Abstract |
1. Two P2X(3)/P2X(2/3) receptor antagonists with different potencies were profiled electrophysiologically in a rat model of nerve injury. 2. A-317491 has poor CNS penetrance (blood:brain, 1:<0.05), and was therefore administered intravenously in chronic constriction injury (CCI)- and sham-operated rats to study the involvement of P2X(3) subunit-containing receptors in the periphery in neuropathic pain. A-317491 and Compound A were administered topically to the spinal cord to investigate the central contribution. 3. There were no significant inhibitory effects of A-317491 intravenous (i.v.) seen in sham-operated animals compared to vehicle controls. In CCI-operated animals, there were significant inhibitory effects of 3 mg kg(-1) A-317491 i.v. on C fibre-evoked responses, and with 10 mg kg(-1) A-317491 i.v. on A delta and C fibre-evoked responses. No significant effects of A-317491 were observed after topical application to the spinal cord. In contrast, when Compound A was administered spinally in CCI animals, there was a decrease in A delta and C fibre-evoked responses, and wind up. 4. These changes indicate that A-317491 has a selective effect on neuronal responses in CCI animals compared to sham, demonstrating an increased involvement of P2X(3)/P2X(2/3) receptors in sensory signalling following nerve injury. In addition, the more potent antagonist Compound A was effective spinally, unmasking a potential central role of P2X(3)/P2X(2/3) receptors at this site post nerve injury. These data support a role for P2X(3)/P2X(2/3) antagonists in the modulation of neuropathic pain.
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Authors | Caroline J Sharp, Alison J Reeve, Sue D Collins, Jo C Martindale, Scott G Summerfield, Becky S Sargent, Simon T Bate, Iain P Chessell |
Journal | British journal of pharmacology
(Br J Pharmacol)
Vol. 148
Issue 6
Pg. 845-52
(Jul 2006)
ISSN: 0007-1188 [Print] England |
PMID | 16770326
(Publication Type: Journal Article)
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Chemical References |
- A-317491
- P2rx2 protein, rat
- P2rx3 protein, rat
- Phenols
- Polycyclic Compounds
- Receptors, Purinergic P2
- Receptors, Purinergic P2X2
- Receptors, Purinergic P2X3
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Topics |
- Animals
- Constriction, Pathologic
- Evoked Potentials
(drug effects)
- Male
- Nerve Fibers, Unmyelinated
(drug effects, physiology)
- Neuralgia
(drug therapy, etiology, physiopathology)
- Phenols
(pharmacokinetics, pharmacology)
- Polycyclic Compounds
(pharmacokinetics, pharmacology)
- Rats
- Receptors, Purinergic P2
(physiology)
- Receptors, Purinergic P2X2
- Receptors, Purinergic P2X3
- Spinal Cord
(drug effects, physiology)
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