Dec. 7 (UPI) -- By analyzing the body chemistry of hibernating Arctic ground squirrels, scientists found the rodents are able to recycle their body's own nutrients during deep hibernation.
The discovery, detailed Monday in the journal Nature Metabolism, may explain how mammals survive prolonged periods of inactivity during the winter, as well as offer insights into muscle loss in humans.
For the study, researchers at the University of Alaska Fairbanks monitored ground squirrels in a lab for more than two years. Using pulse isotopic tracing, scientists were able to track the movements of nearly undetectable levels of nutrients through the squirrels' bodies.
As the rodents slept away the winter, with temperatures just above freezing, the instruments observed the conversion of free nitrogen -- released by the animals' atrophying muscles -- into amino acids.
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Researchers suspect the squirrels are able to use the amino acids to synthesize proteins that can help buoy the health of lung and kidney tissue, as well as bolster skeletal muscle.
For eight months of the year, Arctic ground squirrels hibernate -- and they don't drink or eat. While in their hibernation state, they take a single breath per minute.
Despite remaining inactive for the majority of the year, longer than other mammals, the squirrels don't experience significant muscle loss or long-term cellular damage.
"They're just this extreme hibernator, and during the time they hibernate they don't eat, they don't drink, and they don't have any underlying injuries to their bodies," lead study author Sarah Rice, doctoral student at UAF's Institute of Arctic Biology, said in a news release.
Researchers have previously hypothesized that Arctic ground squirrels recycle urea, a nitrogen-rich waste product excreted in urine, but the latest study is the first to detect metabolic evidence of the phenomenon.
Authors of the new study suggest the biochemical secrets of hibernating animals could help researchers develop new treatments for muscle loss among cancer patients and the elderly.
The findings could also pave the way for better treatments for severe injuries, as well as preventative measures for astronauts, who often experience muscle atrophy in space.
