Neuron-glia interactions: Astrocytes in the air.

摘要

In recent years it has become increasingly apparent that astrocytes have roles beyond supporting neurons. Now, Gourine et al. add to these cells' repertoire by showing that astrocytes in the brainstem contribute to respiratory control. Because astrocytes provide a link between neurons and the vasculature, the authors investigated the possibility that they integrate levels of CO_2 and pH in the blood and the brain parenchyma, and relay this information to chemosensitive neurons in brainstem areas that control breathing. They measured the reactivity of astrocytes near the ventral surface of the medulla (VSM) to changes in pH by monitoring intracellular Ca~(2+) concentrations. Experiments in rat brainstem slices showed that a 0.2 unit decrease in pH induced an immediate increase in Ca~(2+) levels in VSM astrocytes. Astrocytes located adjacent to the VSM vasculature were particularly sensitive to changes in pH. The cellular Ca~(2+) response to acidification is propagated across astrocytic networks through the release of adenosine triphosphate (ATP). In brainstem slices, a 0.2 unit pH decrease triggered ATP release in the VSM, and this effect was prevented by blocking ATP signalling.