NMDA and non-NMDA receptors mediating nociceptive and non-nociceptive transmission in spinal cord of cat.
The effects of excitatory amino acid (EAA) receptor agonists and blockers on the nociceptive and non-nociceptive transmission in cat spinal dorsal horn neurons were studied. About 80% of neurons were facilitated by iontophoretic injection of EAA receptor agonists (10-100 nA), such as N-methyl-D-aspartate (NMDA), quisqualic acid (QA), kainic acid (KA), and DL-homocysteic acid (DLH). The nociceptive responses, irregular spontaneous discharges, and C afferent induced-response of dorsal horn neuron, were reduced by the different EAA receptor blockers (35-150 nA), such as DL-2-amino-5-phosphono-valerate (APV), ketamine, 6,7-dinitro-quinoxaline-2, 3-dion (DNQX), and kynurenic acid (Kyn). Ketamine and Kyn had different effects on the long-lasting response and the short-lasting response of neurons induced by stimulation of A afferent fiber of the tibial nerve. The long-lasting response in 8/12 neurons was reduced by Kyn, but not by ketamine, and the short-lasting response was reduced by neither Kyn nor ketamine. The DLH-induced excitations were reduced by DNQX and, to a less extent, by APV. The results suggest that both NMDA and non-NMDA receptors are involved in spinal nociception; the non-nociceptive information is in part mediated by non-NMDA receptors.
Song
X J
XJ
Shanghai Brain Research Institute, Chinese Academy of Sciences.
Zhao
Z Q
ZQ
D000818:Animals; D002415:Cats; D004558:Electric Stimulation; D018691:Excitatory Amino Acid Antagonists; D005260:Female; D007608:Kainic Acid / Q000494:pharmacology; D008297:Male; D016202:N-Methylaspartate / Q000494:pharmacology*; D009412:Nerve Fibers / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D009619:Nociceptors / Q000502:physiology*; D016318:Quisqualic Acid / Q000494:pharmacology; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors*; D013116:Spinal Cord / Q000187:drug effects / Q000502:physiology*; D013979:Tibial Nerve / Q000502:physiology
D018691:Excitatory Amino Acid Antagonists; D016194:Receptors, N-Methyl-D-Aspartate; D016202:N-Methylaspartate; D016318:Quisqualic Acid; D007608:Kainic Acid