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https://phys.org/news/2017-04-naked-mole-rats-oxygen.html
April 20, 2017
Deprived of oxygen, naked mole-rats can survive by metabolizing fructose just as plants do, researchers report this week in the journal Science.
Understanding how the animals do this could lead to treatments for patients suffering crises of oxygen deprivation, as in heart attacks and strokes.
“This is just the latest remarkable discovery about the naked mole-rat—a cold-blooded mammal that lives decades longer than other rodents, rarely gets cancer, and doesn’t feel many types of pain,” says Thomas Park, professor of biological sciences at the University of Illinois at Chicago, who led an international team of researchers from UIC, the Max Delbrück Institute in Berlin and the University of Pretoria in South Africa on the study.
In humans, laboratory mice, and all other known mammals, when brain cells are starved of oxygen they run out of energy and begin to die.
But naked mole-rats have a backup: their brain cells start burning fructose, which produces energy anaerobically through a metabolic pathway that is only used by plants – or so scientists thought.
In the new study, the researchers exposed naked mole-rats to low oxygen conditions in the laboratory and found that they released large amounts of fructose into the bloodstream. The fructose, the scientists found, was transported into brain cells by molecular fructose pumps that in all other mammals are found only on cells of the intestine.
“The naked mole-rat has simply rearranged some basic building-blocks of metabolism to make it super-tolerant to low oxygen conditions,” said Park, who has studied the strange species for 18 years.
At oxygen levels low enough to kill a human within minutes, naked mole-rats can survive for at least five hours, Park said. They go into a state of suspended animation, reducing their movement and dramatically slowing their pulse and breathing rate to conserve energy. And they begin using fructose until oxygen is available again.
The naked mole-rat is the only known mammal to use suspended animation to survive oxygen deprivation.
The scientists also showed that naked mole-rats are protected from another deadly aspect of low oxygen – a buildup of fluid in the lungs called pulmonary edema that afflicts mountain climbers at high altitude.
The scientists think that the naked mole-rats’ unusual metabolism is an adaptation for living in their oxygen-poor burrows. Unlike other subterranean mammals, naked mole-rats live in hyper-crowded conditions, packed in with hundreds of colony mates. With so many animals living together in unventilated tunnels, oxygen supplies are quickly depleted.
More information: “Fructose-driven glycolysis supports anoxia resistance in the naked mole-rat,” Science (2017). science.sciencemag.org/cgi/doi/10.1126/science.aab3896
Naked mole rat found to defy Gompertz’s mortality law
January 30, 2018 by Bob Yirka, Phys.orghttps://phys.org/news/2018-01-naked-mole-rat-defy-gompertz.html
A team of researchers at Google-owned Calico Life Sciences LLC has found that the naked mole rat defies Gompertz’s mortality law. In their paper published in eLife, the group describes their study of the unusual-looking rodent and describe some of its unusual traits.
Naked mole rats are very nearly hairless. They evolved that way by living in a harsh underground environment. They are also almost ectothermic (cold blooded). And now, it seems they do not age—at least in the traditional sense. Reports of long-lived mole rats prompted the team at Calico to take a closer look—they have a specimen in their lab that has lived to be 35 years old. Most “normal” rats, in comparison, live to be just six years old, and they age as they do so.
Naked mole rats also have some other interesting biological features—they very rarely develop cancer, they experience very little pain and they have been found able to survive without oxygen for up to 18 minutes by going into a plant-like vegetative state. Also, they never reach menopause, and can have offspring right up until their death—and their hearts and bones never show signs of aging. But it was their longevity that was the focus of this new effort.
The team collected what they describe as 3,000 points of data regarding the lifespan of the naked mole rat, and found that many had lived for 30 years. But perhaps more surprisingly, they found that the chance of dying for the mole rats did not increase as they aged. All other mammals that have been studied have been found to conform to what is known as Gompertz’s mortality law, which states that the risk of death for a typical mammal grows exponentially after they reach sexual maturity—for humans, that means the odds of dying double every eight years after reaching age 30. This, the researchers claim, suggests that mole rats do not age—at least in the conventional sense. They do eventually die, after all.
The research team concludes by suggesting that a lot more work needs to be done with naked mole rats to find out if they are aging, but are doing so very slowly. Most captive mole rats, they note, are killed for research purposes, so there is little good data on how long they actually live.
More information: J Graham Ruby et al. Naked mole-rat mortality rates defy Gompertzian laws by not increasing with age, eLife (2018). DOI: 10.7554/eLife.31157
Abstract
The longest-lived rodent, the naked mole-rat (Heterocephalus glaber), has a reported maximum lifespan of >30 years and exhibits delayed and/or attenuated age-associated physiological declines. We questioned whether these mouse-sized, eusocial rodents conform to Gompertzian mortality laws by experiencing an exponentially increasing risk of death as they get older. We compiled and analyzed a large compendium of historical naked mole-rat lifespan data with >3000 data points. Kaplan-Meier analyses revealed a substantial portion of the population to have survived at 30 years of age. Moreover, unlike all other mammals studied to date, and regardless of sex or breeding-status, the age-specific hazard of mortality did not increase with age, even at ages 25-fold past their time to reproductive maturity. This absence of hazard increase with age, in defiance of Gompertz’s law, uniquely identifies the naked mole-rat as a non-aging mammal, confirming its status as an exceptional model for biogerontology.Journal reference: eLife
https://en.wikipedia.org/wiki/Gompertz%E2%80%93Makeham_law_of_mortality
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