title: Decreased motivational properties of morphine in mouse models of cancerous- or inflammatory-chronic pain: implication of supraspinal neuropeptide FF(2) receptors.
abstract: Our main purpose was to evaluate the influence of cancer pain on the rewarding properties of morphine. Opioids are very addictive when used by healthy persons, conversely the occurrence of an opioid addiction seems very low when patients suffering from cancer are treated with morphine. We investigated the reinforcing properties of morphine in the place preference paradigm on a new model of mice suffering from a cancer pain induced by syngenic melanoma cells injected in the hind paw. These data were compared with mice suffering either from a short-term- or a chronic-inflammatory pain induced respectively by injection of carrageenan or complete Freund's adjuvant. Remarkably, mice suffering from cancer pain or chronic inflammatory pain did not develop any preference for the environment associated with the injection of morphine. In mice injected with melanoma cells, the specific binding of [(125)I]EYWSLAAPQRF-NH(2), an agonist of neuropeptide FF(2) receptors, was increased in several brain areas involved in the rewarding properties of opiates, including the shell of the nucleus accumbens, the major islands of Calleja, the ventral endopiriform nucleus and the amygdaloid area. Our study is the first to reveal a modification of morphine rewarding properties under cancer pain in rodents. We postulate that anti-opioid neuropeptides might contribute to the suppression of morphine rewarding effects in this murine model of cancer pain.
authors.affiliation: Université de Toulouse, Centre de Recherches sur la Cognition Animale, CNRS UMR 5169 Université Paul Sabatier, UFR SVT Bât 4R3b3, 118 route de Narbonne 31062 Toulouse, France.
authors.forename: A
authors.initials: A
authors.lastname: Betourne
authors.forename: J
authors.initials: J
authors.lastname: Familiades
authors.forename: L
authors.initials: L
authors.lastname: Lacassagne
authors.forename: H
authors.initials: H
authors.lastname: Halley
authors.forename: M
authors.initials: M
authors.lastname: Cazales
authors.forename: B
authors.initials: B
authors.lastname: Ducommun
authors.forename: J-M
authors.initials: JM
authors.lastname: Lassalle
authors.forename: J-M
authors.initials: JM
authors.lastname: Zajac
authors.forename: B
authors.initials: B
authors.lastname: Frances
mesh_terms: D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D001345:Autoradiography; D001522:Behavior, Animal / Q000187:drug effects; D002908:Chronic Disease; D003216:Conditioning, Operant / Q000187:drug effects; D004487:Edema / Q000473:pathology; D005260:Female; D005528:Foot / Q000473:pathology; D007249:Inflammation / Q000150:complications* / Q000473:pathology / Q000523:psychology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009020:Morphine / Q000494:pharmacology*; D009042:Motivation; D009043:Motor Activity / Q000187:drug effects; D009369:Neoplasms / Q000150:complications* / Q000473:pathology / Q000523:psychology*; D010146:Pain / Q000188:drug therapy* / Q000209:etiology / Q000523:psychology*; D010147:Pain Measurement / Q000187:drug effects; D018013:Receptors, Neuropeptide / Q000187:drug effects*
chemical_list: D000701:Analgesics, Opioid; D018013:Receptors, Neuropeptide; C083929:neuropeptide FF receptor; D009020:Morphine