied DNA. RNA

damage, therefore, could be an excellent early signal to indicate the

onset of aging, researchers say.

" Because it is more sensitive to oxidative stress, RNA can be useful

as an early marker of oxidative damage and even aging, " said Arnold Y.

Seo, a doctoral student in UF's Institute on Aging.

Seo authored the report along with Tim Hofer, Ph.D., an Institute on

Aging research associate.

" To avoid disease, we can increase our defense and look for aging

biomarkers and then test interventions, " Hofer said. " It is better to

protect what is there to improve the quality of life than to have to

resort to invasive procedures. "

In the study, which followed the rats over their lifespan, one group

of animals ate as much food as they wanted and did not exercise,

another group of animals exercised lightly and were fed slightly less

than they would have eaten if allowed to have their fill. Liver

samples from these groups were compared with samples taken from young

rats.

The old sedentary rats that ate until they were full had increased

levels of harmful oxidizing and inflammatory molecules in the liver

that were associated with cell damage caused by aging. Meanwhile,

aging rats that exercised and consumed a calorie-restricted diet, had

the reverse outcome - they showed a decrease in these molecules in the

liver.

Leeuwenburgh said the study results support the theory that cell death

and aging-related organ damage are caused by unstable molecules known

as free radicals and by cellular oxidation and inflammation.

" In a calorie-restricted environment, you reduce the inflammatory

response and prevent cell death, " Leeuwenburgh said.

O. Holloszy, a professor of medicine in the division of

geriatrics and nutritional sciences at Washington University School of

Medicine in St. Louis, said the study is of major importance because

it shows a mild degree of caloric restriction - just enough to prevent

weight gain with advancing age - can have beneficial effects against

aging. From a scientific perspective, he added, it is important to

learn that RNA is a very good marker of aging damage.

" I'd never really thought about RNA before, " Holloszy said. " Research

has always looked at DNA. Because RNA is the template for the

information on the genes on the DNA, RNA damage is a major problem

because it results in mutations in the transcription of proteins. "

Source : University of Florida