In crayfish and squid giant nerve fibers, glutamate appears to be an axon–glia signaling agent. We have investigated glutamate transport and metabolism by crayfish central nerve fibers in order to identify possible mechanisms by which glutamate could subserve this non-synaptic signaling function. Accumulation of radiolabeled l-glutamate by desheathed cephalothoracic nerve bundles was temperatur...

We have recently found that L-glutamate suppresses morphological changes of astrocytes induced by amyloid beta protein, adenosine 3',5'-cyclic monophosphate or phorbol ester in culture. To test the possibility that L-glutamate affects organization of the cytoskeleton, we investigated its effect on morphological changes induced by disruption of actin filaments with cytochalasin B. Cultured rat c...

Transport of acidic amino acids in Bacillus subtilis is an electrogenic process in which L-glutamate or L-aspartate is symported with at least two protons. This is shown by studies of transport in membrane vesicles in which a proton motive force is generated by oxidation of ascorbate-phenazine methosulfate or by artificial ion gradients. An inwards-directed sodium gradient had no (stimulatory) ...

The pharmacological properties of glutamate agonists were compared in astrocyte-rich and astrocyte-poor cultures derived from embryonic rat cerebral cortex. The object of this investigation was to determine the extent to which glutamate uptake might influence the receptor-mediated neurotoxic actions of these compounds. In astrocyte-rich cultures, using 30 min exposures, we observed that the pot...

N-acetyl glutamate synthase (NAGS) is the first enzyme in arginine biosynthetic pathway and catalyzes transfer of an acetyl group from acetyl-CoA to L-glutamate produce N-acetylglutamate (NAG). NAGS enzymes either consist two domains (classical NAGS) or a single domain (short S-NAGS). S-NAGS, although present many bacteria, have not been well characterized date. This study's focus kinetically c...

Tracer quantities (in 0.2 ml) of 13N-labeled glutamate, alanine, or glutamine(amide) were administered rapidly (less than or equal to 2 s) via the portal vein of anesthetized adult male rats. Liver content of tracer at 5 s was 57 +/- 6 (n = 6), 24 +/- 1 (n = 3), and 69 +/- 7 (n = 3)% of the injected dose, respectively. Portal-hepatic vein differences for the corresponding amino acids were 17 +/...

The role of glutamate receptors within the nucleus accumbens in morphine tolerance has been postulated. Previous studies have reported that glutamate receptors exert their effects in part through the release of nitric oxide (NO). In the present study, the effect of intra-accumbal injections of L-arginine, the NO precursor and L-NAME, the NOS inhibitor on the morphine tolerance in Wistar rats (2...

Regulation of extracellular glutamate levels by muscarinic receptors in the striatum of unanesthetized rats was investigated by microdialysis. Extracellular glutamate levels were elevated by intrastriatal perfusion of L-trans-pyrrolidine-2,4-dicarboxylic acid (L-trans-PDC), a competitive substrate of plasma membrane excitatory amino acid transporters. The nonselective muscarinic agonist, oxotre...

Recently, we have solved the crystal structure of L-glutamate oxidase (LGOX) from Streptomyces sp. X-119-6 (PDB code: 2E1M), the substrate specificity of which is strict toward L-glutamate. By a docking simulation using L-glutamate and structure of LGOX, we selected three residues, Arg305, His312, and Trp564 as candidates of the residues associating with recognition of L-glutamate. The activity...

The actions of L-glutamate and agonists, agents blocking their membrane receptors and dorsal root afferent volleys, were compared on intracellularly recorded neuronal activity in an in vitro horizontal slice preparation of the hamster spinal dorsal horn. Bath-applied L-glutamate or L-aspartate (less than or equal to 1 mM) rapidly depolarized and excited less than a third of the dorsal horn neur...