title: Decreased rates of operant food self-administration are associated with reward deficits in high-fat feeding mice.
abstract: OBJECTIVE
  Highly palatable foods behave as appetitive reinforcers and tend to be consumed compulsively. Nevertheless, the motivation for this kind of diets in experimental diet-induced obesity models has not been well established. Our hypothesis is that obesity caused by a regular consumption of high-fat diet (HFD) occurs concomitantly with the inhibition of food reward. The ultimate goal of our study was to further analyze the extent to which the perception of food as an appetitive reinforcer is a necessary condition for obesity.
  
  
  METHODS
  We have evaluated the influence of HFD on operant food self-administration (FSA) during a whole light-dark (12-12-h) cycle in mice that consumed HFD either during 1, 4 or 8 weeks. The study has been complemented by a two-bottle free-choice assay between tap water and sweetened drinks.
  
  
  RESULTS
  These data show that both 4- and 8-week HFD treatments induced a significant decrease in operant FSA rate. Moreover, HFD impaired the sweetened-conditioned flavor preference in the two-bottle choice assay.
  
  
  CONCLUSIONS
  Our results, showing a reduction in how hard an animal is willing to work for food reinforcers, provide evidence that chronic consumption of HFD negatively contributes to the incentive motivation to acquire food/drink reinforcers. We demonstrate that energy homeostasis imbalance triggered by HFD is associated with the inhibition of hedonic feeding.
authors.affiliation: Departamento de Psicología Básica I, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), Madrid, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Íbias
authors.affiliation: Departamento de Psicología Básica I, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), Madrid, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Miguéns
authors.affiliation: Laboratorio de Farmacología, Departamento de Ciencias Farmacéuticas y de la Salud, Facultad de Farmacia, Universidad CEU-San Pablo, Campus de Montepríncipe, Boadilla del Monte, 28668, Madrid, Spain.
authors.forename: Danila
authors.initials: D
authors.lastname: Del Rio
authors.affiliation: Laboratorio de Farmacología, Departamento de Ciencias Farmacéuticas y de la Salud, Facultad de Farmacia, Universidad CEU-San Pablo, Campus de Montepríncipe, Boadilla del Monte, 28668, Madrid, Spain.|Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Ismael
authors.initials: I
authors.lastname: Valladolid-Acebes
authors.affiliation: Laboratorio de Farmacología, Departamento de Ciencias Farmacéuticas y de la Salud, Facultad de Farmacia, Universidad CEU-San Pablo, Campus de Montepríncipe, Boadilla del Monte, 28668, Madrid, Spain.|Departamento de Biologia Celular, Instituto de Biologia, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Paula
authors.initials: P
authors.lastname: Stucchi
authors.affiliation: Departamento de Psicobiología, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), Madrid, Spain.
authors.forename: Emilio
authors.initials: E
authors.lastname: Ambrosio
authors.affiliation: Laboratorio de Farmacología, Departamento de Ciencias Farmacéuticas y de la Salud, Facultad de Farmacia, Universidad CEU-San Pablo, Campus de Montepríncipe, Boadilla del Monte, 28668, Madrid, Spain.
authors.forename: Miriam
authors.initials: M
authors.lastname: Martín
authors.affiliation: Laboratorio de Farmacología, Departamento de Ciencias Farmacéuticas y de la Salud, Facultad de Farmacia, Universidad CEU-San Pablo, Campus de Montepríncipe, Boadilla del Monte, 28668, Madrid, Spain.
authors.forename: Lidia
authors.initials: L
authors.lastname: Morales
authors.affiliation: Laboratorio de Farmacología, Departamento de Ciencias Farmacéuticas y de la Salud, Facultad de Farmacia, Universidad CEU-San Pablo, Campus de Montepríncipe, Boadilla del Monte, 28668, Madrid, Spain.
authors.forename: Mariano
authors.initials: M
authors.lastname: Ruiz-Gayo
authors.affiliation: Laboratorio de Farmacología, Departamento de Ciencias Farmacéuticas y de la Salud, Facultad de Farmacia, Universidad CEU-San Pablo, Campus de Montepríncipe, Boadilla del Monte, 28668, Madrid, Spain. nolmo@ceu.es.
authors.forename: Nuria
authors.initials: N
authors.lastname: Del Olmo
mesh_terms: D000818:Animals; D002755:Choice Behavior; D066249:Craving / Q000502:physiology; D059305:Diet, High-Fat; D004040:Dietary Carbohydrates / Q000008:administration & dosage / Q000032:analysis; D004041:Dietary Fats / Q000008:administration & dosage* / Q000032:analysis; D004043:Dietary Fiber / Q000008:administration & dosage / Q000032:analysis; D004044:Dietary Proteins / Q000008:administration & dosage / Q000032:analysis; D002149:Energy Intake; D005247:Feeding Behavior; D005518:Food Preferences; D006706:Homeostasis; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D064427:Nutritive Sweeteners / Q000008:administration & dosage / Q000032:analysis; D009765:Obesity / Q000139:chemically induced; D012201:Reward; D012646:Self Administration
chemical_list: D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004043:Dietary Fiber; D004044:Dietary Proteins; D064427:Nutritive Sweeteners
keywords: Food self-administration; High-fat diets; Motivation; Obesity; Reward; Two-bottle choice