A new study reveals how exercise enhances brain function by investigating the role of nerves in muscle-brain communication. The study, published in the Proceedings of the National Academy of Sciences, shows that muscles release molecules that support brain cell communication and development, and that this release is driven in part by signals from nerves that tell muscles to move. revealed. These findings help clarify the complex relationship between exercise, muscle function, and brain health.
Previous research has proven that when muscles are activated during physical activity, they release molecules that travel through the bloodstream and positively impact brain cells. These molecules, such as vesicles containing hormones and RNA, help brain cells form stronger connections and communicate more efficiently.
However, the role of nerves in causing muscle movement during this process was not well understood. As we age or due to injury or disease, we tend to lose nerve connections to our muscles. This reduction in nerve supply can cause muscle breakdown and lead to widespread organ dysfunction, including the brain.
The researchers aimed to investigate how nerve signals to muscles affect the release of molecules that support brain function. They wanted to better understand the mechanisms of this muscle-brain communication and identify ways to maintain or strengthen this connection, especially for older adults and people with neuromuscular diseases. If successful, their findings could provide the basis for developing treatments that target muscle-brain interactions, allowing people to maintain cognitive function despite loss of muscle mass and neural connections. There is a possibility that it can be done.
To investigate the role of neural signals in muscle-brain transmission, the researchers created two different models of muscle tissue. One contains nerve cells and the other does not. This allowed them to compare the two and determine how the presence of nerves affects the muscles’ ability to release molecules that strengthen the brain.
They placed the muscle in a laboratory dish and received nerve cells into tissue groups there, allowing the muscle and nerve cells to form connections similar to those that occur in the body. These nerve and muscle connections are known as neuromuscular junctions. The second group of muscle tissue had no nerve cells. After establishing these two groups, the researchers used glutamate, a neurotransmitter that transmits signals to the brain and nervous system, to stimulate the muscles connected to the nerves to determine the magnitude of the stimulation the muscles receive during exercise. imitated the type.
The researchers then measured the amount and type of molecules released from the muscles into surrounding body fluids. They focused on two types of molecules in particular. One is hormones like irisin, which are known to have beneficial effects on the brain, and the other is extracellular vesicles, small particles that carry RNA and other molecular cargo between cells.
In addition to measuring the overall amount of molecules, the team also looked at the specific types of RNA found within the vesicles. Because these RNA fragments can affect brain cell development and communication.
This study revealed several important findings. First, muscle tissue connected to nerves released significantly more molecules beneficial to the brain than muscles without nerves. Specifically, muscles connected to nerves produce more of the hormone irisin, which is thought to be associated with the positive effects of exercise on brain health. Irisin has been shown to support brain function by crossing the blood-brain barrier and promoting neurogenesis, the process by which new brain cells are formed.
In addition, nerve-connected muscles also released a greater variety of extracellular vesicles carrying RNA fragments associated with brain development and neuronal communication. These vesicles are particularly important because they can transport molecular signals that help brain cells form stronger connections and communicate more effectively.
When the researchers stimulated the nerve-connected muscles with glutamate, they observed an even greater increase in the release of irisin and extracellular vesicles. In this stimulated group, the RNA fragments found within the vesicles were more diverse, and neural signals to the muscles not only increased the amount of molecules released but also increased the complexity of cargo molecules and It suggests that it will be more beneficial for the function.
These findings highlight the important role that neural signals play in facilitating muscle-brain communication. As muscles lose neural connections due to age or injury, their ability to release these brain-supporting molecules decreases, which can lead to cognitive decline and other brain-related problems.
Although this study provided new insights into the role of neurons in muscle-brain communication, it had several limitations. First, the experiments were conducted using muscle tissue grown in the lab. Although muscle tissue is useful in isolating certain factors, it does not fully reproduce the complex environment of an organism. Future research will need to test whether these findings also apply to live animals and, eventually, humans.
The researchers now plan to investigate the exact mechanisms at the nerve-muscle cell junction. They hope to determine whether nerve impulses directly influence the production of brain activating factors, or whether they primarily regulate their release. This knowledge could help develop targeted therapies for people with neuromuscular diseases and age-related muscle loss.
The research team also aims to use muscle models in the lab as a platform to efficiently produce molecules that are beneficial to the brain. By simulating exercise in the lab, researchers can better understand how to stimulate the release of these molecules, leading to novel studies that mimic the benefits of exercise in people who are unable to be physically active due to injury or illness. The hope is that this may pave the way to a cure. .
The study, “Neural innervation regulates the secretion of neurotrophic myokines and exosomes from skeletal muscle,” was conducted by Kai-Yu Huang, Gaurav Upadhyay, Yujin Ahn, Masayoshoi Sakeakura, Gelson J. Pagan-Diaz, Younghak Cho, and Amanda Written by C. Weiss. , Chen Huang, Jennifer W. Mitchell, Jaffei Li, Yang-Chi Tan, Yuheng Deng, Austin Ellis Mohr, Ji Dou, Xiaotein Zhang, Sehong Kang, Chen Chen, Jonathan V. Swee Doler, Song Gap Yim, Rasheed Bashir, Heechong Chung, Gabriel Popescu, Martha U. Gillette, Mattia Gazzola, and Gong Hyun-jun.
