How expensive is the astrocyte?

The energy cost of information processing is thought to be chiefly neuronal, with a minor fraction attributed to glial cells. However, there is compelling evidence that astrocytes capture synaptic K+ using their Na+/K+ ATPase, and not solely through Kir4.1 channels as was once thought. When this active buffering is taken into account, the cost of astrocytes rises by >200%. Gram-per-gram, astrocytes turn out to be as expensive as neurons. This conclusion is supported by 3D reconstruction of the neuropil showing similar mitochondrial densities in neurons and astrocytes, by cell-specific transcriptomics and proteomics, and by the rates of the tricarboxylic acid cycle. Possible consequences for reactive astrogliosis and brain disease are discussed.

Automated summary

Previously, it was believed that the energy cost of information processing was mainly attributed to neurons, with a minor fraction allocated to glial cells. However, there is compelling evidence that astrocytes also contribute significantly to this energy cost as they actively capture synaptic K+ using their Na+/K+ ATPase. This finding challenges the previous belief that astrocytes solely rely on Kir4.1 channels for K+ uptake. The implications of this discovery for reactive astrogliosis and brain diseases are discussed.