Excitatory amino acids EAAs

Anatomical and pharmacological studies have both indicated that the two major transmitter systems within the brain are the inhibitory GABA ergic and the excitatory amino acid (EAA) pathways [264]. At least four different receptors mediate the action of EAA, they are named according to the most selective li-... 

As it is now clear that excitatory amino acids (EAA) play a critical role as neurotransmitters in the brain [279], in addition to the putative endogenous agonists, synthetic agonists such as NMDA 199 and (2J ,3S,4J )-a-(carboxycyclo-propyl)glycine 198 c have been identified, Eq. 79 [280]. 

Coderre, T. J. and Van Empel, I. The utility of excitatory amino acid (EAA) antagonists as analgesic agents. Comparison of the antinociceptive activity of various classes of EAA antagonists in mechanical, thermal and chemical nociceptive tests, Pain 1994, 59, 345-352. 

Excitatory Amino Acids (EAAs). Excitatory amino acids are claimed to be the principal excitatory transmitters in the reticular formation (34). EAAs including glutamate are involved in the positive feedback interaction between the cholinergic and the reticular neurons. 

In the recent past, the role of excitatory amino acids (EAAs) in the physiology and pathophysiology of the central nervous system has been widely investigated and elucidated (Meldrum and Garthwaite, 1990 McCullogh,... 

A third excitatory amino acid (EAA) receptor that is now receiving attention is the N-methyl-D-aspartate (NMDA) receptor. This receptor may be involved in epileptic discharges and hypoxia damage. There are also selective agonists (NMDA and cyclopentane glutamate) and a selective antagonist (D-APV5) available for sophisticated studies to demonstrate the extent brain processes are affected by NMDA activation of its receptors. 

The only reported antidote for domoic acid toxicity was described in a series of papers published shortly after the 1987 PEI disaster. These studies by Glavin, Pinsky and colleagues indicated that kynurenic acid, a broad-spectrum excitatory amino acid (EAA) antagonist which is actually present in the brain in small amounts, would reduce both behavioural toxicity and gastrointestinal lesions when administered 45 or 75 minutes after domoic acid in mice. Unfortunately very high doses were required (300 and 600 mg/ kg) and the time frame for the effect was fairly narrow. For these and other reasons kynurenic acid has little potential as a human medication. Nonetheless, the potential for developing such a drug still exists. 

Quisqualic Acid, eS)-ci-/fmino-3>5-dioio- ,2,4-oxadiazolidine-2-propanoic acid L -quisqualic acid 13 -(3.5 -dioxo- 1,2,4-oxodiazolidin-2-y])-L-alanine. C5H7N,05 mol wt 189.13. C 31.75%, H 3,73%, N 22.22%, O 42.30%, Excitatory amino acid (EAA) used to identify a specific subset... 

Most often more than one neurotransmitter is released at the same time. Aspartate and glutamate are excitatory amino-acids (EAAs) involved in pain transmission [4,5]. Glutamate is the main excitatory CNS nem-otransmitter and mediates rapid, short-duration depolarization of second-order neurons. Peptides such as substance P and neurokinin are responsible for delayed long-lasting depolarization. EAAs act on various receptors, which principally include alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic... 

There is substantial evidence fi om studies in the intact animal that these neurons are directly stimulated by hypoxia. Sun and colleagues have shown that microinjection of cyanide into the RVLM of rats evokes a pressor response (68). The RVLM reticulospinal sympathoexcitatory vasomotor neurons, many of which exhibit pacemaker-hke activity, are rapidly and reversibly excited in a dose-dependent manner when the cyanide is delivered by either microinjection or microiontophoresis (63,66,68,69). This excitation is not altered by blockade of ionotropic excitatory amino acid (EAA) receptors in this region (70). Fiuiher, during hypoxic excitation of these RVLM reticulospinal sympathoexcitatory vasomotor neurons, their response to baroreceptor stimulation is preserved, suggesting that the... 

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