FIGURE 2.

Energy metabolism in the brain. The uptake and utilization of glucose by cells in the brain requires the neurovascular unit, which is composed of brain capillary endothelial cells, pericytes, astrocytes, oligodendrocytes, microglia, and neurons. Glucose enters cells through specific glucose transporters (GLUTs), such as GLUT1, GLUT2, and GLUT7 in astrocytes, GLUT1 in oligodendrocytes, and GLUT3 and GLUT4 in neurons. Numerous metabolic intermediates formed by glucose in the brain can also be oxidized to produce energy, such as lactate, pyruvate, and glutamate. The dynamic regulatory mechanism of lactic acid metabolism between astrocytes and neurons is known as the astrocyte–neuron lactate shuttle. Neurons release glutamate to stimulate glucose uptake by astrocytes. Astrocytes produce lactic acid by aerobic glycolysis in the cytoplasm and then transport to neurons.