title: Differential interactions of cholecystokinin and FLFQPQRF-NH2 with mu and delta opioid antinociception in the rat spinal cord.
abstract: An in vivo preparation of the rat spinal cord was used to investigate the electrophysiological actions of two non-opioid peptides, cholecystokinin (CCK8) and FLFQPQRF-NH2 (FMRFamide-like peptide) applied intrathecally. These compounds were examined alone and as a pretreatment before DAGO, a mu opioid agonist, and DSTBULET, a delta opioid agonist, both which selectively reduce C-fibre evoked dorsal horn neurone activity elicited by transcutaneous electrical stimulation. Given alone, CCK8 (1 microgram) elicited a modest enhancement of C-fibre induced activity which returned to control levels after 20 min, while FLFQPQRF-NH2 (10 micrograms) had no significant effect on C-fibre evoked firing. As a pretreatment, however, both peptides selectively prevented the inhibition of C-fibre evoked activity normally resulting from intrathecal DAGO, while having no effect on that resulting from DSTBULET. Further, CCK8 enhanced the facilitation of C-fibre evoked firing normally observed with low doses of DAGO. These data indicate that the anti-opioid roles suggested for CCK8 and FLFQPQRF-NH2 may be specific for neural elements utilizing the mu opioid receptor.
authors.affiliation: Department of Pharmacology, University College, London.
authors.forename: D S
authors.initials: DS
authors.lastname: Magnuson
authors.forename: A F
authors.initials: AF
authors.lastname: Sullivan
authors.forename: G
authors.initials: G
authors.lastname: Simonnet
authors.forename: B P
authors.initials: BP
authors.lastname: Roques
authors.forename: A H
authors.initials: AH
authors.lastname: Dickenson
mesh_terms: D000818:Animals; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D004745:Enkephalins / Q000008:administration & dosage / Q000494:pharmacology*; D005071:Evoked Potentials / Q000187:drug effects; D007278:Injections, Spinal; D008297:Male; D009412:Nerve Fibers / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D009842:Oligopeptides / Q000008:administration & dosage / Q000494:pharmacology*; D010146:Pain / Q000503:physiopathology*; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000187:drug effects / Q000502:physiology*; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu; D012844:Sincalide / Q000494:pharmacology*; D013116:Spinal Cord / Q000187:drug effects / Q000502:physiology* / Q000503:physiopathology
chemical_list: D004745:Enkephalins; D009842:Oligopeptides; D011957:Receptors, Opioid; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; C054868:tyrosyl-seryl(O-tert-butyl)-glycyl-phenylalanyl-leucyl-threonine; C053651:phenylalanyl-leucyl-phenylalanyl-glutaminyl-prolyl-glutaminyl-arginyl-phenylalaninamide; D012844:Sincalide