運動は海馬ニューロンの発達を促進することで脳の健康を直接改善することができ、アストロサイトはその効果を仲介する重要な役割を果たします。 この研究は、アルツハイマー病などの認知障害に対する運動ベースの治療につながる可能性がある。
収縮する筋肉細胞からの化学信号を研究することは、運動によって脳の健康を改善する方法を示しています。
ベックマンの研究者は、収縮する筋肉からの化学信号がどのようにして脳の健康を促進するかを研究しました。 彼らの研究結果は、これらの信号が新しい脳ネットワークの成長と調節にどのように役立つかを明らかにすると同時に、運動を通じて脳の健康を改善する方法も示しています。
身体的および精神的な健康を改善する手段として、身体活動がよく引用されます。 ベックマン先端科学技術研究所の研究者らは、脳の健康をより直接的に改善する可能性があることを示しました。 彼らは、筋肉の運動によって放出される化学信号が脳内のニューロンの発達をどのように促進するかを研究しました。
彼らの研究は雑誌に掲載されました 神経科学。
重い重量を持ち上げる上腕二頭筋のように、運動中に筋肉が収縮すると、さまざまな化合物が血流に放出されます。 これらの化合物は、脳を含む体のさまざまな部分に移動する可能性があります。 研究者らは、運動が海馬と呼ばれる脳の特定の部分にどのような効果をもたらすかに特に興味を持っていた。
「海馬は学習と記憶、ひいては認知的健康にとって重要な領域です」と博士のキ・ユン・リー氏は言う。 イリノイ大学アーバナ・シャンペーン校の機械科学と工学の学生であり、この研究の筆頭著者。 したがって、運動が海馬にどのような利益をもたらすかを理解できれば、次のようなさまざまな症状に対する運動ベースの治療につながる可能性があります。[{” attribute=””>Alzheimer’s disease.
Hippocampal neurons (yellow) surrounded by astrocytes (green) in a cell culture from the study. Image provided by the authors. Credit: Image provided by the study authors: Taher Saif, Justin Rhodes, and Ki Yun Lee
To isolate the chemicals released by contracting muscles and test them on hippocampal neurons, the researchers collected small muscle cell samples from mice and grew them in cell culture dishes in the lab. When the muscle cells matured, they began to contract on their own, releasing their chemical signals into the cell culture.
The research team added the culture, which now contained the chemical signals from the mature muscle cells, to another culture containing hippocampal neurons and other support cells known as astrocytes. Using several measures, including immunofluorescent and calcium imaging to track cell growth and multi-electrode arrays to record neuronal electrical activity, they examined how exposure to these chemical signals affected the hippocampal cells.
The results were striking. Exposure to the chemical signals from contracting muscle cells caused hippocampal neurons to generate larger and more frequent electrical signals — a sign of robust growth and health. Within a few days, the neurons started firing these electrical signals more synchronously, suggesting that the neurons were forming a more mature network together and mimicking the organization of neurons in the brain.
However, the researchers still had questions about how these chemical signals led to growth and development of hippocampal neurons. To uncover more of the pathway linking exercise to better brain health, they next focused 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 said. Perhaps, then, they played a role in helping neurons respond to these signals.
The researchers found that removing astrocytes from the cell cultures caused the neurons to fire even more electrical signals, suggesting that without the astrocytes, the neurons continued to grow — perhaps to a point where they might become unmanageable.
“Astrocytes play a critical role in mediating the effects of exercise,” Lee said. “By regulating neuronal activity and preventing hyperexcitability of neurons, astrocytes contribute to the balance necessary for optimal brain function.”
Understanding 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 said.
Reference: “Astrocyte-mediated Transduction of Muscle Fiber Contractions Synchronizes Hippocampal Neuronal Network Development” by Ki Yun Lee, Justin S. Rhodes and M. Taher A. Saif, 2 February 2023, Neuroscience.
DOI: 10.1016/j.neuroscience.2023.01.028
In addition to Lee, the team also included Beckman faculty members Justin Rhodes, a professor of psychology; and Taher Saif, a professor of mechanical science and engineering and bioengineering.
Funding: NIH/National Institutes of Health, National Science Foundation