ABSTRACT
In the brain, glutamine (Gln) participates in numerous metabolic processes that are common to all the mammalian tissues. This chapter discusses the roles of Gln in neurotransmission, a function specific to the nervous system, and to abnormalities of Gln metabolism critical for the pathogenesis of selected central nervous system diseases. It deals with the distribution of Gln in the brain tissues and subcellular fractions. The chapter describes in a natural history mode, the evidence that Gln serves as a precursor of the excitatory neurotransmitter glutamate (Glu) and the inhibitory neurotransmitter, gamma-aminobutyric acid (GABA). It focuses on the so-called glutamine/glutamate cycle (GGC), the mechanistic basis of the interplay between nerve cells and their supporting cells, astrocytes in generating neurotransmitter pools of Glu and GABA. The chapter summarizes the brain-specific aspects of glutamine transport, underscoring the distinct properties of glutamine carriers located in astrocytic and neuronal plasma membranes that couple Gln transport to GGC activity.
