Role of Ca2+-permeable non-NMDA glutamate receptors in spinal nociceptive transmission

The functional role of Ca(2+)-permeable non-NMDA receptors in spinal nociceptive processing was investigated using joro spider toxin (JSTx), a selective blocker of these receptors, JSTx 0.25 and mu g administered spinally produced a significant facilitation of the C-fibre evoked response and post-discharge, but not the A-fibre response, of dorsal horn neurones recorded in adult rats. This may result from a block of Ca(2+)-permeable AMPA receptors located on GABAergic interneurones. At higher doses, this facilitation of responses was lost, suggesting additional Ca(2+)-permeable non-NMDA receptors, possibly kainate receptors, in excitatory spinal pathways. Thus, functional Ca(2+)-permeable AMPA receptors are present within the dorsal horn, predominantly within inhibitory pathways, and play a role distinct from other excitatory amino acid receptors in spinal nociceptive processing. NeuroReport 11:3199-3202 (C) 2000 Lippincott Williams & Wilkins.