Evidence for separate involvement of different mu-opioid receptor subtypes in itch and analgesia induced by supraspinal action of opioids.

Abstract

The common adverse effect of centrally-injected mu-opioid receptor (mu-OR) agonists is pruritus. This study was conducted using mice to examine whether different subtypes of mu-OR would be responsible for pruritus and analgesia. Intracisternal injections of morphine and morphine-6beta-glucronide (M6G), but not M3G, produced an antinociceptive effect. Morphine, but neither M6G nor M3G, induced facial scratching, a pruritus-related response. Facial scratching following morphine was not affected by the mu(1)-OR antagonist naloxonazine at doses that inhibited the antinociceptive effects. The results suggest that different subtype and/or splice variants of mu-OR are separately involved in pruritus and antinociception of opioids.

• Authors: Tsugunobu Andoh, Yuichi Yageta, Mitsuhiro Konno, Tomomi Yamaguchi-Miyamoto, Hiroki Takahata, Hiroshi Nojima, Hideo Nemoto, Yasushi Kuraishi
• Journal: Journal of pharmacological sciences (J Pharmacol Sci) Vol. 106 Issue 4 Pg. 667-70 (Apr 2008) ISSN: 1347-8613 [Print] Japan
• PMID: 18403901 (Publication Type: Journal Article)

Chemical References

• Analgesics, Opioid
• Morphine Derivatives
• Narcotic Antagonists
• Oprm protein, mouse
• Receptors, Opioid, mu
• Naloxone
• morphine-6-glucuronide
• Morphine
• naloxonazine
• morphine-3-glucuronide

Topics

• Analgesics, Opioid (administration & dosage, toxicity)
• Animals
• Behavior, Animal (drug effects)
• Dose-Response Relationship, Drug
• Injections, Subcutaneous
• Male
• Mice
• Mice, Inbred ICR
• Morphine (administration & dosage, toxicity)
• Morphine Derivatives (administration & dosage)
• Naloxone (administration & dosage, analogs & derivatives)
• Narcotic Antagonists (administration & dosage)
• Pain Measurement
• Pain Threshold (drug effects)
• Pruritus (chemically induced, metabolism, prevention & control)
• Receptors, Opioid, mu (agonists, metabolism)
• Time Factors