Hibernating grizzly bears hold the key to stopping muscles wasting away in humans

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Hibernating grizzly bears could shed light on how to reduce muscle wastage of astronauts in microgravity and patients on life support

  • Humans that do not use their muscles very often quickly see their muscles waste
  • This includes bedridden patients and astronauts that are in space  
  • But grizzly bears can hibernate for six months and maintain muscle size and tone
  • Scientists are now hoping to see if they can take the secrets from the genes of the grizzly bear and use it as a therapy for humans  

By Joe Pinkstone For Mailonline

Published: | Updated:

Hibernating grizzly bears may hold the key to preventing muscle wasting away in humans, offering new hope to bedridden patients and astronauts in space. 

Humans, like all animals that remain awake all year round, see their muscles enter atrophy – a wasting process which diminishes the tissue – if unused for long periods. 

This is a particular concern for patients in intensive care who are breathing via a ventilator, as the diaphragm begins wasting away within hours.  

But hibernating animals, including the vicious grizzly bear, can lie dormant for several months during the winter, and still maintain their muscle size and tone. 

Scientists have begun unpicking the secrets behind this phenomenon and have found a handful of genes and processes which may help stave off muscular atrophy. 

They are now hoping to turn their findings into medicine to help people prone to atrophy. 

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But hibernating animals, including the vicious grizzly bear, lay dormant for several winter months and maintain their muscle size and tone. The secret to this could lie in their genes as cells create non-essential amino acids that encourage cell growth to preserve muscle 

WHAT IS HIBERNATION?  

Hibernation is a mechanism employed by many animals to help them survive cold weather. 

Throughout winter months temperatures dip, food is scarce and survival can be difficult. 

Hibernation is different depending on the species but all awaken in the spring when temperatures recover again.  

A hibernating animal’s metabolism slows and its temperature plunges, this helps conserve energy and resources. 

Breathing slows as well and in some animals, so does the heart rate.  

Some cold-blooded animals, such as wood frogs, produce natural antifreezes to survive being frozen solid. 

mammals entering hibernation must store up large amount of fat by eating considerably in the weeks approaching hibernation, 

This layer of extra fat allows them to survive hibernation – insufficient fat reserves can result in starvation during hibernation. 

People unable to activate and use their muscles for long periods of time quickly enter into atrophy, including astronauts in space. 

When in space, on the ISS for example, the lack of gravity means muscles barely have to work and astronauts have a vigorous exercise routine to stop them from losing large amounts of muscle mass. 

It is a significant obstacle facing future space exploration missions, including planned manned missions to Mars.  

But grizzly bears, a large mammal that hibernates for around six months, emerges from its prolonged slumber with no noticeable loss in muscle size. 

Scientists have long sought to unlock the reasons behind this remarkable preservation and academics at the Max Delbrück Center for Molecular Medicine in Berlin published a paper in the journal Scientific Reports investigating the phenomenon. 

‘Muscle atrophy is a real human problem that occurs in many circumstances. We are still not very good at preventing it,’ says the lead author of the study, Dr Douaa Mugahid. 

Muscle samples were taken from four captive bears courtesy of researchers at Washington State University and assessed. 

Researchers were specifically searching for signs of heightened activity in muscle cell genes which produce proteins. 

Proteins are key in sustaining muscle growth and recovery and their building blocks, amino acids, are thought to be the key to the process. 

When in space, on the ISS for example, the lack of gravity means muscles barely have to work and astronauts have a vigorous exercise routine to stop them from losing large amounts of muscle mass (file)

When in space, on the ISS for example, the lack of gravity means muscles barely have to work and astronauts have a vigorous exercise routine to stop them from losing large amounts of muscle mass (file) 

The study revealed that some proteins in the muscles alter how a bear processes these amino acids during hibernation. 

They alter the metabolism of the grizzly and this ensures the muscle cells contain higher amounts of certain non-essential amino acids (NEAAs).

Researchers think these NEAAs could be the key to stopping atrophy over time but taking them as pills has already been proved ineffective. 

The muscle must be forced to produce it itself to make sure the NEAAs reach the right place and can work properly.

This field of research is completely untested and scientists are now hoping to find out if certain pathways can be activated to start the process. 

A handful of promising genes were discovered and are now being scrutinised to see if they have therapeutic possibilities. 

‘We will now examine the effects of deactivating these genes,’ says Michael Gotthardt, who led the research. 

 ‘After all, they are only suitable as therapeutic targets if there are either limited side effects or none at all.’  

WHY DO ASTRONAUTS WORKOUT IN SPACE, AND WHAT EXERCISES DO THEY DO?

In microgravity, body fluids are moved around. Fluids such as plasma are lost throughout the body. Plasma is where red blood cells live. 

Less plasma means there is less blood to carry oxygen to the rest of the body. 

Exercise, however, has been shown to increase the amount of plasma in the body. Astronauts who exercise make more red blood cells.

Microgravity also brings about another change in something called orthostatic intolerance. 

When you stand up quickly and feel light-headed – that’s orthostatic intolerance.

Your body tries to stop this from happening. It does so by increasing its heart rate and blood pressure to keep more blood returning to your heart. 

If you can’t do that, you’ll pass out. With no gravity and less blood volume, astronauts are more prone to fainting. 

Again, exercise can help increase blood volume and circulation. That helps prevent fainting.

While in space, astronauts must exercise two hours a day to prevent bone and muscle loss. 

Weakened astronauts would be less able to do tasks while in space. If there were an emergency, they would also need to be in good shape to get out of a space craft or station quickly. 

Once they land on Earth, weakened muscles and bones would make walking difficult.

Muscle can be built back up with therapy. But lost bone is not as easy to get back.

Three main exercises in space:

Astronauts use three pieces of exercise equipment. 

  • Cycle Ergometer: This is like a bicycle, and the main activity is pedaling. It is used to measure fitness in space because it’s easy to check heart rate and how much work is being done.
  • Treadmill: Walking or jogging on the treadmill is like walking on Earth. Walking is the single most important way to keep bones and muscles healthy. Because the lack of gravity tends to make people float, harnesses are attached to the astronauts to hold them to the walking surface. 
  • Resistance Exercise Device (RED): The RED looks like weight-lifting machines you may see on television. To use it, astronauts pull and twist stretchy rubber-band-like cords attached to pulleys. The RED can be used for a total body workout. From squats and bending exercises for the legs, to arm exercises and heel raises, astronauts can do them all on the RED. Russians and Americans have different exercise routines on the Space Station. But they all have the same goal: keeping the astronauts and cosmonauts healthy. 

Source: NASA