Naked Mole Rat Defies Mammal Aging Process
When you think about which animal you’d consider to be a supermodel, the naked mole rat doesn’t spring to mind straight away. But, a new paper suggests that it most certainly is.
Combined with the fact that they rarely get cancer, they are resistant to some types of pain and can survive up to 18 minutes with oxygen, it has now been discovered that their risk of death doesn’t go up as they grow older like it does for every other known mammalian species, reports Science.
“This is remarkably low mortality,” explained Caleb Finch, a biogerontologist at the University of Southern California in Los Angeles who was not involved in the study. “At advanced ages, their mortality rate remains lower than any other mammal that has been documented.”
The new research answers a lot of long-thought questions from scientists, who have wondered why they show few signs of aging and far surpass the life-span expected of a rodent of this size for years.
Comparative biologist Rochelle Buffenstein has studied the animals for more than 20 years, and as a result, collected a lifetime’s worth of data. For each animal in her care, she recorded the date of birth and when it died, and whether it was killed for an experiment or given away to other researchers.
She was shocked by the results, after they had reached sexual maturity at 6 months of age, each naked mole rat’s daily chance of dying was more than one in 10,000. It stayed the same the rest of their lives and even went down a little. “To me, this is the most exciting data I’ve ever gotten,” she said. “It goes against everything we know in terms of mammalian biology.”
In the past, studies have shown that naked mole rats have very active DNA repair and high levels of chaperones, proteins that help other proteins fold correctly. “I think the animals keep their house really neat and clean, rather than accumulate damage” that causes the physical deterioration associated with age, suggests Buffenstein.
However, Finch warns of the problems associated with overinterpreting the data. Becuase most animals were either killed or moved to other lavs, fewer than 50 animals in the study lived past 15 years of age. He argues that older mole rats are needed to be sure that the risk of dying really is flat.
But, Buffenstein explained that the data doesn’t show the typical aging pattern seen in mammals or any other animals. “Ig you look at any rodent aging study, a hundred animals is all you need to see Gompertz aging,” she said. “Here we have 3000 data points and we’re not seeing it.”
The study isn’t ruling out the possibility of aging altogether, but it suggests it happens much later than in mammals instead, notes Pedro De Magalhaes, a gerontologist at the University of Liverpool in the United Kingdom. “I think it’s too early to say naked mole rats are nonaging mammals,” he explained.
Rather the mystery we should be trying to uncover now is what happens in naked mole rats after 20 or 30 years, suggests Mattias Platzer, a biologist at the Leibniz Institute on Aging in Jena, Germany.
“Maybe aging happens really fast then? Even Rochelle Buffenstein does not have the data on this,” he added. Nonetheless, he is very happy that the world’s largest and oldest lab colonies of naked mole rats are now widely available.