Metabolizing
fructose to produce energy anaerobically through a specific metabolic
pathway is a process that scientists previously thought was only used by
plants. Not so, says new research.
Naked mole-rats can survive low-oxygen conditions that in all other
mammals would normally result in brain cell death, by making a switch
from a glucose-based system that depends on oxygen, to one where their
brain cells start burning fructose.
“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,” study
leader, Thomas Park, professor of biological sciences at the University
of Illinois at Chicago, said in a statement.
For the study, published this week in
Science,
naked mole-rats were exposed to low oxygen levels in the lab, and
researchers observed that large amounts of fructose was released into
the bloodstream. Molecular fructose pumps, which are only found on cells
of the intestine in all other mammals, transport the fructose into the
naked mole-rats brain cells.
Park has studied the interesting creature for 18 years and said: “The
naked mole-rat has simply rearranged some basic building-blocks of
metabolism to make it super-tolerant to low oxygen conditions.”
The animals go into a state of suspended animation and can even live
through 18 minutes of total oxygen deprivation. When they go into the
suspended animation state, their breathing slows dramatically, as well
as their heart rate, which drops from 200 to about 50 beats per minute.
They are the only mammals known to employ this method for survival of
oxygen deprivation.
Once oxygen becomes available, they resume normal activity with no signs of lasting damage.
Naked mole-rats can survive for at least five hours in low oxygen levels that would kill a human within minutes, Park said.
The animal is also able to avoid deadly pulmonary edema, which is a
buildup of fluid in the lungs due to lack of oxygen that often affects
high altitude mountain climbers.
Naked mole-rats live underground in densely populated conditions with
hundreds of colony mates. The researchers hypothesize that the naked
mole-rat may have developed this survival mechanism as an adaptation to
its living situation.
Deeper understanding as to how the animals manage this feat
could
have implications for treating patients experiencing oxygen deprivation
such as in heart attacks and strokes.
