Keeping a healthy weight may help people live longer by limiting brain exposure to insulin, say US scientists.
A study in mice found that reducing insulin signals inside brain cells increased lifespan.
Writing in Science, the researchers said a healthy lifestyle and weight reduce insulin levels in humans and may have the same effect.
Experts said, if proven, insulin would be just one of many factors, such as genes, that influence longevity. Previous research in fruit flies and roundworms has suggested that reducing the activity of the hormone insulin, which regulates blood sugar levels, can increase lifespan.
The latest study looked at the effects of a protein, IRS2, which carries the insulin signal in the brain.
Mice who had half the amount of the protein lived 18% longer than normal mice.
Despite being overweight and having high levels of insulin, the mice were more active as they aged, and their glucose metabolism resembled that of younger mice.
The researchers said the engineered mice were living longer because the diseases that kill them, such as cancer and cardiovascular disease, were being postponed due to reduced insulin signalling in the brain, even though circulating levels of insulin were high.
They said, in the future, it may be possible to design drugs to reduce IRS2 activity to reproduce the same effect, although they would have to be specific to the brain.
Source - BBC