Naked mole-rat’s longevity secret cloaked in mystery

Naked mole-rat’s longevity secret cloaked in mystery

Scientists are studying the burrowing rodents, which live 10 times longer than mice and appear to be immune to cancer.
Scientists are studying the burrowing rodents, which live 10 times longer than mice and appear to be immune to cancer.
 

By Rita Rubin, USA TODAY 

They have a face only a naked mole-rat mother could love.

But what they lack in looks, those
so-ugly-they’re-cute naked mole-rats make up for in life span. One of
the wrinkled, blind and buck-toothed creatures, captured in the wild
when he was less than 1 year old, lived for more than 27 years in a lab
— 10 times longer than a mouse.

What’s their secret?

Researchers on aging would like to know.

Stan Braude, a Washington University
developmental biologist who has been studying them for more than a
quarter-century, says their longevity might be because they really know
how to chill. Not chill as in lowering their body temperature, but
chill as in lowering their metabolic rate.

Naked mole-rats can basically shut down their
metabolism when times get tough, such as when food is scarce. A
28-year-old naked mole-rat’s metabolism might have been revved up for
only a total of three or four years, says Braude, who’s working on a
book about the critters. (He already has written a children’s book
about a day in the life of naked mole-rats, although he hasn’t yet
found a publisher.)

If scientists could pinpoint the genetic or
biochemical mechanisms behind naked mole-rats’ long lives, perhaps they
could mimic it with medical treatments for humans, Braude says. "But
first you have to understand why some animals live longer than others,
not how."

Braude’s colleague, Rochelle Buffenstein, a
comparative biologist at the University of Texas Health Science Center
in San Antonio, isn’t convinced that naked mole-rats’ ability to
"pulse" their metabolism explains their longevity. Though their resting
metabolic rate is 30% lower than what you’d expect for an animal their
size, she says, they still expend more energy in their lifetime than
any other mammal.

Still, Braude and Buffenstein agree that naked mole-rats pretty much leave prevailing theories about aging in the dust.

One theory states that an organism either puts
all of its resources into reproducing or all of its resources into
maintaining its tissue. Either it has a lot of offspring and dies
young, Buffenstein says, or it breeds later and has fewer offspring.

But female naked mole-rats never enter a
"menopause," she says. They breed young, they breed old. "Our
most-established older breeders may have as many as 29 pups per
litter," she says, and may have more than 1,000 pups in their lifetimes.

Even so, Buffenstein says, a 24-year-old naked
mole-rat has the body of a 2-year-old. "We see almost no age-related
declines in any system, including cardiovascular, bone, cartilage,"
despite the fact that even youngsters have much more oxidative damage
than mice. In other words, they get rusty, but they still function fine.

On top of that, Buffenstein says, no one has
ever seen a naked mole-rat with cancer. "To put this into perspective,"
she says, "most mice will have some form of cancer by the time they are
2 years of age."

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