Breath of Fresh Air for Astrocytes

 

In the brain, supporting cells called astrocytes may actually play a fundamental role in regulating unconscious breathing. These star-shaped cells can sense the carbon dioxide concentration levels in their proximity and stimulate the surrounding neurons to regulate respiration. This additional role of astrocytes may help understand a few respiratory illnesses, such as cot death.

Astrocytes, a form of glial cells, may help neurons process information as well. During times of exercise, the acidity level of the blood increases due to the excess presence of CO2. The conventional ideology is that the pH change was sensed specialized neurons that serve to tell the lungs to exhale. According to the study, astrocytes can sense even a small decrease in pH which is caused by an increase in calcium ions (Ca2+) and the release of an ATP. This ATP then goes to the astrocytes which then trigger the surrounding neurons to cause the lungs to exhale to remove the excess CO2 from the blood.

The research team did so by placing a calcium-sensitive fluorescent protein (Case12) and promoter sequence that ensured the expression of the gene exclusively in astrocytes into the brains of living rats. When they shined light on the brain, Case12 lit up with a brightness scale that was similar to that of calcium. When the calcium increased, the pH level decreased clearly establishing the property of astrocytes to sense pH levels.

Link: http://www.nature.com/news/2010/100715/full/news.2010.355.html