Astroglia and Brain Metabolism: Focus on Energy and Neurotransmitter Amino Acid Homeostasis

Abstract

Abstract The present outline of astrocytic metabolic pathways involved in glucose and amino acid metabolism provides detailed information about the enzymatic pathways involved, as well as a description of the basic properties of the enzymes including regulatory mechanisms. Hence, the glycolytic pathway and glycogen metabolism are outlined, followed by a detailed account of pyruvate oxidation and its role as a substrate for the tricarboxylic acid (TCA) cycle. Moreover, a detailed description of the main enzymes involved in glutamate metabolism is provided and the role of the glutamate-glutamine cycle is explained. Since this text is primarily covering astrocytic metabolism, an emphasis has been placed on a discussion of the significance of the astrocyte specific enzymes pyruvate carboxylase and glutamine synthetase, which enable these cells to perform a net synthesis of glutamine, the precursor for synthesis of glutamate and γ-aminobutyrate (GABA), the main neurotransmitters of the brain. With this, we hav...