New studies show that astrocytes, also known as support cells or “silent cells,” have a larger impact on brain function than previously assumed.
Previously, astrocytes were thought to provide a supporting role to the brain by providing food and removing waste for neurons and serve as a protective barrier to keep harmful threats out of the brain. In 2016, senior author Marc Freeman, Ph.D., director of the OHSU Vollum Institute, and collaborators documented that astrocytes also transmit signals between neurons. Expanding on this discovery, researchers discovered how these cells transmit signals between one another. This is because astrocytes can turn on and off their ability to respond to chemical neurotransmitters in the brain, such as dopamine and glutamate. Researchers discovered that manipulating this ability can disrupt the behavior of fruit flies, indicating that these small changes can have a large impact on overall brain function.
This research discloses that astrocytes can directly respond to messages from all types of neurons and that these responses change with brain state, showing the larger and significant effects that astrocytes have on brain function. Some scientists fear that this discovery can overcomplicate the understanding of how the brain works, while researchers are finding more evidence to show how glial cells (the umbrella term of non-neuronal cells in which astrocytes fall into) can improve scientific understanding. Because of the complex nature of astrocytes, scientists believe that this discovery makes brain function understanding a lot more complicated than it was before. However, researchers believe that a positive effect of this discovery is that these cells could play a role in understanding brain injuries and neurodegenerative diseases, which could help to prevent diseases and improve treatments for conditions such as Alzheimer’s and Parkinson’s.
“We hope this begins to fundamentally change how the field thinks about astrocytes and their role in mediating neurophysiology and behavior,” said Freeman. “Over the long run, it should change how people think about developing therapies for regulation of attention, anxiety and mood.”
“Overall, these studies provide a different perspective on how astrocytes function and how information can move through the brain,” says cell biologist and neuroscientist Cagla Eroglu, a Howard Hughes Medical Institute Investigator at Duke University. “You need the astrocyte intermediary. It is not that the neurons do not sense [the chemical signals]. They do. But the brain is not wired that way. It’s wired in a way that there is an astrocyte intermediate.”
