title: Nonopioid placebo analgesia is mediated by CB1 cannabinoid receptors.
abstract: Placebo analgesia is mediated by both opioid and nonopioid mechanisms, but so far nothing is known about the nonopioid component. Here we show that the specific CB1 cannabinoid receptor antagonist 5-(4-chlorophenyl)-1-(2,4-dichloro-phenyl)-4-methyl-N-(piperidin-1-yl)-1H-pyrazole-3-carboxamide (rimonabant or SR141716) blocks nonopioid placebo analgesic responses but has no effect on opioid placebo responses. These findings suggest that the endocannabinoid system has a pivotal role in placebo analgesia in some circumstances when the opioid system is not involved.
authors.affiliation: Department of Neuroscience, University of Turin Medical School and National Institute of Neuroscience (INN), Turin, Italy. fabrizio.benedetti@unito.it
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Benedetti
authors.forename: Martina
authors.initials: M
authors.lastname: Amanzio
authors.forename: Rosalba
authors.initials: R
authors.lastname: Rosato
authors.forename: Catherine
authors.initials: C
authors.lastname: Blanchard
mesh_terms: D018712:Analgesics, Non-Narcotic / Q000378:metabolism*; D002853:Chromatography, Liquid; D006801:Humans; D013058:Mass Spectrometry; D015394:Molecular Structure; D017288:Pain Threshold / Q000502:physiology; D010880:Piperidines / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology*; D015990:Placebo Effect; D011720:Pyrazoles / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology*; D043884:Receptor, Cannabinoid, CB1 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000077285:Rimonabant
chemical_list: D018712:Analgesics, Non-Narcotic; D010880:Piperidines; D011720:Pyrazoles; D043884:Receptor, Cannabinoid, CB1; D000077285:Rimonabant