Glutamate, nitric oxide and cell-cell signalling in the nervous system

Since the finding by [Johnson and Ascher (1987)][1] demonstrating that glycine enhances electrophysiological responses mediated by N-methyl-d-aspartate (NMDA)b-sensitive glutamatergic receptors, considerable interest has been devoted to this topic (for reviews, see [Dingledine et al. , 1990][2]; [

Glycine and N-Methyl-d-Aspartate Receptors: Physiological Significance and Possible Therapeutic Applications

New concepts on the mechanism of action of benzodiazepines.

Ibotenate, a rigid structural analogue of glutamate, markedly enhances the hydrolysis of membrane inositol phospholipids, as reflected by the stimulation of [3H]inositol monophosphate formation in rat hippocampal slices prelabeled with [3H]inositol and treated with Li+. Quisqualate, homocysteate, L-glutamate, and L-aspartate also induce a significant (albeit weaker) increase in [3H]inositol monophosphate formation, whereas N-methyl-D-aspartate, kainate, quinolinate, and N-acetylaspartylglutamate are inactive. The increase in [3H]inositol monophosphate formation elicited by the above-mentioned excitatory amino acids is potently and selectively antagonized by DL-2-amino-4-phosphonobutyric acid, a dicarboxylic amino acid receptor antagonist. These results suggest that, in the hippocampus, a class of dicarboxylic amino acid recognition sites is coupled with phospholipase C, the enzyme that catalyzes the hydrolysis of membrane inositol phospholipids.

A. Guidotti

Papers

The regulation of cyclic guanosine monophosphate in rat cerebellum: possible involvement of putative amino acid neurotransmitters