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 have underlined the fundamental importance of astrocytic metabolism for neuronal function with a particular emphasis on the fact that, without continuous support from the astrocytic partners in synaptic function, glutamatergic and GABAergic neurotransmission would not be possible. It is thought provoking that these neurotransmission processes, which account for the vast majority of synaptic activity in the brain, have been made totally dependent on astrocytic metabolic support, particularly with regard to replenishment of the respective neurotransmitters.
About the Author
Arne Schousboe obtained a Ph. D. in biochemistry from the University of Copenhagen in 1968 and, after a short period as Assistant Professor at the University of Copenhagen, he completed a post-doc period ( January 1972-September 1973) with Dr. Eugene Roberts at the Department of Neuroscience, City of Hope National Medical Center in Los Angeles.
Anne B. Walls, Ph.D., is a postdoc researcher at the University of Copenhagen. She obtained her M.Sc. in Pharmacy from the Danish University of Pharmaceutical Sciences, Copenhagen, Denmark, in 2006 and her Ph.D. from the Norwegian University of Science and Technology (NTNU), Trondheim, Norway, in 2010.
Lasse K. Bak, Ph.D., is an associate professor at the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen. His main field of research is the coupling between brain cell signaling events mediated by cAMP and calcium, and the functional and metabolic responses they elicit. He has published more than 50 scientific peer-reviewed papers, reviews, and book chapters.
Helle S. Waagepetersen is Full Professor of Cellular Neuropharmacology at the Department of Drug Design and Pharmacology, University of Copenhagen. She has served as Handling Editor of the Journal of Neurochemistry and is a member of several editorial boards.
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