Inflammation enhances peripheral μ-opioid receptor-mediated analgesia, but not μ-opioid receptor transcription in dorsal root ganglia

Michael Schäfer, Yasuo Imai, George R. Uhl, Christoph Stein

Research output: Contribution to journalArticle

Abstract

μ-Opioid receptor agonist [d-Ala2,NMe-Phe4,Gly5-ol]enkephalin (DAMGO)-induced peripheral analgesic effects occur early in hindpaws inoculated with Freund's complete adjuvant and increase in parallel to the development of inflammatory signs. Antagonism of these effects by β-funaltrexamine, an irreversible μ-opioid receptor antagonist, suggests that the effective number of peripheral opioid receptors does not increase during early stages, but does so at later stages of the inflammation. As determined by a ribonuclease protection assay, μ-opioid receptor mRNA in dorsal root ganglia is abundant in untreated animals, but does not significantly increase following inflammation. Thus, peripheral analgesic efficacy of DAMGO is not correlated with transcription or number of μ-opioid receptors at early inflammatory stages. At later stages, however, the number of peripheral μ-opioid receptors appears to increase and may enhance opioid efficacy.

Original languageEnglish (US)
Pages (from-to)165-169
Number of pages5
JournalEuropean Journal of Pharmacology
Volume279
Issue number2-3
DOIs
StatePublished - Jun 12 1995

Keywords

  • Antinociception
  • Dorsal root ganglion
  • Primary afferent neuron
  • Ribonuclease protection assay
  • β-Funaltrexamine
  • μ-Opioid receptor

ASJC Scopus subject areas

  • Pharmacology
  • Cellular and Molecular Neuroscience

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