Intramuscular administration of morphine reduces mustard oil-induced craniofacial muscle pain behavior in lightly anesthetized rats

Seung R. Han, Min K. Lee, Koang H. Lim, Gwi Y. Yang, Hye J. Jeon, Jin S. Ju, Young W. Yoon, Sung K. Kim, Dong K. Ahn

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


The present study investigated the role of peripheral opioid receptors in mustard oil-induced nociceptive behavior and inflammation in the masseter muscles of lightly anesthetized rats. Experiments were carried out on male Sprague-Dawley rats weighing between 300 and 400 g. After initial anesthesia with sodium pentobarbital (40 mg/kg, i.p.), one femoral vein was cannulated and connected to an infusion pump for the intravenous infusion of sodium pentobarbital. The rate of infusion was adjusted to provide a constant level of anesthesia. Mustard oil (MO, 30 μl) was injected into the mid-region of the left masseter muscle via a 30-gauge needle. Intramuscularly-administered morphine significantly reduced shaking behavior but not MO-induced inflammation. Intramuscular pretreatment with naloxone, an opioid receptor antagonist, reversed antinociception produced by intramuscularly-administered morphine, while intracisternal administration of naloxone did not affect the antinociception of peripheral morphine. Pretreatment with d-Pen-Cys-Tyr-d-Trp-Orn-Thr-Pen-Thr-NH2 (CTOP), a μ opioid receptor antagonist, but not naltrindole, a δ opioid receptor antagonist, nor norbinaltorphimine (nor-BNI), a κ opioid receptor antagonist, reversed intramuscularly-administered morphine-induced antinociception. These results indicate that intramuscularly-administered morphine produces antinociception in craniofacial muscle nociception and that this intramuscularly-administered morphine-induced antinociception is mediated by a peripheral μ opioid receptor. Our observations further support the clinical approach of administering opioids in the periphery for the treatment of craniofacial muscle nociception.

Original languageEnglish
Pages (from-to)361-370
Number of pages10
JournalEuropean Journal of Pain
Issue number3
Publication statusPublished - 2008 Apr

Bibliographical note

Funding Information:
The authors thank Professor Ro for technical assistance of assessment of muscle pain. This work was supported by a Grant (R01-2006-000-10488-0) from the Basic Research Program of the Korea Science & Engineering Foundation.

Copyright 2008 Elsevier B.V., All rights reserved.


  • Antinociception
  • Morphine
  • Muscle pain
  • Nociceptive behavior
  • Peripheral opioid receptors

ASJC Scopus subject areas

  • Anesthesiology and Pain Medicine


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