Glutamate in brain

Fig. 1.3 Reactions showing synthesis of glutamate in brain. Aspartate aminotransferase (1) glu-taminase (2) glutamate dehydrogenase (3) GABA aminotransferase (4) alanine aminotransferase (5) ornithine aminotransferase (6) Al-pyrroline 5-carboxylic acid dehydrogenase (7) and asparagine synthetase (8)...

This transfer of reducing equivalents is essential for maintaining the favorable NAD+/NADH ratio required for the oxidative metabolism of glucose and synthesis of glutamate in brain (McKenna et al., 2006). The malate-aspartate shuttle is considered the most important shuttle in brain. It is particularly important in neurons. It has low activity in astrocytes. This shuttle system is fully reversible and linked to amino acid metabolism with the energy charge and citric acid cycle of neuronal cells. 

Teichberg VI, Cohen-Kashi-Malina K, Cooper I et al (2009) Homeostasis of glutamate in brain fluids an accelerated brain-to-blood efflux of excess glutamate is produced by blood glutamate scavenging and offers protection from neuropathologies. Neuroscience 158 301-308... 

Inhibition of glutamate release was thought to be the mode of action of lamotrigine. It reduces MBS and kindling and also glutamate (and to a lesser extent GABA) release induced in brain slices by veratridine, which opens sodium channels. But it now seems likely that the actual block of sodium channels is its primary action (see later). 

Schoepp, D. D. Conn, P. J. (1993). Metabotropic glutamate receptors in brain function and pathology. Trends Pharmacol. Sci. 14, 13-20. 

Baslow MH (2000) Functions of W-acetyl-L-aspartatc and W-acetyl-L-asparty[glutamate in the vertebrate brain role in glial cell-specific signaling. J Neurochem 75 453—459... 

Glutamate transporters in brain are coded by five different but closely related genes, SLC1A1-4 and SLC1A6. There are several trivial names for each of the corresponding proteins. The transporters can all symport one Glu, with three Na+ and one H+, and antiport one K+ within each cycle, but they differ in their cellular expression. 

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