Scientists extend lifespan of female mice and thwart diseases of old age in both sexes
THURSDAY, Oct. 1 (HealthDay News) -- In a possible advance toward a treatment for aging in people, researchers report that by genetically modifying mice, they reduced their susceptibility to age-related disease and expanded the lifespan of female mice by 19 percent.
Scientists have known for decades that taking in fewer calories can extend lifespan in some animals, but they have yet to figure out why that is so. In this new study, published in the Oct. 2 issue of Science, researchers manipulated mouse genes so they wouldn't produce a protein known as S6K1, thereby mimicking the effects of a strict diet.
No one knows if trying something similar in humans would slow their aging, and male mice didn't gain a longer lifespan. But researchers are hopeful, especially since the mice seemed to suffer no ill effects.
The mice were "in general, happier and healthier. We added life to their years as well as years to their lives," said study co-author Dr. Dominic J. Withers, a professor at University College London in England.
In essence, he explained, researchers have found a "mechanism" connected to the benefits of eating little that could be manipulated by existing medications. "We are therefore closer to treatments for aging and age-related diseases," he said.
At issue is finding a way to replicate the benefits of a severely restricted diet. But, keeping extremely tight control on eating can be "arduous" on a long-term basis, Withers acknowledged.
Female mice lived for an average of 950 days, 19 percent longer than usual, were skinnier and had stronger bones. They appeared to be better protected against type 2 diabetes and also appeared to be smarter: They were more "inquisitive and exploratory," Withers noted.
"Even their T cells, an important part of the immune system, appeared more 'youthful,' implying slowing of the usual age decline in immunity," he said.
The males didn't live longer but reaped other health benefits enjoyed by the females, Withers said, noting the cause of the lifespan difference is unclear.
Matt Kaeberlein, an assistant professor of pathology at the University of Washington in Seattle, said these and other new findings are shifting "the prevailing opinion among scientists working in this area [of life extension] from 'if' to 'when.'" That theory is supported by other recent life-extension research involving a drug called rapamycin and confirmation that diet restriction helps monkeys live longer, he noted.
"Most of us believe that anti-aging drugs are possible and are going to be developed from studies such as these," said Kaeberlein, co-author of a commentary accompanying the study.
So, what's next? Withers said a diabetes drug called metformin, which is marketed as Glucophage, Glumetza and Fortamet, might mimic the effects of the genetic engineering in the mice.
But, "it would take some time to work out if treating people with drugs based upon our studies actually has long-term health benefits," he said. "Clearly, undertaking such trials in humans would be a sensible next step."
The Stanford Center on Longevity has more on the myths and challenges of aging.
SOURCES: Dominic J. Withers, M.D., Ph.D., professor, University College London; Matt Kaeberlein, Ph.D., assistant professor of pathology, University of Washington, Seattle; Oct. 2, 2009, Science
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