In the brain, to each one neurone, there are 9 astrocytes (1). They are surrounded by capillaries and are close to the both blood-brain and blood-cerebrospinal “the first cellular barrier encountered by glucose entering the brain tissue, which makes them a prevalent site of glucose uptake”(2)

Astrocytes interacts with neurons and synapses; they express neurotransmitter receptors and transporters. The delivery of lactate from astrocytes to neurons is enhanced during increased synaptic activity. But astrocytes (according to 2) are also able to process fatty acids for the ketogenesis depending on neuronal energy demands. The ketone bodies and acetoacetate can replace glucose as the major source of brain energy during starvation and in the immature brain. Ketone bodies produced by astrocytes seem to be used together with lactate as substrates for neuronal oxidative metabolism in situations such as enhanced synaptic activity and hypoxia . (more…)