Engineers at the Massachusetts Institute of Technology (MIT) in the US have discovered that exercise can also have benefits at the level of individual neurons. They observed that when muscles contract during exercise, they release biochemical signals called myokines.
In the presence of these muscle-generated signals, neurons grew four times more than neurons that were not exposed to myokines. These experiments at the cellular level suggest that exercise can have a significant biochemical effect on nerve growth.
Surprisingly, the researchers also found that neurons respond not only to the biochemical signals of exercise, but also to its physical impact. The team observed that when the neurons are repeatedly pulled back and forth, similar to how muscles contract and expand during exercise, the neurons grow as much as when exposed to a muscle’s myokines .
While previous studies have indicated a possible biochemical link between muscle activity and nerve growth, this study is the first to show that physical effects may be just as important, the researchers say.
“Now that we know there’s this interconnection between nerves and muscles, it can be useful for treating things like nerve damage, where the communication between nerves and muscles is interrupted,” says Ritu Raman, an assistant professor of mechanical engineering at MIT for developing Eugene Bell’s career.
Muscles release biochemical signals
In their new study, the team set out to determine whether muscle exercise has any direct effect on how nerves grow, focusing exclusively on muscle and nerve tissue.
The researchers grew mouse muscle cells into long fibers that then joined together to form a small sheet of mature muscle tissue about the size of a quarter. The team genetically engineered the muscle to contract in response to light. With this modification, the team was able to turn on a light repeatedly, causing the muscle to contract in response, in a way that mimics the act of exercise.
Raman previously developed a new gel mat on which to grow and train muscle tissue. The properties of the gel are such that it can support muscle tissue and prevent it from tearing when the researchers stimulated the muscle to exercise, they write EurekAlert.
The team then collected samples from the surrounding solution in which the muscle tissue was trained, figuring that the solution should contain myokines, including growth factors, RNA and a mixture of other proteins.
The team transferred the myokine solution to a separate vessel containing the motor neurons—nerves found in the spinal cord that control the muscles involved in voluntary movements. The researchers grew the neurons from stem cells from mice. As with muscle tissue, neurons were grown on a similar gel mat.
A direct effect on how nerves grow
After the neurons were exposed to the myokine mixture, the team noticed that they began to grow rapidly, four times faster than neurons that did not receive the biochemical solution. To take a closer look at how the neurons changed in response to the exercise-induced myokines, the team performed a genetic analysis, extracting RNA from the neurons to see if the myokines induced any changes in the expression of certain neuronal genes.
The results suggest that the biochemical effects of exercise may promote neuron growth. The researchers grew a different set of motor neurons on a gel mat that they embedded with small magnets. They then used an external magnet to move the carpet – and the neurons – back and forth. In this way, they “exercised” the neurons, for 30 minutes a day. To their surprise, they found that this mechanical exercise stimulated the neurons to grow as much as the myokine-induced neurons, growing significantly more than neurons that received no form of exercise.
Now that the group has shown that muscle exercise can promote nerve growth at the cellular level, they plan to study how specific muscle stimulation can be used to grow and heal damaged nerves and restore mobility in people with neurodegenerative disease.
We recommend you also read:
Only 3 types of neurons are responsible for appetite, suggests a study in mice
Sleep resets neurons for new memories
A new nasal spray for Alzheimer’s removes toxins from neurons
Neurons “predict” the future even while we sleep
Source: www.descopera.ro
