Bears Might Hold the Secret to Preventing Muscle Loss

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A hibernating bear is an impressive thing. That grizzly isn’t just down for a big sleep, after all; bears spend around four months a year hibernating, during which their metabolism and heart rate slow to a crawl. During those four months they barely move, yet when they awaken, they quickly get back up to speed, with no lasting side effects.

It’s a physical feat humans can’t accomplish—we need help just getting back into the groove after a winter “hibernation” of Christmas parties and egg-nog sloth. But scientists think we could learn something from studying bears: specifically, how they can spend all that time virtually motionless without their muscles atrophying.

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Researchers have begun studying samples of muscle tissue obtained from bears, both during and between hibernation. They wanted to see how genes and proteins worked differently during hibernation; because scientists haven’t yet charted all bear genes and proteins, it was a bit like surveying a landscape without a map. They also compared their findings with observations of humans, mice, and nematode worms (which can survive years in frozen environments).

The study found that proteins in bears made their bodies produce more non-essential amino acids (NEAAs) during hibernation. NEAAs are known to stimulate cell growth in muscle cells from humans and mice, but experiments show that simply giving patients amino acids in pills or powders doesn’t prevent muscle atrophy. It seems important that the muscles themselves produce the NEAAs.

So scientists also looked at what genes might be in play during hibernation, then focused specifically on muscle atrophy. They’ve narrowed their search down to a handful of genes, including a pair related to glucose and amino acid metabolism, and one associated with circadian rhythms, the body’s internal clock. While the research is in its early stages, figuring out how bears can sleep for months without losing muscle may turn out to be key to understanding how to prevent muscle loss in elderly or bedridden humans.



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