Responses of spinal dorsal horn neurones evoked by myelinated primary afferent stimulation are blocked by excitatory amino acid antagonists acting at kainate/quisqualate receptors.
The effects of excitatory amino acid antagonists on responses, evoked by myelinated primary afferent stimulation, in neurones of the spinal cord dorsal horn has been investigated in an isolated hemisected spinal cord preparation from the neonatal rat. The first evoked action potential of most responses was reversibly blocked by either 5 mM kynurenic acid (80%) or 10 microM CNQX (91%). The small latency variability and the ability of some of these responses to follow repetitive stimulation suggested that they were evoked monosynaptically. The selective NMDA receptor antagonist, CPP, blocked some later components of responses consisting of bursts of action potentials but not the first evoked action potential. The results support the suggestion that myelinated primary afferents release excitatory amino acids which act at kainate/quisqualate receptors.
Morris
R
R
Department of Veterinary Preclinical Sciences, University of Liverpool, U.K.
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D000200:Action Potentials / Q000187:drug effects; D000596:Amino Acids / Q000037:antagonists & inhibitors*; D000818:Animals; D000831:Animals, Newborn; D000870:Anterior Horn Cells / Q000502:physiology*; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000187:drug effects; D007736:Kynurenic Acid / Q000494:pharmacology; D009186:Myelin Sheath / Q000502:physiology; D009475:Neurons, Afferent / Q000502:physiology*; D010879:Piperazines / Q000494:pharmacology; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D018091:Receptors, AMPA; D018092:Kainic Acid Receptors; D017981:Receptors, Neurotransmitter / Q000378:metabolism*; D013116:Spinal Cord / Q000166:cytology* / Q000502:physiology
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D000596:Amino Acids; D007736:Kynurenic Acid; D010879:Piperazines; D011810:Quinoxalines; D018091:Receptors, AMPA; D018092:Kainic Acid Receptors; D017981:Receptors, Neurotransmitter; C050592:3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid