Blood plasma of sleeping bears will protect our muscles from degradation during immobility

(ORDO NEWS) — Treatment of muscle cells with plasma obtained from hibernating bears stimulated their activity and growth, although biologists have not been able to determine which protein triggers these processes.

Japanese biologists have shown that blood plasma obtained from hibernating bears enhances the metabolism of human muscle cells, while plasma taken during the normal period does not have such an effect.

Scientists suspect that a certain protein that accumulates during hibernation stops the processes leading to degradation and atrophy of muscle tissue. However, so far it has not been possible to isolate this “active substance”.

Hibernation in bears lasts 5-7 months, and all this time the huge animals do not drink, eat or move. However, with the onset of heat, they crawl out of their dens and immediately go in search of food.

By comparison, in humans, muscle degradation begins as early as three weeks of immobility, and a lack of activity for longer periods is fraught with the development of obesity, diabetes and other serious health problems.

Bears, on the other hand, maintain a healthy, albeit sharply slowed, metabolism, and good muscle condition during the months of winter hibernation.

Indeed, in most mammals, skeletal muscle follows the “use it or loose it” rule. This allows the body to flexibly adapt to external conditions: muscles that are not loaded quickly weaken, and those that tense regularly, on the contrary, develop.

This effect is associated with constant competition between opposing biological mechanisms, one of which stimulates the destruction of muscle tissue, and the other stimulates its synthesis.

Animals that hibernate do not follow the “use it or lose it” rule and are able to retain muscle even without using it for a significant amount of time. How this happens is still largely unknown.

One of the tools for such protection can be as yet unidentified proteins that circulate in the blood and properly affect the destruction and production of muscle tissue. This was also confirmed by new experiments carried out by the team of Professor Mitsunori Miyazaki.

Biologists took blood from hibernating Japanese black bears and purified it from cells, obtaining plasma full of proteins and other molecules. It was treated with cultures of human muscle cells that were grown “in vitro”, and after a few hours they showed a significant increase in activity.

At the same time, the same cells, treated with plasma obtained from bears during the period of normal summer activity, continued to grow as before.

Scientists attribute the positive effects of bear plasma in hibernation to a decrease in the synthesis of the MuRF1 protein , which triggers the mechanisms of muscle atrophy.

This, in turn, may be associated with the activation of the Akt/FOXO3 signaling pathway , which stimulates cellular metabolism. However, it has not yet been possible to trace the chain further and determine the specific plasma protein that triggers these processes.

“We have found that during the hibernation period, there is a factor in the blood plasma of bears that can stimulate the metabolism of human muscle cells and maintain the preservation of muscle mass,” says Miyazaki.

“If we identify it and figure out the unknown mechanism by which muscles in animals in hibernation are preserved even without exercise, then we can develop effective rehabilitation strategies for humans and stop suffering from a lack of mobility in the future.”


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