Abstract |
Glutamate receptor response properties of nociceptive synapses on neurokinin 1 receptor positive (NK1R+) lamina I neurons were determined 3 days after induction of chronic peripheral inflammation with Freund's Complete Adjuvant (CFA). A significant increase in the AMPAR/NMDAR ratio was found during inflammation, which was associated with a significant reduction in the quantal amplitude of NMDAR-mediated synaptic currents. A significant shortening of the quantal AMPA current decay, a greater inward rectification of the AMPAR-mediated eEPSC amplitude and an increased sensitivity to the Ca2+-permeable AMPAR channel blocker 1-naphthylacetyl spermine ( NAS) was also observed, indicating an increase in the contribution of Ca2+-permeable AMPARs at this synapse during inflammation. Furthermore the reduced effectiveness of the NR2B-specific antagonist CP-101,606 on NMDAR-mediated eEPSCs together with a decrease in Mg2+ sensitivity suggests a down regulation of the highly Mg2+-sensitive and high conductance NR2B subunit at this synapse. These changes in glutamatergic receptor function during inflammation support the selective effectiveness of Ca2+-permeable AMPAR antagonists in inflammatory pain models and may underlie the reported ineffectiveness of NR2B antagonists in spinal antinociception.
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Authors | Kristina S Vikman, Beth K Rycroft, Macdonald J Christie |
Journal | The Journal of physiology
(J Physiol)
Vol. 586
Issue 2
Pg. 515-27
(Jan 15 2008)
ISSN: 0022-3751 [Print] England |
PMID | 18033811
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- NR2B NMDA receptor
- Receptors, AMPA
- Receptors, N-Methyl-D-Aspartate
- Receptors, Neurokinin-1
- Receptors, Opioid
- Freund's Adjuvant
- Calcium
- Nociceptin Receptor
- Oprl protein, rat
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Topics |
- Animals
- Calcium
(metabolism)
- Excitatory Postsynaptic Potentials
(physiology)
- Female
- Freund's Adjuvant
- Inflammation
(chemically induced, complications, metabolism)
- Male
- Neural Conduction
(physiology)
- Pain
(etiology, metabolism)
- Posterior Horn Cells
(metabolism)
- Rats
- Rats, Sprague-Dawley
- Receptors, AMPA
(metabolism)
- Receptors, N-Methyl-D-Aspartate
(metabolism)
- Receptors, Neurokinin-1
(metabolism)
- Receptors, Opioid
(metabolism)
- Synapses
(metabolism)
- Nociceptin Receptor
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