glutamate
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Glutamate is a central junction for interchange of amino nitrogen, glutamate facilitates both amino acid synthesis and degradation.
In the liver, glutamate is the terminus for release of ammonia from amino acids, and the intrahepatic concentration of glutamate modulates the rate of ammonia detoxification into urea.
In pancreatic beta-cells, oxidation of glutamate mediates amino acid-stimulated insulin secretion.
In the central nervous system, glutamate serves as an excitatory neurotransmittor.
- L-glutamate is the major excitatory neurotransmitter in the brain and is responsible for normal brain function. High glutamate exposure triggers neuronal death, a process known as excitotoxicity. Excitotoxicity is associated with acute and chronic neurodegenerative diseases.
- Excessive glutamate signaling can lead to excitotoxicity, a phenomenon whereby over-activation of glutamate receptors initiates neuronal death. Glutamate can be toxic to white-matter oligodendrocytes.
Glutamate is also the precursor of the inhibitory neurotransmittor GABA, as well as glutamine, a potential mediator of hyperammonemic neurotoxicity.
Pathology (Disorders of glutamate metabolism)
mutations of the glutamate dehydrogenase in a form of congenital hyperinsulinism associated with asymptomatic hyperammonemia
disruptions of glutamate metabolism
- pyridoxine-dependent seizures
missense mutation in the gene encoding one of the two mitochondrial glutamate/H(+) symporters in autosomal recessive neonatal myoclonic epilepsy (#15592994#)
See also
glutamate oxidation
glutamate receptors
glutamate excitotoxicity
glutamate synapse
References
Nicholls DG. Mitochondrial dysfunction and glutamate excitotoxicity studied in primary neuronal cultures. Curr Mol Med. 2004 Mar;4(2):149-77. PMID: #15032711#
Aarts MM, Tymianski M. Molecular mechanisms underlying specificity of excitotoxic signaling in neurons. Curr Mol Med. 2004 Mar;4(2):137-47. PMID: #15032710#
Tanaka K. Antibiotics rescue neurons from glutamate attack. Trends Mol Med. 2005 Jun;11(6):259-62. PMID: #15949765#
Kelly A, Li C, Gao Z, Stanley CA, Matschinsky FM. Glutaminolysis and insulin secretion: from bedside to bench and back. Diabetes. 2002 Dec;51 Suppl 3:S421-6. PMID: #12475785#
Nedergaard M, Takano T, Hansen AJ. Beyond the role of glutamate as a neurotransmitter. Nat Rev Neurosci. 2002 Sep;3(9):748-55. PMID: #12209123#
Kelly A, Stanley CA. Disorders of glutamate metabolism. Ment Retard Dev Disabil Res Rev. 2001;7(4):287-95. PMID: #11754524#