Wily bald underground critter uses plant-like survival strategy

WASHINGTON (Reuters) - They are homely, buck-toothed, pink, nearly hairless and just plain weird, but one of the many odd traits of rodents called naked mole-rats that live in subterranean bliss in the deserts of East Africa could someday be of great benefit to people.

Scientists said on Thursday the rodents, when deprived of oxygen in their crowded underground burrows, survive by switching to a unique type of metabolism based on the sugar fructose rather than the usual glucose, the only animal known to do so.

Metabolizing fructose is a plant strategy, and the researchers were surprised to see it in a mammal. They now hope to harness lessons learned from this rodent to design future therapies for people to prevent calamitous damage during heart attacks or strokes when oxygenated blood cannot reach the brain.

Naked mole-rats, they found, can survive up to 18 minutes with no oxygen and at least five hours in low-oxygen conditions that would kill a person in minutes.

More closely related to porcupines than moles or rats, they thrive in colonies boasting up to 300 members including a breeding queen in an insect-like social structure of cooperation in food-gathering and tunnel-digging. With all those rodents breathing and clogging up burrows, they often encounter low-oxygen and high-carbon dioxide conditions.

"Naked mole-rats have evolved in an extremely different environment from most other mammals and they have had millions of years to figure out how to survive dramatic oxygen deprivation," said neurobiologist Thomas Park of the University of Illinois at Chicago, who helped lead the study published in the journal Science.

In low-oxygen conditions, they enter a coma-like state and release fructose into the blood. By shifting their metabolism from the normal glucose-based system that relies on oxygen to a fructose-based system that does not, they can fuel vital organs such as the heart and brain.

Naked mole-rats live up to 30 years, decades longer than other rodents, are nearly immune to cancer and do not feel many types of pain. As the only cold-blooded mammal, they huddle together in mole-rat piles in order to keep warm. Their lips close behind their teeth so that they can dig with their teeth without getting dirt in their mouths. Their ears and eyes are tiny, and they have poor eyesight.

"Fructose has been linked to obesity and metabolic syndrome but that's because we over-consume it in sweet beverages and junk food. Perhaps there is a use, and an important one, for fructose in moderate doses after all," added molecular biologist Jane Reznick of the Max Delbrück Center for Molecular Medicine in the Helmholtz Association in Berlin.

(Reporting by Will Dunham; Editing by Sandra Maler)