Figure 1: Mechanisms of brain glucose metabolism.

Glucose is transported from blood vessels to astrocytes through endothelial cells. Astrocytes are specialized in glucose uptake. Glucose transporters (GLUTs) are present in the membrane of glial cells, as well as in neurons. As soon as glucose is transported into astrocytes via GLUT1, it is transformed into lactate through glycolysis. Lactate is then transported outside the astrocyte and taken up by neurons through monocarboxylate transporters. Intracellular lactate is oxidized to pyruvate through lactate dehydrogenase 1 (LDH1) and is metabolized along the oxygen pathway. Glucose may also be transported directly into neurons via GLUT3. Glucose then enters the glycolytic pathway and the tricarboxylic acid pathway for its later oxidation and the production of energy.

ADP = denosine diphosphate; ATP = adenosine triphosphate; GLUT = glucose transporter; LDH1 = lactate dehydrogenase 1; MCT = monocarboxylate transporter; NAD+ = oxidized nicotinamide adenine dinucleotide; NADH = reduced nicotinamide adenine dinucleotide.