J Korean Neurol Assoc.  1995 Sep;13(3):438-452.

Antinociceptive Actions of Excitatory Amino Acid Recetor Antagonists in the Spinal Cord of a Rat Model for Neuropathic Pain

• Lee SA
• Leem JW
• Park ES
• Choi EJ
• Nam TS
• Paik KS

Abstract

It has been proposed that excitatory amirio acid (EAA) receptors mediate sensitimtion of central neurons that may play a cruc ial role in the generation of neuropathic pain. We performed experiments using a rat model of peripheral neuropathy to provide direct evidence that EAA receptors are involved in mediating hyperexcitability of dorsal hom neurons in the spinal cord. The results obtained were as follows: 1)Rats that received an unilateral ligation of L5 and L6 spinal nerves showed behaviorally increased mechanical sensitivity of the hindpaw m the side of nerve 2)Wide dynamic range (VVDR) spinal dorsal hom neurons on the side of the ligation showed enhanced brush-and pinch-evoked responses. 3)WDR neurons on the side of the ligation were classified into three groups, based on responses to iontophoretically applied EAA receptor ligands: neurons responsive preferentially to NMDA (15 of 40, 37.5%), neurons responsive preferentially to ANPA (20 of 40, 50%), non-NMDA receptor agonist, and neurons responsive well to both NMDA and AMPA (5 of 40, 12.5%). 4)AMPA responsive neurons were suppressed by GAMS, non-NMDA receptor antagonist, only in their brush-evoked response, whereas NMDA responsive neurons were suppressed by AP-5, NMDA receptor antagonist, only in their pinch-evoked response. The results suggest that following a peripheral nerve injury, spinal WDR neurons are enhanced in their mechanical responsiveness where increased response to innocuous mechanical stimulus is mediated by non-NMDA receptor while that to noxious one is by NMDA receptor.

MeSH Terms

alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid
Animals
Excitatory Amino Acids*
Ligands
Ligation
Models, Animal*
N-Methylaspartate
Negotiating
Neuralgia*
Neurons
Peripheral Nerve Injuries
Peripheral Nervous System Diseases
Rats*
Spinal Cord*
Spinal Nerves
Excitatory Amino Acids
Ligands
N-Methylaspartate
alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid