Monocarboxylate transporters MCT4 and MCT2 to be used as an energy substrate by neurons. Pyruvate also generates lactate (lac), which is shuttled via Glucose is converted by glycolysis into pyruvate (pyr), which is oxidized toД¬O 2 by the mitochondrial Krebs cycle, producing NADH and then ATP. Energy: The main energy substrate of the brain is glucose (glc), which crosses the endothelium and entersДЄstrocytes via the glucose transporter GLUT1. Astrocytes form metabolic domains and are coupled by gap junctions, through which they exchange Neurons and oligodendrocytes (blue) are not ( Inset) Astrocytes (green) reside between blood vessels (red) and neurons (yellow). These metabolic processes in astrocytes and neurons are the basis for brain mapping using functional magnetic resonance imagingДЄnd positron emission tomography (PET)-methods that capture local metabolism either directly or indirectly via hemodynamicД¬hanges ( Magistretti 2008 Belanger et al. Astrocytes consume considerable energy for their own needs and the cycling of metabolically relevant substances for neurons. With a smaller investment in action potentials and neurotransmitter recycling ( Harris et al. Much of the ATP produced in the brain is spent by neurons on the recovery of ion gradients challenged by postsynaptic potentials, The synapse, the site of highest energy demand ( Harris et al. One set of astrocytic processes ensheaths the vasculature and a second set reaches toward Hydrophilic energy substrates are translocated across membranes via specific transporter proteins ( Fig. Although oxygen diffuses freely into the parenchyma, glucose and other 2013) to ensure adequate delivery of oxygen and glucose. The microvasculature consists of a complex and dense network of highly interconnected blood vessels ( Weber et al.

A special microarchitecture has evolved to support this extreme need, in which glial cells play a central role ( Fig. Glucose of the total body turnover ( Magistretti 2008). Although theД«rain accounts for merely 2% of body weight, it receives в€ј15% of cardiac output, and uses 20% of the oxygen and 25% of the

The energy requirements of the central nervous system (CNS) are very high compared with those of other organs.

Outstanding questions in this field are the role of oligodendrocytes, the metabolic behavior of the different subtypes ofДЄstrocytes during development and disease, and the emerging notion that metabolism may participate directly in information Substrates and precursors for biosynthesis, and recycling neurotransmitters, oxidized scavengers, and other waste products. Although neurons spend most of the brainвЂ™s energy on signaling, astrocytesД«ear the brunt of the metabolic load, controlling the composition of the interstitial fluid, supplying neurons with energy Brain metabolism is characterized by fuel monodependence, high-energy expenditure, autonomy from the rest of body, local recycling,ДЄnd marked division of labor between cell types.

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