We have studied the in vivo signaling mechanisms involved in nociceptin/orphanin FQ (Noci)-induced pain responses by using a flexor- reflex paradigm. Noci was 10,000 times more potent than substance P (SP) in eliciting flexor responses after intraplantar injection into the hind limb of mice, but the action of Noci seems to be mediated by SP. Mice pretreated with an NK1 tachykinin receptor antagonist or capsaicin, or mice with a targeted disruption of the tachykinin 1 gene no longer respond to Noci. The action of Noci appears to be mediated by the Noci receptor, a pertussis toxin-sensitive G protein-coupled receptor that stimulates inositol trisphosphate receptor and Ca2+ influx. These findings suggest that Noci indirectly stimulates nerve endings of nociceptive primary afferent neurons through a local SP release.
|Original language||English (US)|
|Number of pages||5|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|State||Published - Sep 1 1998|
ASJC Scopus subject areas