Pharmacology of receptors for excitatory amino acids

Abstract

Abstract The pharmacological evidence for the existence of three distinct neuronal receptors for the excitatory amino acids is reviewed. Although most or all central neurones respond to the eponymous agonists N‐methyl‐D‐aspartate (NMDA), quisqualate, and kainate, and the blockade of their effects is reasonably consistent throughout the neuraxis, subtle regional variations are detected when other agonists are tested. Thus, the tryptophan metabolite quinolinate is completely NMDA‐mimetic in the hippocampus and neocortex but is almost inactive in the spinal cord. L‐Homocysteate resembles NMDA in the cord and striatum but is quisqualate‐like in the hippocampus. There is good evidence for the involvement of amino acids in the mediation of excitatory synaptic events; however, the regional differences in the actions of the endogenous agonists make positive identification of the chemical species active at a particular synaptic site, at best, rather tentative.