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URBANA, Ill. — Do you often extinguish a bad mood by taking a trip to the local gym? While it's hardly a secret that working out can improve both mental and physical health, new research reveals that exercise may also improve brain health in a more direct manner. Scientists at the Beckman Institute for Advanced Science and Technology report that the chemical signals released by exercising muscles promote neuronal development in the brain.
When our muscles contract during exercise, for example while lifting a heavy weight, numerous compounds enter the bloodstream. Those compounds are capable of traveling to various parts of the body, including the brain. Study authors placed a particular focus on how exercise may or may not benefit a specific part of the brain called the hippocampus.
“The hippocampus is a crucial area for learning and memory, and therefore cognitive health,” explains Ki Yun Lee, a Ph.D. student in mechanical science and engineering at the University of Illinois Urbana-Champaign and the study's lead author, in a media release.
Exercise literally sparks the brain!
A clearer understanding of how fitness benefits the hippocampus in particular could help produce new exercise-based treatments for a variety of conditions including Alzheimer’s disease. So, in order to isolate the chemicals released by contracting muscles and test them on hippocampal neurons, the research team gathered small muscle cell samples from a group of mice and grew them in cell culture dishes in their lab. Once the cells matured, they begun contracting on their own, releasing their chemical signals into the cell culture.
Next, researchers added the culture, which at this point contained the chemical signals from the mature muscle cells, to yet another culture containing hippocampal neurons as well as other support cells known as astrocytes. Using several different measures, including immunofluorescent and calcium imaging to track cell growth and multi-electrode arrays to record neuronal electrical activity, study authors were able to assess how exposure to these chemical signals affect the hippocampal cells.
The ensuing results were striking. Exposure to the chemical signals from contracting muscle cells caused hippocampal neurons to generate larger and more frequent electrical signals, considered a sign of robust growth and health. Over the following few days, the neurons began firing the electrical signals more synchronously. This suggests, researchers say, that the neurons were forming a more mature network together and mimicking the organization of neurons in the brain.
Scientists are still figuring out how this takes place
Still, the research team has a number of questions regarding how these chemical signals led to growth and development of hippocampal neurons. In an effort to better understand the pathway linking exercise to better brain health, they've chosen to focus their attention moving forward on the role of astrocytes in mediating this relationship.
“Astrocytes are the first responders in the brain before the compounds from muscles reach the neurons,” Lee explains, noting that it's possible they played a role in helping neurons respond to these signals.
Researchers also found that removing astrocytes from the cell cultures resulted in the neurons firing off even more electrical signals, suggesting that without the astrocytes, the neurons will continue to grow — perhaps even to a point where they might become unmanageable.
“Astrocytes play a critical role in mediating the effects of exercise,” Lee adds. “By regulating neuronal activity and preventing hyperexcitability of neurons, astrocytes contribute to the balance necessary for optimal brain function.”
In conclusion, study authors say shedding light on the chemical pathway between muscle contraction and the growth and regulation of hippocampal neurons is just the first step in understanding how exercise helps improve brain health.
“Ultimately, our research may contribute to the development of more effective exercise regimens for cognitive disorders such as Alzheimer's disease,” Lee concludes.
The study is published in the journal Neuroscience.
