Table 1 Glucose metabolism

Glucose transport: Blood glucose is transferred across the blood–brain barrier through glucose transporter 1 (GLUT1) expressed in endothelial cells and astrocytes [10]. Then, glucose is transported into neurons through GLUT3 and GLUT4 [11,12,13,14], or imported into oligodendrocytes and microglia through GLUT1 [15, 16]

Glycolysis: Glucose undergoes glycolysis in the cytoplasm through a process consisting of 10 enzymatic reactions without oxygen involvement. The first five reaction steps are in the ATP investment phase, in which two molecules of ATP are used to metabolize one molecule of glucose. The remaining five reaction steps are the ATP payoff phase, through which two molecules of pyruvates and four molecules of ATP are generated. In net, two molecules of ATP are generated during each glycolysis cycle. Additionally, two molecules of NADH are generated from glycolysis and can be transported into mitochondria through the malate-aspartate shuttle for OXPHO

TCA cycle and OXPHO: Pyruvate derived from glycolysis is transported into mitochondria and undergoes oxidation through reactions in the TCA cycle. NADH and FADH₂ are the product of the TCA cycle and serve to transfer electrons to feed the electron transport chain that drives ATP synthesis. About 30 molecules of ATP are generated in net from OXPHO per pyruvate.]