A new study proved that naked mole rats can survive at least 18 minutes without oxygen, a considerable feat for any mammal.
Lead researcher Thomas Park from the University of Illinois, Chicago, and Gary Lewin from the Max Delbrück Center for Molecular Medicine, Berlin, tested oxygen deprivation resistance in naked mole rats versus mice.
The subjects were put in an enclosed chamber without oxygen. The mice did not live longer than four minutes, contrary to the naked mole rats, which slowed their heart rate to 50 beats per minute and eventually lost consciousness. Minutes later, the naked mole rats were exposed to normal air, which allowed them to recover.
A metabolism designed for living underground
Researchers believe that naked mole rats can accomplish this by changing their primary source of energy, allowing them to rely on fructose rather than oxygen. It seems that they developed this mechanism because they tend to live in underground colonies alongside 300 other rats, making oxygen scarce.
When there is little oxygen, the body is not able to metabolize sugar correctly, a process known as glycolysis. If glycolysis does not occur, the body runs out of energy and brain cells rapidly begin to die.
“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,” stated Park according to Xinhua.net
Naked mole rats appear to perform glycolysis using fructose as fuel if there is no oxygen available. Researchers noted this when analyzing the blood of the specimens, which contained a high degree of sucrose and fructose. They also had a significant amount of a particular molecule that transports fructose into cells, and another enzyme that modifies fructose so it can be used in glycolysis.
Besides being able to live for several minutes without oxygen, the metabolism of naked mole rats also helps them prevent cancerous tumors. Researchers compared them to mice, which have a lifespan of 4 years and are susceptible to tumors. This is because the cells of naked mole rats are covered by a sugar coating called hyaluronan, which is also responsible for the rats’ skin elasticity.
“Our work is the first evidence that a mammal switches to fructose as a fuel. Patients who suffer an infarction or stroke experience irreparable damage after just a few minutes of oxygen deprivation. Theoretically, very few changes might be needed to adopt this unusual metabolism,” stated Lewin.
Switching to fructose could help prevent strokes and heart attacks, as oxygen deprivation causes the neuronal damage. If there’s any way to mimic the fructose pathway in humans, the time span between the cardiovascular disease event and the moment when brain cells begin to die.
According to Park, on the naked mole rats’ evolutionary process, they obtained a metabolism that was surprisingly resistant to low oxygen conditions. When such conditions are at hand, they would go into a state of suspended animation, slowing their pulse, breathing rate, and movement to save energy.
Source: Science Magazine