What Hibernating Squirrels Can Teach Astronauts About Preventing Muscle Loss

The Arctic ground squirrel recycles nutrients in its body, allowing it to slumber for up to eight months and wake up unscathed

A person wearing blue lab gloves holds a hibernating squirrel in its hands. The squirrel has light brown fur and is curled up, deep asleep.
Arctic ground squirrels are such adept hibernators that they can remain in their slumber for up to eight months by slowing their metabolic system down so greatly that they only need to breathe once per minute. Carla Frare photo

When temperatures become too cold to endure, animals like bears, turtles, groundhogs, bats and squirrels slip into a deep state of hibernation to conserve precious energy. The body's temperature, heart rate and breathing slow, allowing the critters to wait out the frigid months in a deep slumber before awakening to warmer spring air.

To figure out how animals manage to hibernate for months on end, a team of scientists studied Arctic ground squirrels in a laboratory for two years. These squirrels are such adept hibernators that they can remain in their slumber for up to eight months by slowing their metabolic system down so greatly they only need to breathe once per minute, according to a press release.

In a study published Monday in the journal Nature Metabolism, a team of scientists discovered that these squirrels are able to do so by recycling nutrients in their bodies in order to survive, reports Tara Yarlagadda for Inverse.

As the squirrels' muscles start to slowly break down, their bodies take the nitrogen released from this process and recycle it into amino acids, the building blocks of proteins. As a result, they produce proteins used to build lung, kidney and skeletal muscle tissue, so they suffer less muscular loss, reports Chrissy Sexton for Earth.com.

Previous research suggested that animals recycle nitrogen, such as from urea—a nitrogen-heavy substance produced in the liver and excreted through urine—when they hibernate. This study is the first to observe the process in real-time, reports Harry Cockburn for the Independent.

Scientists have been trying to unravel how animals can hibernate for months and wake up mostly unscathed, but when people are bed-ridden or unable to walk, they can experience devastating side effects, such as muscle loss and cellular damage, in as little as a week. Figuring out how animals dodge these effects can help scientists develop treatments for the elderly and people with cancer, who are greatly affected by muscle loss, reports Earth.com.

Most research focuses on treating injuries or illnesses after they happen, but that's not the approach that lead author Sarah Rice, a biologist at the University of Alaska Fairbanks, chose to take.

"It's fun to kind of turn that idea on its head," Rice says in the press release. "Instead of studying what goes wrong in the world, it's important to study what goes right."

Beyond treating patients, this study also inches the science closer to discovering if hibernation can be induced in humans. It may seem far-fetched, but hibernating would allow humans to go months without moving, which could be a game-changer for astronauts who plan to voyage to Mars, a voyage that can take up to nine months, reports Inverse.

"A long-term goal is to mimic the metabolic adaptations in hibernation in humans," says co-author Kelly L. Drew, a biologist at the University of Alaska Fairbanks. "Towards this end, we need to know what metabolic processes contribute to the unique metabolic phenotype of hibernating animals, which this paper reveals."

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