Reticulospinal neurones activate excitatory amino acid receptors

Paired intracellular recordings were used to study the monosynaptic excitatory postsynaptic potentials (EPSP) in lamprey motoneurones evoked by stimulation of single reticulospinal Müller and Mauthner cells. The chemical component of the synaptic potentials was depressed by both application of the non-selective excitatory amino acid antagonists kynurenic acid and cis-2,3-piperidine dicarboxylate. The N-methyl-D-aspartate (NMDA) antagonists Mg2+ and 2-amino-5-phosphonovalerate caused a selective depression of a late component of the EPSP. Thus, fast-conducting reticulospinal neurones appear to release an excitatory amino acid acting at both NMDA and non-NMDA receptors.