Naloxone blocks the analgesic action of levorphanol but not of dextrorphan in the leopard frog

Craig W. Stevens, Paul D. Pezalla

Research output: Contribution to journalArticle

32 Scopus citations

Abstract

Intraspinal injection of levorphanol (3 μg) at the lumbar area of the leopard frog, Rana pipiens, induced analgesia which was completely blocked by co-injection of naloxone (3 μg), whereas dextrorphan (3 μg) induced analgesia which was unaffected by naloxone. Subcutaneous levorphanol (20 or 80 mg/kg) induced a dose-dependent analgesia which was blocked by concurrent naloxone (2 mg/kg), while only the higher dose of dextrorphan (80 mg/kg) induced analgesia which was unaffected by concurrent naloxone at 8 or 80 mg/kg. These data are the first to indicate naloxone-insensitive, dextrorphan-induced analgesia.

Original languageEnglish
Pages (from-to)171-174
Number of pages4
JournalBrain Research
Volume301
Issue number1
DOIs
StatePublished - 28 May 1984

Keywords

  • amphibians
  • analgesia
  • dextrorphan
  • levorphanol
  • naloxone
  • μ-opiate receptor
  • σ-opiate receptor

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