Involvement of endogenous orphanin FQ in electroacupuncture-induced analgesia

Neuroreport. 1997 Jan 20;8(2):497-500. doi: 10.1097/00001756-199701200-00024.


Recent studies suggest that the novel opioid peptide orphanin FQ (OFQ) is involved in pain modulation. We found that intracerebroventricular (i.c.v.) administration of OFQ in the rat produced a dose-dependent antagonism of the analgesia induced by 100 Hz electroacupuncture (EA) stimulation as measured in the radiant heat tail-flick assay. Antisense oligonucleotides injected i.c.v. potentiated EA analgesia, presumably by interfering with the expression of the OFQ receptor in brain. These results suggest that endogenous OFQ exerts a tonic antagonistic effect on EA-induced analgesia. No such antagonism was observed when OFQ was injected intrathecally (i.t.). Rather, it appears that spinal OFQ produced a marked analgesic effect and enhanced EA-induced analgesia. These findings are consistent with the experimental results obtained in rats where morphine-induced analgesia is antagonized by i.c.v. OFQ and potentiated by i.t. OFQ.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Analgesia
  • Animals
  • Electroacupuncture*
  • Female
  • Opioid Peptides / metabolism*
  • Opioid Peptides / pharmacology*
  • Pain / physiopathology*
  • Rats
  • Rats, Wistar


  • Opioid Peptides
  • nociceptin