Behavioral economics of food reinforcement and the effects of prefeeding, extinction, and eticlopride in dopamine D2 receptor mutant mice

Paul L. Soto, David K. Grandy, Steven R. Hursh, Jonathan L. Katz

    Research output: Contribution to journalArticle

    12 Scopus citations

    Abstract

    Rationale Several studies have investigated the reinforcing effects of food in genetically engineered mice lacking dopamine D2 receptors (DA D2Rs); however, behavioral economic analyses quantifying reinforcement have not been conducted. Objective The role of DA D2Rs in food reinforcement was examined by comparing responding under various fixedratio (FR) schedules of reinforcement, and effects of extinction, satiation, and the DA D2R antagonist eticlopride, in mice with and without genetic deletions of the receptor. Results Response rates of DA D 2R knockout (KO) mice were generally lower than those of littermate wild-type (WT) and heterozygous (HET) mice. The demand curve (consumption vs. FR value) for KO mice decreased more steeply than that of HET or WT mice, suggesting that reinforcing effectiveness is decreased with DA D2R deletion. Prefeeding decreased, whereas extinction increased overall response rates as a proportion of baseline, with no significant genotype differences. Both (+)- and (-)-eticlopride dose-dependently decreased responding in all genotypes with (-)-eticlopride more potent than (+)-eticlopride in all but KO mice. The enantiomers were equipotent in KO mice, and similar in potency to (+)-eticlopride in WT and HET mice. Conclusions That prefeeding and extinction did not vary across genotypes indicates a lack of involvement of DA D 2Rs in these processes. Differences between (-)-eticlopride effects and extinction indicate that DA D2R blockade does not mimic extinction. The maintenance of responding in KO mice indicates that the DA D2R is not necessary for reinforcement. However, the economic analysis indicates that the DA D2R contributes substantially to the effectiveness of food reinforcement.

    Original languageEnglish (US)
    Pages (from-to)775-784
    Number of pages10
    JournalPsychopharmacology
    Volume215
    Issue number4
    DOIs
    StatePublished - Jun 2011

    Keywords

    • Behavioral economics
    • Eticlopride
    • Fixed-ratio schedule of reinforcement
    • Knockout mice

    ASJC Scopus subject areas

    • Pharmacology

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