Star-like cells may help the brain tune breathing rhythms

Scientists thought that star-shaped brain cells called astrocytes were steady, quiet supporters of their talkative, wire-like neighbors, called neurons. Now, an NIH study suggests that astrocytes may also have their say. It showed that silencing astrocytes in the brain’s breathing center caused rats to breathe at a lower rate and tire out on a treadmill earlier than normal. These were just two examples of changes in breathing caused by manipulating the way astrocytes communicate with neighboring cells.

A fresh look at the brain and breathing. Image credit: Jeffrey C. Smith lab, NIH/NINDS

“For decades we thought that breathing was exclusively controlled by neurons in the brain. Our results suggest that astrocytes actively help control the rhythm of breathing,” said Jeffrey C. Smith, Ph.D., senior investigator at the NIH’s National Institute of Neurological Disorders and Stroke (NINDS).

Dr. Smith’s lab investigates how breathing is controlled by the rhythmic firing of neurons in the preBötzinger complex, the brain’s breathing center that his lab helped discover. His team worked with Alexander Gourine, Ph.D., professor at University College London (UCL), whose lab found that astrocytes in neighboring parts of the brain may regulate breathing by sensing changes in blood carbon dioxide levels.

At least half of the brain is comprised of cells called glia and most of them are astrocytes. Recently scientists have shown that astrocytes may communicate like neurons by shooting off, or releasing, chemical messages, called transmitters, to neighboring cells.

The scientists tested the role of astrocytes in breathing by genetically modifying the ability of astrocytes in the preBötzinger complex to release transmitters.

When they hushed the astrocytes in rats by reducing transmitter release, the rats breathed and sighed at a lower rate than normal. In contrast, if they made the astrocytes chattier by increasing transmission, the rats breathed at higher resting rates and sighed more often.

Although the rats’ breathing rate increased when oxygen levels were lower or carbon dioxide levels higher, it was still lower than normal. Silencing astrocytes also decreased the rate at which the rats sighed under lower oxygen levels. Moreover, the rats became exhausted much earlier than normal. They could only run half the distance that normal rats could run on a treadmill before tiring out.

The primary goal of breathing is the exchange of carbon dioxide and oxygen that is critical for life. The results support the idea that astrocytes help the brain translate changes in these gases into breathing.

The team showed that these astrocytes used adenosine triphosphate (ATP) to communicate with other cells in the brain. Inactivating released ATP reduced resting breathing rates and the frequency of sighs under normal and low oxygen levels. (National Institutes of Health)

YOU MAY ALSO LIKE

Star Explosion Could Change Night Sky

There could be some dramatic changes to the night sky if astronomers are correct in their observations.

Too Much Salt? Unhealthy Blood Vessels Changes

Findings of a new study suggest adolescents who consume too much salt have measurable changes in their blood vessels associated with early signs of cardiovascular disease in adults.

Black Holes Hide in Our Cosmic Backyard

Monster black holes sometimes lurk behind gas and dust, hiding from the gaze of most telescopes. But they give themselves away when material they feed on emits high-energy X-rays that NASA's NuSTAR mission can detect.

VST Captures Three-In-One

Two of the sky’s more famous residents share the stage with a lesser-known neighbour in this enormous new three gigapixel image from ESO’s VLT Survey Telescope (VST).

The 2016 TB57 asteroid will come closest to Earth on Oct. 31

2016 TB57 is a small asteroid that will come closest to Earth on Oct. 31 at just beyond five times the distance of the moon.

Massive Lava Waves Detected on Solar System’s Most Volcanically Active Object

Io is the closest thing we have to hell in our Solar System, a Jovian moon that features hundreds of active volcanoes and expansive lakes filled with lava.