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

Research output: Contribution to journalArticlepeer-review

351 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

ASJC Scopus subject areas

  • Neuroscience(all)


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