Nociceptin attenuates opioid and gamma-aminobutyric acid(B) receptor-mediated analgesia in the mouse tail-flick assay.
Nociceptin (NC) and the opioid receptor like-1 receptors are widely distributed in areas of the neuraxis that are part of the descending modulatory pain system. We used the tail-flick assay in mice to assess the interaction between NC and other analgesic compounds acting on different areas of the descending pathway. Given by intracerebroventricular injection, NC induced hyperalgesia at 10 nmol (39% of reduction vs. control group). The same dose of NC reversed analgesia induced by distinct classes of analgesia-producing compounds such as morphine, dynorphin A or baclofen. NC caused a reduction of their antinociceptive effects: 61, 41 and 27%, respectively. Thus, NC at the supraspinal level appears to interact with both opioid and gamma-aminobutyric acid(B) systems producing anti-analgesic effects probably through the descending pathway for pain control.
Citterio
F
F
Schering-Plough Research Institute, San Raffaele Science Park, Via Olgettina, 58 20132, Milan, Italy.
Corradini
L
L
Smith
R D
RD
Bertorelli
R
R
D000701:Analgesics, Opioid / Q000494:pharmacology; D000818:Animals; D001418:Baclofen / Q000494:pharmacology; D004399:Dynorphins / Q000494:pharmacology; D018755:GABA Agonists / Q000494:pharmacology; D007276:Injections, Intraventricular; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009020:Morphine / Q000494:pharmacology; D009619:Nociceptors / Q000187:drug effects / Q000502:physiology; D018847:Opioid Peptides / Q000494:pharmacology*; D017288:Pain Threshold / Q000187:drug effects* / Q000502:physiology; D018080:Receptors, GABA-B / Q000502:physiology*; D011957:Receptors, Opioid / Q000819:agonists / Q000502:physiology*; D013116:Spinal Cord / Q000737:chemistry / Q000187:drug effects / Q000502:physiology; D013623:Tail; D000097629:Nociceptin
D000701:Analgesics, Opioid; D001418:Baclofen; D004399:Dynorphins; D018755:GABA Agonists; D009020:Morphine; D018847:Opioid Peptides; D018080:Receptors, GABA-B; D011957:Receptors, Opioid; D000097629:Nociceptin