The intrathecal administration of excitatory amino acid receptor antagonists selectively attenuated carrageenan-induced behavioral hyperalgesia in rats.
A single unilateral injection of carrageenan (4.5-6.0 mg in 0.15-0.20 ml saline) into the rat hindpaw induced behavioral hyperalgesia as evidenced by a significant reduction in hindpaw withdrawal latency to a noxious thermal stimulus. The involvement of N-methyl-D-aspartate (NMDA) receptors in this model of hyperalgesia was examined by intrathecal administration of the selective excitatory amino acid (EAA) receptor antagonists: (+/-)-2-amino-5-phosphonopentanoic acid (AP-5), (+/-)-3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP), ketamine hydrochloride (ketamine), 7-chlorokynurenic acid (7-Cl kynurenic acid), and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX). The effects of dizocilpine maleate (MK-801) were studied under the same conditions and published previously (Ren et al., 1992) and the data are presented for comparison. While the withdrawal latencies of the non-injected paws and of the paws of naive rats were not significantly affected by application of the EAA receptor antagonists at doses tested, the paw withdrawal latencies of the carrageenan-injected paws were elevated dose dependently. The rank order of potency of these agents to reduce hyperalgesia was: MK-801 greater than or equal to AP-5 greater than or equal to CPP = 7-Cl kynurenic acid = ketamine much greater than CNQX greater than 0. In contrast, intrathecal injection of the opioid receptor agonists, [D-Ala2,MePhe4,Gly-ol5]enkephalin (DAMGO, mu-selective) and [D-Pen2,D-Pen5] enkephalin (DPDPE, delta-selective), produced antinociception in both injected and non-injected paws. DAMGO was much more potent, while DPDPE was less potent, than MK-801.(ABSTRACT TRUNCATED AT 250 WORDS)
Ren
K
K
Neurobiology and Anesthesiology Branch, National Institute of Dental Research, National Institutes of Health, Bethesda, MD 20892.
Williams
G M
GM
Hylden
J L
JL
Ruda
M A
MA
Dubner
R
R
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D000700:Analgesics / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D002351:Carrageenan / Q000633:toxicity; D016291:Dizocilpine Maleate / Q000494:pharmacology; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D020881:Enkephalin, D-Penicillamine (2,5)-; D004745:Enkephalins / Q000494:pharmacology; D006930:Hyperalgesia / Q000139:chemically induced / Q000188:drug therapy*; D007249:Inflammation / Q000503:physiopathology; D007278:Injections, Spinal; D007649:Ketamine / Q000494:pharmacology; D007736:Kynurenic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D008297:Male; D010879:Piperazines / Q000494:pharmacology; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors* / Q000502:physiology; D014633:Valine / Q000031:analogs & derivatives / Q000494:pharmacology
D000700:Analgesics; D004745:Enkephalins; D010879:Piperazines; D011810:Quinoxalines; D016194:Receptors, N-Methyl-D-Aspartate; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D007649:Ketamine; D016291:Dizocilpine Maleate; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; C056639:2-amino-5-phosphopentanoic acid; D020881:Enkephalin, D-Penicillamine (2,5)-; D002351:Carrageenan; C050592:3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid; D007736:Kynurenic Acid; D014633:Valine; C057013:7-chlorokynurenic acid