Glutamate receptors NMDA receptor subunits

Kiyama H, Sato K, Kuba T, Tohyama M (1993) Sympathetic and parasympathetic ganglia express non-NMDA type glutamate receptors distinct receptor subunit composition in the principle and SIF cells. Mol Brain Res 79 345-348. 

V-methyl-D-aspartate receptors. Glutamate is the major excitatory neurotransmitter in the central nervous system (Ch. 15). Its receptors can be divided into three types AMPA/kainate, NMDA and metabotropic receptors. NMDA receptors are composed of two different types of subunit - NR1 and NR2. They play an important role in the induction of synaptic plasticity and excitotoxicity. 

Charpak S, Gahwiler BH, Do KQ, Knopfel T (1990) Potassiiun conductances in hippocampal neurons blocked by excitatory aminoacid transmitters. Natme 347 765-767 Chatterton JE, Awobuluyi M, Premkiunar LS, et al (2002) Excitatory glycine receptors containing the NR3 family of NMDA receptor subunits. Nature 415 793-798 Chen HX, Roper SN (2004) Tonic activity of metabotropic glutamate receptors is involved in developmental modification of short-term plasticity in the neocortex. J Neurophysiol 92 838-844... 

In addition to the multiplicity of receptor sites for glutamate, the NMDA receptors bear their own complexity as they are constructed as multimers from three distinguishable subunit classes (i.e. NR1, NR2 and NR3 subunit class). With regard to the stoichiometry of the NMDA receptor there is still some debate as to whether a native NMDA-gated ion channel within the cell membrane consists of either a tetramer or pentamer. More recently, it has been suggested that the tetramic stoichiometry is more probable (Laube et al., 1998 Hollmann, 1999). 

Laube, B., Hirai, H., Sturgess, M., Betz, H., Kuhse, J. Molecular determinants of agonist discrimination by NMDA receptor subunits Analysis of the glutamate binding site on the NR2B subunit. Neuron 1997, 18, 493-503. 

Cebers, G., Cebere, A., Kovacs, A.D., Hogberg, H., Moreira, T., Liljequist, S. (2001). Increased ambient glutamate concentration alters the expression of NMDA receptor subunits in cerebellar granule neurons. Neurochem. Int. 39 151-60. 

Bahn S, Wisden W (1997) A map of non-NMDA receptor subunit expression in the vertebrate brain derived from in situ hybridization histochemistry. In Monaghan DT, Wenthold RJ (Eds), The Ionotropic Glutamate Receptors. Totowa, NJ Humana Press Inc., pp 149-187. 

Non-NMDA ionotropic glutamate receptors (the majority sodium channel containing) can be subdivided into a-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) (comprising cloned subunits GluRl ) and kainate (GluR5-7, KAl-2) preferring receptors, with native receptors most likely to comprise either homo- or heteromeric pentamers of these subunits. 

While there are some reports of increased NMDA and non-NMDA receptor number in various cortical regions of schizophrenics including the prefrontal cortex, there are also indications of impaired glutamate innervation, such as reduction in its neuronal uptake sites (Ishimaru, Kurumaji and Torn 1994). Also it has been found that levels of the mRNA for the NRI subunit of the NMDA receptor in the hippocampus and its D-aspartate binding sites in the temporal cortex are both reduced more on the left than right side in schizophrenic brain. This is another indication of greater malfunction on the left side of the brain and the possibility that some schizophrenic symptoms arise from an imbalance between cross-cortical activity. 

NMDA receptor agonists are typically short-chain dicarboxylic amino acids such as glutamate, aspartate and NMDA. Acting at a site on the NR2 subunit, glutamate is the most potent endogenous agonist in the... 

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