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Longman Dictionary of Contemporary English
The Collaborative International Dictionary
Douglas Harper's Etymology Dictionary
glutamate

1876, from glutamic acid (see gluten) + -ate (3).

Wiktionary
glutamate

n. (context chemistry English) Any salt or ester of glutamic acid.

WordNet
glutamate

n. a salt or ester of glutamic acid

Wikipedia
Glutamate (neurotransmitter)

Glutamate is an amino acid, one of the twenty amino acids used to construct proteins, and as a consequence is found in high concentration in every part of the body. In the nervous system it plays a special additional role as a neurotransmitter: a chemical that nerve cells use to send signals to other cells. In fact glutamate is by a wide margin the most abundant neurotransmitter in the vertebrate nervous system. It is used by every major excitatory information-transmitting pathway in the vertebrate brain, accounting in total for well over 90% of the synaptic connections in the human brain.

Chemical receptors for glutamate fall into three major classes, known as AMPA receptors, NMDA receptors, and metabotropic glutamate receptors. Many synapses use multiple types of glutamate receptors. AMPA receptors are ionotropic receptors specialized for fast excitation: in many synapses they produce excitatory electrical responses in their targets a fraction of a millisecond after being stimulated. NMDA receptors are also ionotropic, but they differ from AMPA receptors in being permeable, when activated, to calcium. Their properties make them particularly important for learning and memory. Metabotropic receptors act through second messenger systems to create slow, sustained effects on their targets. A fourth class, known as kainate receptors, are similar in many respects to AMPA receptors, but much less abundant.

Because of its role in synaptic plasticity, glutamate is involved in cognitive functions such as learning and memory in the brain. The form of plasticity known as long-term potentiation takes place at glutamatergic synapses in the hippocampus, neocortex, and other parts of the brain.

Glutamate works not only as a point-to-point transmitter, but also through spill-over synaptic crosstalk between synapses in which summation of glutamate released from a neighboring synapse creates extrasynaptic signaling/ volume transmission. In addition, glutamate plays important roles in the regulation of growth cones and synaptogenesis during brain development as originally described by Mark Mattson.

Usage examples of "glutamate".

Monica is allergic to monosodium glutamate, the taste-improver professional cooks use so that they can serve appetizing leftovers.

It was soon apparent that the vital molecule was the transmitter amino acid, glutamate, well known as one of the commonest of the excitatory neurotransmitters of the brain and present in high concentration within neurons.

Like all transmitters, glutamate is released from a presynaptic terminal when the nerve axon running to that terminal fires.

Annette Dolphin, working with Tim Bliss, showed that, when the perforant pathway is stimulated in vivo, there is an increased release of glutamate in the hippocampus, and the biochemical mechanisms of this release were mapped in some detail by Marina Lynch.

The glutamate is released from the presynaptic side of the synapse between the incoming perforant nerve and the hippocampal neuron.

On this basis, Lynch and Bliss were to argue, rather as Kandel had done earlier for serotonin in Aplysia, that it was presynaptic plasticity that was important for the initiation of LTP, and the postsynaptic cell was simply doing what it had to as a result of the increase in the strength of the glutamate signal it was receiving.

Thus although each receptor type responds to glutamate, some will respond to chemically similar molecules as well, others show different forms of specificity.

One class of glutamate receptor is known as the NMDA receptor, because the effects of glutamate can be mimicked by injection of the chemically similar substance N-methyl-D-aspartic acid.

Drugs which interact with the other types of glutamate receptor are without effect.

More NMDA sites would mean a postsynaptic cell more responsive to glutamate and hence more likely to fire.

Burchuladze, R and Rose, S P R Memory formation in day-old chicks requires NMDA but not non-NMDA glutamate receptors, in press, 1992.

What with our stopping for barely edible fast-food chicken-absolutely rife with monosodium glutamate, sodium nitrate, and God knows what other poisons-we arrived at the Sea and Sand Motel on the southern outskirts of Oceanside.

All readings looked fine: glutamate, serotonin, do-pamine, cortical suppressant, amygdala regulator, P15, BDNF to strengthen the synaptic connections for learning in the hippocampus.

Maus abhorred tea bags, pressure cookers, canned fruit cocktail, bottled mayonnaise, instant coffee, iceberg lettuce, monosodium glutamate, eggs poached in geometric shapes, New England boiled dinners, and anything resembling a smorgasbord, salad bar, or all-you-can-eat buffet.

Worcestershire sauce, hydrolyzed vegetable protein, monosodium glutamate, nonfat dry milk, dehydrated onions, flavoring, sugar, caramel color, spice, cysteine and thiamine hydrochloride, gum arabic.