Role of Ca2+-permeable non-NMDA glutamate receptors in spinal nociceptive transmission.
The functional role of Ca2+-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 1 microg 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 Ca2+-permeable AMPA receptors located on GABAergic interneurones. At higher doses, this facilitation of responses was lost, suggesting additional Ca2+-permeable non-NMDA receptors, possibly kainate receptors, in excitatory spinal pathways. Thus, functional Ca2+-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.
Stanfa
L C
LC
Department of Pharmacology, University College London, UK.
Hampton
D W
DW
Dickenson
A H
AH
D000818:Animals; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D018698:Glutamic Acid / Q000378:metabolism; D008297:Male; D009412:Nerve Fibers / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D009619:Nociceptors / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010146:Pain / Q000473:pathology / Q000503:physiopathology*; D020671:Posterior Horn Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000187:drug effects / Q000378:metabolism*; D013111:Spider Venoms / Q000494:pharmacology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*
D015220:Calcium Channels; C044936:JSTX spider toxin; D018091:Receptors, AMPA; D013111:Spider Venoms; D018698:Glutamic Acid