Along with a good diet, physical activity is known as a way to maintain or boost good health, particularly cardiovascular health. Exercise is also known to have many beneficial impacts on the brain. It's been suggested that older adults who get the recommended amount of exercise have a 20 percent reduction in the risk of cognitive decline and dementia. A new study has revealed one way that exercise could be improving brain health. Reporting in Neuroscience, researchers determined that during exercise, muscles release molecules that seem to encourage neuronal growth in the brain.
During exercise, muscles contract and release chemicals into the bloodstream that can move to different places in the body. The researchers were interested in how these chemicals might affect a region of the brain called the hippocampus, which is known to play an important role in learning, memory, and cognition.
In this study, the researchers used a mouse model in which samples of small muscle cells were taken while the muscles were contracting. These muscle cells were grown in culture, and once they matured, they could contract on their own, releasing various molecules that they generated into the culture media.
This culture media was then added to another culture of hippocampal neurons and astrocytes, a neuronal cell type that plays a variety of important roles in the brain. Several methods were used to assess the electrical activity and growth of these cells as they were exposed to the chemicals generated by muscles during exercise.
The work revealed that the hippocampal neurons got bigger and sent electrical signals more frequently, which is a sign of neuronal health, noted the researchers. The neurons in culture began to fire with more coordination within a few days; that could indicate the formation of a mature network, which would mimic how neurons are organized in the brain.
When the scientists removed astrocytes from this culture system, they found that the neurons fired more signals compared to neurons growing with astrocytes. This may indicate that without astrocytes, the neurons would keep growing and might eventually become unmanageable.
Astrocytes appear to have a crucial role in mediating the impacts of exercise. By regulating activity in neurons and preventing their hyperexcitability, astrocytes help maintain the balance that is required for optimal brain function, explained lead study author and graduate student Ki Yun Lee, of the University of Illinois Urbana-Champaign.
If we improve our understanding of how muscle contraction and growth is related to signaling in hippocampal neurons, we may be able to learn how to create exercise regimens that can be used to treat cognitive disorders such as dementia, added Lee.
Sources: Beckman Institute for Advanced Science and Technology, Neuroscience
