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

The functional role of Ca2+-permeable non-NMDA receptors in spinal nocicept ive processing was investigated using joro spider toxin (JSTx), a selective blocker of these receptors, JSTx 0.25 and mu g administered spinally produ ced a significant facilitation of the C-fibre evoked response and post-disc harge, but not the A-fibre response, of dorsal horn neurones recorded in ad ult rats. This may result from a block of Ca2+-permeable AMPA receptors loc ated on GABAergic interneurones. At higher doses, this facilitation of resp onses was lost, suggesting additional Ca2+-permeable non-NMDA receptors, po ssibly kainate receptors, in excitatory spinal pathways. Thus, functional C a2+-permeable AMPA receptors are present within the dorsal horn, predominan tly within inhibitory pathways, and play a role distinct from other excitat ory amino acid receptors in spinal nociceptive processing. NeuroReport 11:3 199-3202 (C) 2000 Lippincott Williams & Wilkins.