Involvement of endogenous orphanin FQ in electroacupuncture-induced analgesia.
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.
Tian
J H
JH
Neuroscience Research Center, Beijing Medical University, PR China.
Xu
W
W
Zhang
W
W
Fang
Y
Y
Grisel
J E
JE
Mogil
J S
JS
Grandy
D K
DK
Han
J S
JS
D000698:Analgesia; D000818:Animals; D015671:Electroacupuncture; D005260:Female; D018847:Opioid Peptides / Q000378:metabolism* / Q000494:pharmacology*; D010146:Pain / Q000503:physiopathology*; D051381:Rats; D017208:Rats, Wistar; D000097629:Nociceptin
D018847:Opioid Peptides; D000097629:Nociceptin