title: Intramuscular administration of morphine reduces mustard-oil-induced craniofacial-muscle pain behavior in lightly anesthetized rats.
abstract: 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 microl) 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 mu opioid receptor antagonist, but not naltrindole, a delta opioid receptor antagonist, nor norbinaltorphimine (nor-BNI), a kappa 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 mu opioid receptor. Our observations further support the clinical approach of administering opioids in the periphery for the treatment of craniofacial muscle nociception.
authors.affiliation: Department of Oral Physiology and BrainKorea 21, School of Dentistry, Kyungpook National University, 188-1, SamDeok 2ga, Chung-gu, Daegu 700-412, Republic of Korea.
authors.forename: Seung R
authors.initials: SR
authors.lastname: Han
authors.forename: Min K
authors.initials: MK
authors.lastname: Lee
authors.forename: Koang H
authors.initials: KH
authors.lastname: Lim
authors.forename: Gwi Y
authors.initials: GY
authors.lastname: Yang
authors.forename: Hye J
authors.initials: HJ
authors.lastname: Jeon
authors.forename: Jin S
authors.initials: JS
authors.lastname: Ju
authors.forename: Young W
authors.initials: YW
authors.lastname: Yoon
authors.forename: Sung K
authors.initials: SK
authors.lastname: Kim
authors.forename: Dong K
authors.initials: DK
authors.lastname: Ahn
mesh_terms: D000700:Analgesics / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D000768:Anesthesia, General; D000818:Animals; D007249:Inflammation / Q000139:chemically induced; D007267:Injections; D007273:Injections, Intramuscular; D008297:Male; D008406:Masseter Muscle / Q000187:drug effects / Q000503:physiopathology*; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D009149:Mustard Plant / Q000633:toxicity*; D009270:Naloxone / Q000494:pharmacology; D009271:Naltrexone / Q000031:analogs & derivatives / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology*; D009619:Nociceptors / Q000187:drug effects / Q000502:physiology; D010146:Pain / Q000139:chemically induced / Q000503:physiopathology / Q000517:prevention & control*; D010938:Plant Oils / Q000008:administration & dosage / Q000633:toxicity*; D011597:Psychomotor Performance / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D017465:Receptors, Opioid, delta / Q000037:antagonists & inhibitors; D017473:Receptors, Opioid, kappa / Q000037:antagonists & inhibitors; D017450:Receptors, Opioid, mu / Q000037:antagonists & inhibitors; D016037:Single-Blind Method; D013004:Somatostatin / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D000700:Analgesics; D009292:Narcotic Antagonists; D010938:Plant Oils; D017465:Receptors, Opioid, delta; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; C049352:phenylalanyl-cyclo(cysteinyltyrosyl-tryptophyl-ornithyl-threonyl-penicillamine)threoninamide; D009270:Naloxone; C051844:norbinaltorphimine; D013004:Somatostatin; D009271:Naltrexone; D009020:Morphine; C055382:naltrindole; C027793:mustard oil