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Titolo:
ELECTROPHYSIOLOGIC ANALYSIS OF PREEMPTIVE EFFECTS OF SPINAL OPIOIDS ON N-METHYL-D-ASPARTATE RECEPTOR-MEDIATED EVENTS
Autore:
CHAPMAN V; HALEY JE; DICKENSON AH;
Indirizzi:
UNIV COLL LONDON,DEPT PHARMACOL,GOWER ST LONDON WC1 E6BT ENGLAND
Titolo Testata:
Anesthesiology
fascicolo: 6, volume: 81, anno: 1994,
pagine: 1429 - 1435
SICI:
0003-3022(1994)81:6<1429:EAOPEO>2.0.ZU;2-M
Fonte:
ISI
Lingua:
ENG
Soggetto:
RAT DORSAL HORN; C-FIBER STIMULATION; FORMALIN TEST; INTRATHECAL MORPHINE; NOCICEPTIVE NEURONS; POSTOPERATIVE PAIN; NMDA RECEPTOR; SUBSTANCE-P; CORD; TRANSMISSION;
Keywords:
ANALGESICS, OPIOIDS; PAIN, PREEMPTIVE ANALGESIA; RECEPTORS, N-METHYL-D-ASPARTATE; SPINAL CORD;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
32
Recensione:
Indirizzi per estratti:
Citazione:
V. Chapman et al., "ELECTROPHYSIOLOGIC ANALYSIS OF PREEMPTIVE EFFECTS OF SPINAL OPIOIDS ON N-METHYL-D-ASPARTATE RECEPTOR-MEDIATED EVENTS", Anesthesiology, 81(6), 1994, pp. 1429-1435

Abstract

Background: Spinal N-methyl-D-aspartate (NMDA) receptor-mediated mechanisms may contribute to reduced opioid sensitivity in conditions of pain. The effectiveness of spinal opioids in inhibiting NMDA-mediated nociceptive events was assessed with two models. In addition, opioid dose-response curves with preemptive administration were compared with early and late postadministrations. Methods: Dorsal horn nociceptive neuronal responses were recorded in the intact halothane anesthetized rat to acute repetitive C-fiber electrical stimulation (0.1 and 0.5 Hz) and to the peripheral injection of 5% formalin. At 0.5 Hz but not at 0.1 Hz, there was an enhanced C-fiber evoked response of dorsal horn neurons elicited by repetitive C-fiber stimulation (wind-up), which is mediated by the NMDA receptor. Formalin produced a biphasic response; the late protracted inflammatory phase was NMDA receptor-mediated. Results: With 0.5-Hz stimulation a large degree of wind-up was elicited; it was less sensitive to 5 mu g morphine compared with the effect of the same dose on the residual wind-up elicited at 0.1 Hz. Preadministration and early postadministration of morphine were equieffective at inhibiting the second-phase formalin response. In contrast, administration of the fast-acting mu opioid, D-Ala-Gly-MePHe-Gly-ol, given late postadministration (during the second phase) was less effective than preadministration. Increasing the dose of D-Ala-Gly-MePHe-Gly-ol produced complete inhibitions. Conclusions: NMDA receptor-mediated neuronal responses, such as wind-up and the established second phase of the formalin response, are poorly responsive to opioids. Dose increases and preemptive opioids effectively inhibit these NMDA receptor-mediated events.

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Documento generato il 12/07/20 alle ore 06:27:27