Orphanin FQ is a functional anti-opioid peptide

J. S. Mogil, J. E. Grisel, R. K. Reinscheid, O. Civelli, J. K. Belknap, D. K. Grandy

357 Scopus citations


The heptadecapeptide orphanin FQ has recently been shown to be the endogenous agonist for the orphan opioid-like receptor, LC132. The molecular evidence that LC132 and orphanin FQ are evolutionarily related to other opioid receptors and their ligands suggests that these proteins may also play a role in modulating opiate actions. We now report that orphanin FQ (0.5-10 nmol), injected intracerebroventricularly in mice, does not produce hyperalgesia as suggested previously but rather reverses opioid-mediated (i.e. naloxone-sensitive) stress-induced antinociception in three different algesiometric assays. In addition to its antagonism of endogenous opioid antinociception, orphanin FQ dose-dependently (2.5-25 nmol) reverses systemic morphine antinociception (5 mg/kg, s.c.). Based on these data, we propose that orphanin FQ is a functional anti-opioid peptide.

Original languageEnglish (US)
Pages (from-to)333-337
Number of pages5
Issue number2
StatePublished - Oct 25 1996
Externally publishedYes

ASJC Scopus subject areas

  • Neuroscience(all)


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