Excitatory amino acid receptors in piriform cortex do not show receptor desensitization.

We have investigated the proposed role of transmitter receptor desensitization as an explanation for the excitotoxicity rank order of several excitatory amino acid agonists as compared to kainic acid, using a brain slice of rat piriform cortex. Responses to glutamate, aspartate, quisqualate, n-methyl aspartate and kainate showed no evidence of receptor desensitization when studied with very long and large ionophoretic pulses, repeated ionophoretic pulses or by bath perfusion. At least in rat piriform cortex, the suggestion that kainate receptors do not desensitize while those to glutamate and quisqualate do, does not apply to nor explain the more potent kainate excitotoxicity.