Mice With Chronically Elevated Dopamine Exhibit Enhanced Motivation, but Not Learning, for a Food Reward

Neuropsychopharmacology. 2006 Jul;31(7):1362-70. doi: 10.1038/sj.npp.1300966. Epub 2005 Nov 23.

Abstract

Dopamine has been critically implicated in learning and motivation, although its precise role remains to be determined. In order to investigate the involvement of dopamine in learning and motivation for a food reward, we used dopamine transporter knockdown mice (DAT KD) that have chronically elevated levels of extracellular dopamine. The present study demonstrates that chronically elevated dopamine enhances tendency to work for a food reward without apparent effects on Pavlovian and operant learning for this reward. The increase in dopamine is associated with elevated levels of dynorphin and Fos B expression in the dorsal caudate-putamen and the core but not the shell subregion of the nucleus accumbens. These data suggest that motivation to work, but not learning, for a food reward appears to be under the critical influence of tonic dopaminergic activity in discrete brain areas relevant for a reward-directed behavior.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Association Learning / physiology
  • Behavior, Animal
  • Cell Count / methods
  • Choice Behavior / physiology
  • Conditioning, Classical / physiology
  • Conditioning, Operant / physiology
  • Dopamine / metabolism*
  • Dopamine Plasma Membrane Transport Proteins / deficiency
  • Dynorphins / genetics
  • Dynorphins / metabolism
  • Eating / genetics
  • Food Deprivation / physiology
  • Food*
  • Gene Expression Regulation / genetics
  • In Situ Hybridization / methods
  • Learning / physiology*
  • Mice
  • Mice, Knockout
  • Motivation*
  • Protein Precursors / genetics
  • Protein Precursors / metabolism
  • Proto-Oncogene Proteins c-fos / genetics
  • Proto-Oncogene Proteins c-fos / metabolism
  • Reward*
  • Time Factors

Substances

  • Dopamine Plasma Membrane Transport Proteins
  • Fosb protein, rat
  • Protein Precursors
  • Proto-Oncogene Proteins c-fos
  • pre-prodynorphin
  • Dynorphins
  • Dopamine