title: Differential involvement of the opioid receptor antagonist naloxone in motivational and hedonic aspects of reward.
abstract: In the present study dose-dependent effects of the opioid receptor antagonist naloxone were investigated on the rewarding effects of sweetened condensed milk (SCM) in four behavioral paradigms addressing hedonic, consummatory as well as motivational aspects of a reward: odour-conditioned pleasure attenuation of the acoustic startle response (PAS), conditioned place preference (CPP), voluntary consumption in a limited access paradigm, as well as break point determination in a progressive ratio (PR) task. A dose-dependent reduction in reward-related behavior was observed in all paradigms, with exception of the break point in the PR task, which was not affected by naloxone at all. CPP for SCM was only affected by the highest dose of naloxone. The present results indicate that naloxone is more effective in suppressing the hedonic than motivational aspects of reward, further supporting the involvement of the endogenous opioid system in the mediation of hedonic properties of food reward.
authors.affiliation: Central Institute of Mental Health (ZI), Department of Psychopharmacology, Mannheim, Germany. miriam.schneider@zi-mannheim.de
authors.forename: Miriam
authors.initials: M
authors.lastname: Schneider
authors.forename: Verena
authors.initials: V
authors.lastname: Heise
authors.forename: Rainer
authors.initials: R
authors.lastname: Spanagel
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D003216:Conditioning, Operant / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005518:Food Preferences / Q000187:drug effects*; D008297:Male; D009042:Motivation / Q000187:drug effects*; D009270:Naloxone / Q000494:pharmacology*; D009292:Narcotic Antagonists / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D013216:Reflex, Startle / Q000187:drug effects; D012201:Reward; D013549:Sweetening Agents / Q000008:administration & dosage
chemical_list: D009292:Narcotic Antagonists; D013549:Sweetening Agents; D009270:Naloxone