Studies in worms are shedding new light on the hormone's role in lifespan
THURSDAY, March 20 (HealthDay News) -- Scientists have gained new insight into the workings of insulin, potentially laying the groundwork for an anti-aging treatment.
The research has only taken place in worms, a common model for this type of research, and it's too early to know if it will translate to humans. But worms whose insulin levels were adjusted lived a week longer than their typical two-week lifespan, the scientists said.
"It doesn't sound like much for a worm, but those percentages would be a lot for us," noted study co-author Dr. T. Keith Blackwell, senior investigator at Harvard Medical School's Joslin Diabetes Center, in Boston.
According to Blackwell, the findings -- which explore a genetic pathway in the worms -- provide new information about how insulin and lifespan might be related.
"We're understanding more and more about how cellular processes can really influence how we defend ourselves against challenges from the environment," he said.
The new findings are published in the March 21 issue of the journal Cell.
Insulin is best known as the hormone that allows healthy people to regulate blood sugar and is linked to a variety of problems in diabetics.
Insulin has other jobs, such as helping to regulate the burning of fuel by cells to provide energy, noted Blackwell, an associate professor of pathology at Harvard Medical School and faculty member at the Harvard Stem Cell Institute. Insulin also serves as a taskmaster, telling cells to process glucose, suppress tumors and respond to the daily challenges that our bodies face, he said.
In the new study, researchers looked into the effects of changing insulin levels in a species of tiny worm known as Caenorhabditis elegans. The worm has long been used in cutting-edge genetics research -- in fact, hundreds of the critters survived the 2003 Space Shuttle disaster intact, although their tiny lifespans prevented them from appreciating their brush with death for very long.
The Joslin researchers found that more insulin results in less activity by a gene-regulating protein called SKN-1. So, by lowering insulin levels, the study authors were able to boost levels of the protein and make the worms live longer.
The mechanism at work here seems to relate to how well cells defend themselves against damage. "From just being alive, your body is creating its own free radicals that can cause damage," Blackwell explained. "Your body has its own antioxidant systems that clean up damage and protect you from damage. We were able to push the activity of that system upward and make the animals live longer."
Previous research has shown that insulin controls the activity of another protein, known as FOXO, that also regulates genes.
The potential impact on people with diabetes is unclear. Diabetics are unable to produce enough insulin: people with the rarer type 1 diabetes produce no insulin, while those with type 2 diabetes don't produce enough.
Blackwell believes that the research does hold hope for people with a variety of diseases. "We're understanding more about mechanisms that can be harnessed in a way that pushes back this tide of cellular damage," he said. "There's a lot of therapeutic potential to defend against chronic diseases and potentially expand lifespans."
There's more on insulin at the U.S. Food and Drug Administration.
SOURCES: T. Keith Blackwell, M.D., Ph.D., associate professor of pathology, Harvard Medical School, and senior investigator, Joslin Diabetes Center, Boston. March 21, 2008, Cell.
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