Naked mole rats are very interesting animals that live under extreme conditions, and they have a unique coping mechanism. Researchers have learned that when deprived of oxygen these creatures will begin to metabolize fructose, like plants do, in order to survive. The work may aid in treatments for heart attacks and strokes, situations in which people are faced with a critical lack of oxygen; it has been reported in the journal Science, and is outlined in the following video.
"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," explained Thomas Park, a Professor of Biological Sciences at the University of Illinois at Chicago, who led an international collaboration that included the Max Delbrück Institute in Berlin and the University of Pretoria in South Africa.
The brain cells of mammals like mice and humans are known to become depleted of energy and die off when they don’t get any oxygen. In the case of the unusual naked mole rat however, their brain cells will turn to fructose for energy by taking advantage of a chemical pathway that had previously only been known to exist in plants.
The investigators placed the animals in an environment with low levels of oxygen, and then discovered that they were releasing lots of fructose into the bloodstream. The researchers determined that molecular fructose pumps in the brain were importing the sugar into the brain. Those pumps are normally only found in intestinal cells in other mammals.
"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 worked with this intriguing animal for 18 years.
Park noted that these animals can live in a state of suspended animation when confronted with these extreme conditions. They are able to survive for hours in conditions that would kill other mammals, including people, within minutes. Their movement slows and their pulse and breathing rate drops. Then they start to use fructose for energy until oxygen is returned to their environment.
The investigators believe that the rats’ living conditions, underground in burrows, is the cause for these unusual abilities. The animals are also protected from pulmonary edema that can be seen in high-altitude climbers.
This work could have interesting applications. "Our work is the first evidence that a mammal switches to fructose as a fuel," commented Gary Lewin of UIC. He wants to know if human cells might also be pushed to these extremes. "Patients who suffer an infarction or stroke experience irreparable damage after just a few minutes of oxygen deprivation," he said. "Theoretically, very few changes might be needed to adopt this unusual metabolism."
Sources: AAAS/Eurekalert! via UIC, Max Delbrück Center of Molecular Medicine, Science