NMDA receptor antagonists attenuate mechanical hyperalgesia in rats with unilateral inflammation of the hindpaw.
The effects of N-methyl-D-aspartate (NMDA) receptor antagonists on mechanical hyperalgesia associated with tissue inflammation were studied. Following an injection of the inflammatory agent, complete Freund's adjuvant, into the rat hindpaw, there was a significant decrease in threshold and an increase in response duration to mechanical stimuli, suggesting that a state of mechanical hyperalgesia was induced. The intrathecal administration of the NMDA receptor antagonists, dizocilpine maleate and (+/-)-2-amino-5-phosphonopentanoic acid, significantly increased mechanical threshold and reduced response duration in the inflamed hindpaw, but had no effect on the non-injected paw. The results suggest that NMDA receptor activation may contribute to the mechanical hyperalgesia that follows peripheral tissue inflammation.
Ren
K
K
Neurobiology and Anesthesiology Branch, National Institute of Dental Research, National Institutes of Health, Bethesda, MD 20892.
Dubner
R
R
D015763:2-Amino-5-phosphonovalerate / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D016291:Dizocilpine Maleate / Q000008:administration & dosage / Q000494:pharmacology; D005620:Freund's Adjuvant; D007249:Inflammation / Q000139:chemically induced / Q000503:physiopathology*; D007278:Injections, Spinal; D008297:Male; D008465:Mechanoreceptors / Q000187:drug effects; D010147:Pain Measurement / Q000187:drug effects*; D017288:Pain Threshold / Q000187:drug effects; D010812:Physical Stimulation; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors*
D016194:Receptors, N-Methyl-D-Aspartate; D016291:Dizocilpine Maleate; D015763:2-Amino-5-phosphonovalerate; D005620:Freund's Adjuvant