Researchers have shown that muscles release chemical signals that stimulate neuronal development in the brain.
- Researchers have studied muscle cells and neurons to understand how physical activity affects the brain.
- They discovered that muscles released chemicals into the bloodstream that boosted the development and activity of neurons in the hippocampus.
- Furthermore, glial cells, called astrocytes, are essential for regulating the activity of neurons. Their absence could cause problems.
We’ve known for years that physical activity is good for brain health. But why exactly? This is the question posed by researchers at the Beckman Institute for Advanced Science and Technology (USA).
Their work found an explanation: the chemical signals released by muscles during exercise promote neuronal development. The results were presented in the scientific journal Neuroscience in April 2023.
Muscles release chemical signals that boost neurons
When muscles – like the biceps – contract during a workout, they release different chemicals into the bloodstream. The researchers wanted to understand their effects on the hippocampus, a brain area linked to learning and memory. To achieve this, they took muscle cells from mice and put them in culture. When they were able to contract by releasing their chemical signals, the team placed them in contact with neurons in the hippocampus and other supporting cells, called astrocytes.
“Exposure to chemical signals from contracting muscle cells caused neurons in the hippocampus to generate larger and more frequent electrical signals, a sign of robust growth and health. Within days, neurons had began to emit these electrical signals in a more synchronized fashion, suggesting that they together formed a more mature network and mimicked the organization of neurons in the brain.”explain the authors in a press release from their establishment.
Astrocytes: these glial cells regulate neuronal development
After this first discovery, the researchers then focused on the role of astrocytes in this link between exercise and brain development. They eliminated these star-shaped glial cells from their cultures. The neurons then emitted even more electrical signals. This suggests that without the astrocytes they continued to grow, “perhaps to a point where they could become unmanageable”say the scientists.
“Astrocytes play an essential role in mediating the effects of exercise”explained the main author, Ki Yun Lee. “By regulating neuronal activity and preventing hyperexcitability of neurons, astrocytes contribute to the balance necessary for optimal brain function”concluded the expert.
For him, understanding the chemical pathway between muscle contraction and hippocampal neuron growth and regulation is just the first step in determining how exercise improves brain health. The study could also “contribute to the development of more effective exercise programs for cognitive disorders such as Alzheimer’s disease”according to the specialist.