title: Hypoalgesia Induced by Reward Devaluation in Rats.
abstract: Reduced sensitivity to physical pain (hypoalgesia) has been reported after events involving reward devaluation. Reward devaluation was implemented in a consummatory successive negative contrast (cSNC) task. Food-deprived Wistar rats had access to 32% sucrose during 16 sessions followed by access to 4% sucrose during 3 additional sessions. An unshifted control group had access to 4% sucrose throughout the 19 sessions. Pain sensitivity was measured using von Frey filaments (Experiment 1) and Hargreaves thermal stimuli (Experiment 2) in pretraining baseline, 5 min, and 300 min after either the first (session 17) or second (session 18) devaluation session in the cSNC situation. Sucrose consumption was lower in downshifted groups relative to unshifted groups during postshift sessions-the cSNC effect. Hypoalgesia was observed in downshifted groups relative to unshifted controls when pain sensitivity was assessed 5 min after either the first or second devaluation session, regardless of the pain sensitivity test used. Both pain sensitivity tests yielded evidence of hypoalgesia 300 min after the second downshift session, but not 300 min after the first devaluation session. Whereas hypoalgesia was previously shown only after the second devaluation session, here we report evidence of hypoalgesia after both the first and second devaluation sessions using mechanical and thermal nociceptive stimuli. Moreover, the hypoalgesia observed 300 min after the second devaluation session in both experiments provides unique evidence of the effects of reward loss on sensitivity to physical pain 5 hours after the loss episode. The underlying neurobehavioral mechanisms remain to be identified.
authors.affiliation: Department of Pharmacology, Biomedical Research Center (CIBM) and Institute of Neuroscience, Faculty of Medicine, University of Granada, Campus Ciencias de la Salud, 18016, Granada, Spain.|Department of Psychobiology and Research Center for Mind, Brain, and Behavior (CIMCYC), University of Granada, Faculty of Psychology, Campus Cartuja, 18071, Granada, Spain.
authors.forename: Ana María
authors.initials: AM
authors.lastname: Jiménez-García
authors.affiliation: Department of Pharmacology, Biomedical Research Center (CIBM) and Institute of Neuroscience, Faculty of Medicine, University of Granada, Campus Ciencias de la Salud, 18016, Granada, Spain.|Department of Psychobiology and Research Center for Mind, Brain, and Behavior (CIMCYC), University of Granada, Faculty of Psychology, Campus Cartuja, 18071, Granada, Spain.
authors.forename: Leandro
authors.initials: L
authors.lastname: Ruíz-Leyva
authors.affiliation: Department of Pharmacology, Biomedical Research Center (CIBM) and Institute of Neuroscience, Faculty of Medicine, University of Granada, Campus Ciencias de la Salud, 18016, Granada, Spain.
authors.forename: Cruz Miguel
authors.initials: CM
authors.lastname: Cendán
authors.affiliation: Department of Psychology, University of Jaén, Campus Las Lagunillas, 23071, Jaén, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Torres
authors.affiliation: Department of Psychology, Texas Christian University, Fort Worth, TX, 76129, United States of America.
authors.forename: Mauricio R
authors.initials: MR
authors.lastname: Papini
authors.affiliation: Department of Psychobiology and Research Center for Mind, Brain, and Behavior (CIMCYC), University of Granada, Faculty of Psychology, Campus Cartuja, 18071, Granada, Spain.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Morón
mesh_terms: D000818:Animals; D003216:Conditioning, Operant; D003259:Consummatory Behavior / Q000502:physiology; D008297:Male; D010146:Pain / Q000473:pathology*; D051381:Rats; D017208:Rats, Wistar; D012201:Reward; D013395:Sucrose / Q000008:administration & dosage
chemical_list: D013395:Sucrose