Healthcare (Commonwealth Union) – Exercise undeniably benefits the body, enhancing not just muscle strength but also improving the health of bones, blood vessels, and the immune system. Now, researchers at MIT have discovered that physical activity can also positively influence individual neurons. Their experiments revealed that contracting muscles release a mix of biochemical signals, known as myokines, which significantly boost neuron growth. In fact, neurons exposed to these myokines grew four times farther than those without this exposure, highlighting the profound impact of exercise on nerve cell development.
Interestingly, the study also found that neurons respond to the mechanical effects of exercise. When subjected to repeated stretching and compressing—mimicking the physical movement of muscles during exercise—neurons grew just as much as they did in the presence of myokines.
While earlier research suggested a biochemical link between muscle activity and nerve growth, this is the first study to demonstrate that physical forces are equally important. Published in Advanced Healthcare Materials, the findings offer new insights into the interaction between muscles and nerves during exercise and could pave the way for therapies targeting nerve repair.
Ritu Raman, the Eugene Bell Career Development Assistant Professor of Mechanical Engineering at MIT indicated that this muscle-nerve communication could be leveraged for treating nerve injuries where the connection between muscle and nerve is disrupted.
She further indicated that stimulating the muscle might promote nerve healing, potentially restoring mobility for individuals with traumatic injuries or neurodegenerative conditions.
Raman led the study, working with MIT researchers Angel Bu, Ferdows Afghah, Nicolas Castro, Maheera Bawa, Sonika Kohli, Karina Shah, Brandon Rios, and Vincent Butty from the Koch Institute for Integrative Cancer Research.
In 2023, Raman and her team demonstrated a breakthrough in restoring mobility in mice with traumatic muscle injuries. Their approach involved implanting muscle tissue at the injury site and using light stimulation to repeatedly exercise the graft. Over time, this exercised tissue enabled the mice to recover motor function, eventually achieving activity levels similar to those of healthy mice.
Upon examining the graft, the researchers discovered that consistent exercise prompted the muscle tissue to release specific biochemical signals. These signals are known to encourage the growth of nerves and blood vessels, further highlighting the regenerative potential of their method.
“That was interesting because we always think that nerves control muscle, but we don’t think of muscles talking back to nerves,” explained Raman. “So, we started to think stimulating muscle was encouraging nerve growth. And people replied that maybe that’s the case, but there’s hundreds of other cell types in an animal, and it’s really hard to prove that the nerve is growing more because of the muscle, rather than the immune system or something else playing a role.”
In their latest research, the team aimed to explore whether exercising muscles directly influences nerve growth by concentrating exclusively on muscle and nerve tissues. They cultivated mouse muscle cells, which developed into elongated fibers that eventually fused to create a small sheet of mature muscle tissue about the size of a coin.
The researchers genetically engineered the muscle to contract when exposed to light. This innovation allowed them to simulate exercise by flashing light repeatedly, causing the muscle to contract in response. Raman had previously designed a specialized gel mat to grow and “exercise” muscle tissue. The gel’s unique properties ensured it could securely support the muscle tissue, preventing it from detaching during the exercise stimulation.
To carry out further investigations, the team collected samples from the solution surrounding the exercised muscle tissue. They hypothesized that this solution would contain myokines, including growth factors, RNA, and a variety of other proteins.
Researchers of the study have also expressed optimism of the findings for neurodegenerative diseases such as ALS.
