Inhibition of strychnine-allodynia is mediated by spinal adenosine A1- but not A2-receptors in the rat.
Intrathecal (i.t.) strychnine produces localized allodynia in the rat without peripheral or central nerve injury. Intrathecal CPA (A1-selective agonist) and CGS-21680 (A2-selective agonist) dose-dependently inhibited strychnine-allodynia but with a 50-fold difference in potency (0.02-0.07 vs. 2.7-3.1 microgram, respectively). The anti-allodynic effect of CPA and CGS was completely blocked by pretreatment with the A1-selective antagonist, DPCPX (10 microgram i.t. ), but unaffected by the A2-selective antagonist, CSC (2 microgram i.t. ). The results indicate that spinal A1-, but not A2-, receptors modulate abnormal somatosensory input in the strychnine model, and suggest a difference in spinal purinergic modulation in injury vs. non-injury models of allodynia.
Khandwala
H
H
School of Pharmacy, Memorial University of Newfoundland, St. John's, Newfoundland, Canada.
Zhang
Z
Z
Loomis
C W
CW
D000241:Adenosine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002110:Caffeine / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects; D007278:Injections, Spinal; D008297:Male; D010146:Pain / Q000139:chemically induced / Q000503:physiopathology* / Q000517:prevention & control*; D010627:Phenethylamines / Q000008:administration & dosage / Q000494:pharmacology*; D058906:Purinergic P1 Receptor Agonists; D058915:Purinergic P1 Receptor Antagonists; D051381:Rats; D017207:Rats, Sprague-Dawley; D018047:Receptors, Purinergic P1 / Q000502:physiology*; D013116:Spinal Cord / Q000187:drug effects / Q000502:physiology* / Q000503:physiopathology; D013331:Strychnine; D014970:Xanthines / Q000008:administration & dosage / Q000494:pharmacology
D010627:Phenethylamines; D058906:Purinergic P1 Receptor Agonists; D058915:Purinergic P1 Receptor Antagonists; D018047:Receptors, Purinergic P1; D014970:Xanthines; C061282:2-(4-(2-carboxyethyl)phenethylamino)-5'-N-ethylcarboxamidoadenosine; C081320:8-(3-chlorostyryl)caffeine; D002110:Caffeine; C051360:1,3-dipropyl-8-cyclopentylxanthine; D013331:Strychnine; D000241:Adenosine