title: Hyperdopaminergic mutant mice have higher "wanting" but not "liking" for sweet rewards.
abstract: What is the role of dopamine in natural rewards? A genetic mutant approach was taken to examine the consequences of elevated synaptic dopamine on (1) spontaneous food and water intake, (2) incentive motivation and learning to obtain a palatable sweet reward in a runway task, and (3) affective "liking" reactions elicited by the taste of sucrose. A dopamine transporter (DAT) knockdown mutation that preserves only 10% of normal DAT, and therefore causes mutant mice to have 70% elevated levels of synaptic dopamine, was used to identify dopamine effects on food intake and reward. We found that hyperdopaminergic DAT knockdown mutant mice have higher food and water intake. In a runway task, they demonstrated enhanced acquisition and greater incentive performance for a sweet reward. Hyperdopaminergic mutant mice leave the start box more quickly than wild-type mice, require fewer trials to learn, pause less often in the runway, resist distractions better, and proceed more directly to the goal. Those observations suggest that hyperdopaminergic mutant mice attribute greater incentive salience ("wanting") to a sweet reward in the runway test. But sucrose taste fails to elicit higher orofacial "liking" reactions from mutant mice in an affective taste reactivity test. These results indicate that chronically elevated extracellular dopamine facilitates "wanting" and learning of an incentive motivation task for a sweet reward, but elevated dopamine does not increase "liking" reactions to the hedonic impact of sweet tastes.
authors.affiliation: Department of Psychology, University of Michigan, Ann Arbor, Michigan 48109-1109, USA. pesu@umich.edu
authors.forename: Susana
authors.initials: S
authors.lastname: Peciña
authors.forename: Barbara
authors.initials: B
authors.lastname: Cagniard
authors.forename: Kent C
authors.initials: KC
authors.lastname: Berridge
authors.forename: J Wayne
authors.initials: JW
authors.lastname: Aldridge
authors.forename: Xiaoxi
authors.initials: X
authors.lastname: Zhuang
mesh_terms: D000818:Animals; D001070:Appetitive Behavior / Q000187:drug effects / Q000502:physiology*; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D001835:Body Weight / Q000235:genetics; D004298:Dopamine / Q000235:genetics / Q000378:metabolism*; D050483:Dopamine Plasma Membrane Transport Proteins; D004326:Drinking / Q000235:genetics; D004435:Eating / Q000235:genetics; D005106:Exploratory Behavior / Q000502:physiology; D045604:Extracellular Fluid / Q000378:metabolism; D005149:Facial Expression; D007858:Learning / Q000502:physiology; D008297:Male; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008818:Mice, Neurologic Mutants; D009154:Mutation; D009419:Nerve Tissue Proteins; D012201:Reward; D013268:Stimulation, Chemical; D013395:Sucrose / Q000494:pharmacology; D013569:Synapses / Q000378:metabolism; D013649:Taste / Q000187:drug effects / Q000235:genetics / Q000502:physiology*
chemical_list: D050483:Dopamine Plasma Membrane Transport Proteins; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; C493215:Slc6a3 protein, mouse; D013395:Sucrose; D004298:Dopamine