The μ-opioid receptor is necessary for [D-Pen2,D-Pen5]enkephalin-induced analgesia

Ichiro Sora, Masahiko Funada, George R. Uhl

Research output: Contribution to journalArticlepeer-review


Interactions between δ-opioid receptors and morphine-preferring CL-opioid receptor subtypes have been suggested. Availability of transgenic μ-opioid receptor knockout mice allows assessment of μ-opioid receptor roles in the analgesia produced by the classical δ-opioid receptor agonist [D-Pen2,D-Pen5]enkephalin (DPDPE) in hot-plate and tail-flick tests. DPDPE analgesia was dramatically reduced in μ-opioid receptor knockout mice in a gene-dose-dependent fashion. The analgesia induced by this classic δ-opioid receptor agonist depends on intact μ-opioid receptors, suggesting that selective δ-opioid receptor drugs may require μ-opioid receptor occupancies for full efficacy.

Original languageEnglish (US)
JournalEuropean Journal of Pharmacology
Issue number2-3
StatePublished - Apr 1997


  • δ-Opioid receptor
  • μ-Opioid receptor knockout mouse
  • DPDPE ([D-Pen,D-Pen]enkephalin

ASJC Scopus subject areas

  • Cellular and Molecular Neuroscience
  • Pharmacology


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