A-Amino-3-hydroxy-5-methyl-4-isoxazole propionate

AMPAR. (a-Amino-3-hydroxy-5-methyl-4-isoxazole propionic acid) receptor a non-NMDA-type ionotropic transmembrane receptor for glutamate that mediates fast synaptic transmission in the central nervous system. 

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. 

Fletcher, E. J. and Lodge, D. New developments in the molecular pharmacology of a-amino-3-hydroxy-5-methyl-4-isoxazole propionate and kainate receptors. Pharmacol. Ther. 70 65-89,1996. 

In vitro studies on excitotoxicity suggest that while both NMDA and a-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)/kainate (KA) receptors can mediate excitotoxicity (see Ch. 15), these classes of glutamate receptors do not do so equally. Experiments with cortical or hippocampal cell cultures suggest that much of the neuronal death associated with brief, intense glutamate exposure is mediated by NMDA receptor activation, probably because this can induce lethal amounts of Ca2+ influx more rapidly than can AMPA/KA receptor stimulation. 

AMPA a-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid CCK cholecystokinin... 

Ionotropic glutamate receptors mediate fast excitatory neurotransmission in practically all areas of the central nervous system (CNS). They are also critical for both the induction and expression of synaptic plasticity, and have been implicated in diverse pathological conditions, such as epilepsy, ischemic brain damage, anxiety, and addiction. There are three subtypes of ionotropic glutamate receptors that are named after their high-affinity agonists as a-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA), N-1nethyl-D-aspartate (NMDA), and kainate (KA) receptors (1). 

Lesions of the basal forebrain cholinergic system using a-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) result in impaired attentional, but not mnemonic, function in rats (Muir et al., 1995) and monkeys (Voytko et al., 1994), an effect which has been confirmed using more selective IgG-saporin lesions (Baxter et al., 1995 Everitt 8c Robbins, 1997). 

Sharp JW, Ross CM, Koehnle TJ, Gietzen DW. 2004. Phosphorylation of Ca /calmodulin dependent protein kinase type II and the a-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptor in response to a threonine-devoid diet. Neuroscience 126 1053-1062. 

The receptors for Glu and the other EAAs are categorized into major two groups ionotropic, and metabotropic (Fig. 15.4). The three ionotropic receptor types are ciassified based on their seiective affinity for the EAA ligands N-methyl-D-aspartate (NMDA), a-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA), and kainite... 

The water and lipid soluble vitamin E analogue, trolox, protected cultured foetal murine cortical neurones against damage induced by exposure to either iron ions (50 xM Fe and 50 xM Fe ) or ultraviolet light of primary wave length (> 60 %) 253.7 run, consistent with an ability to inhibit free radical-mediated cytotoxicity (Chow etal. 1994). Trolox also reduced neuronal death induced by 24 h exposure to a-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (10 (xM), but not that induced by N-methyl-D-aspartate (15 jxM). When combined with the N-methyl-o-aspartate receptor antagonist dextrorphan (100 jxM), trolox also reduced the neuronal injury induced by glucose deprivation. 

Pinealocytes can express different subunits of all major classes of glutamate receptors, i.e. the ionotropic receptors for M-methyl-L-aspartate, a-amino-3-hydroxy-5-methyl-4-isoxazole propionate, and kainate type (Wisden and Seeburg 1993, Sato et al. 1993, TOlle et al. 1993, Petralia et al. 1994), as well as the metabotropic receptors (Petralia et al. 1996). 

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