The effects of morphine on carrageenin-induced spinal c-Fos expression are completely blocked by beta-funaltrexamine, a selective mu-opioid receptor antagonist.
We have demonstrated that pre-administered morphine (3 mg/kg, i.v.) decreased spinal c-Fos expression induced 2 h after intraplantar carrageenin (55 +/- 5% reduction, P < 0.0001). These effects were completely blocked by pre-administered beta-funaltrexamine (10 mg/kg, i.v., 24 h prior to stimulation) a selective long-lasting mu-opioid receptor antagonist. In conclusion, these results clearly demonstrate that the effects of morphine on noxiously-evoked spinal c-Fos expression are essentially mediated via mu-opioid receptors.
Physiopharmacologie du Système Nerveux, INSERM U.161, Paris, France.
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Honoré
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Buritova
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Besson
D000818:Animals; D002351:Carrageenan / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009271:Naltrexone / Q000031:analogs & derivatives* / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology*; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017450:Receptors, Opioid, mu / Q000037:antagonists & inhibitors / Q000502:physiology*; D013116:Spinal Cord / Q000166:cytology / Q000187:drug effects / Q000502:physiology*
D009292:Narcotic Antagonists; D016760:Proto-Oncogene Proteins c-fos; D017450:Receptors, Opioid, mu; D009271:Naltrexone; C024524:beta-funaltrexamine; D009020:Morphine; D002351:Carrageenan