Gap junctions can connect the cytosolic compartments of adjacent astroglia. They allow intercellular flux of low-molecular weight (< ~ 1 kDa) compounds, including metabolites and second messengers. Only recently, however, has it been proposed that gap junctions may serve an additional role in the astrocytic metabolic network which maintains synaptic transmission. The brain seems to be using a strategy analogous to power-grid systems used in modern societies to supply energy; the astrocytic 'power-grid' can deliver the metabolic energy to neurons as needed. Such an astroglial energy grid is malleable and can change the size and shape in response to metabolic activity of neuronal network to deliver energy from the root source of energy of the brain, the blood glucose, to neurons.