Comparison of the spinal anti-nociceptive effects of ES-242-1 and MK-801, two different NMDA antagonists, in rats.
The purpose of this study was to determine whether ES-242-1, a novel N-methyl-D-aspartate (NMDA) receptor antagonist of microbial origin, has anti-nociception at the spinal level and to evaluate how its anti-nociceptive effect differs from that of MK-801, a non-competitive NMDA receptor antagonist. Agents were injected intrathecally (0.1, 1.0 and 10 microg) through a previously implanted PE tube in rats. Formalin (2%, 100 microl) was injected subcutaneously into the left hindpaw 15 min after each antagonist administration. Licking time as a nociceptive behavior was measured in three stages after formalin-injection, such as early phase (0-9 min), late first phase (10-29 min) and late second phase (30-60 min). In the early phase, the largest dose of ES-242-1 significantly decreased total licking time, although MK-801 did not show any significant reduction. With the treatment of 1.0 and 10 microg MK-801, total licking time in both late first and second phases was significantly suppressed, although the smallest dose (0.1 microg) of ES-242-1 showed a significant reduction in the late second phase. These results indicate that ES-242-1 is highly effective against tonic pain, such as inflammatory pain.
Hamada
F
F
Department of Otorhinolaryngology, Tokyo Medical University, 6-7-1 Nishi-Shinjuku, Shinjuku, Tokyo 160-0023, Japan. fhamada@mbg.sphere.ne.jp
Noutsuka
H
H
Hamada
Y
Y
Goto
H
H
D000818:Animals; D016291:Dizocilpine Maleate / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology*; D007278:Injections, Spinal; D008297:Male; D009619:Nociceptors / Q000187:drug effects* / Q000378:metabolism; D010146:Pain / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D010147:Pain Measurement / Q000187:drug effects; D017288:Pain Threshold / Q000187:drug effects / Q000502:physiology; D011714:Pyrans / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013116:Spinal Cord / Q000187:drug effects* / Q000378:metabolism; D013997:Time Factors
D018691:Excitatory Amino Acid Antagonists; D011714:Pyrans; D016194:Receptors, N-Methyl-D-Aspartate; C073561:ES 242-1; D016291:Dizocilpine Maleate