title: Rimonabant's reductive effects on high densities of food reinforcement, but not palatability, in lean and obese Zucker rats.
abstract: BACKGROUND
  Cannabinoid antagonists purportedly have greater effects in reducing the intake of highly palatable food compared to less palatable food. However, this assertion is based on free-feeding studies in which the amount of palatable food eaten under baseline conditions is often confounded with other variables, such as unequal access to both food options and differences in qualitative features of the foods.
  
  
  OBJECTIVE
  We attempted to reduce these confounds by using a model of choice that programmed the delivery rates of sucrose and carrot-flavored pellets.
  
  
  METHODS
  Lever pressing of ten lean (Fa/Fa or Fa/fa) and ten obese (fa/fa) Zucker rats was placed under three conditions in which programmed ratios for food pellets on two levers were 5:1, 1:1, and 1:5. In phase 1, responses on the two levers produced one type of pellet (sucrose or carrot); in phase 2, responses on one lever produced sucrose pellets and on the other lever produced carrot pellets. After responses stabilized under each food ratio, acute doses of rimonabant (0, 3, and 10 mg/kg) were administered before experimental sessions. The number of reinforcers and responses earned per session under each ratio and from each lever was compared.
  
  
  CONCLUSIONS
  Rimonabant reduced reinforcers in 1:5 and 5:1 food ratios in phase 1, and across all ratios in phase 2. Rimonabant reduced sucrose and carrot-flavored pellet consumption similarly; rimonabant did not affect bias toward sucrose, but increased sensitivity to amount differences in lean rats. This suggests that relative amount of food, not palatability, may be an important behavioral mechanism in the effects of rimonabant.
authors.affiliation: Department of Psychology, Idaho State University, Stop 8112, Pocatello, ID, USA.
authors.forename: Jessica L
authors.initials: JL
authors.lastname: Buckley
authors.forename: Erin B
authors.initials: EB
authors.lastname: Rasmussen
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D002755:Choice Behavior / Q000187:drug effects; D004435:Eating / Q000187:drug effects*; D005247:Feeding Behavior / Q000187:drug effects*; D005518:Food Preferences / Q000187:drug effects*; D008297:Male; D009765:Obesity; D010880:Piperidines / Q000494:pharmacology*; D011720:Pyrazoles / Q000494:pharmacology*; D051381:Rats; D011924:Rats, Zucker; D012055:Reinforcement Schedule; D012054:Reinforcement, Psychology; D000077285:Rimonabant
chemical_list: D010880:Piperidines; D011720:Pyrazoles; D000077285:Rimonabant