Addiction-related alterations in D1 and D2 dopamine receptor behavioral responses following chronic cocaine self-administration

Scott Edwards, Kimberly N. Whisler, Dwain C. Fuller, Paul J. Orsulak, David W. Self

Research output: Contribution to journalArticle

64 Scopus citations

Abstract

The cocaine-addicted phenotype can be modeled in rats based on individual differences in preferred levels of cocaine intake and a propensity for relapse in withdrawal. These cocaine-taking and -seeking behaviors are strongly but differentially regulated by postsynaptic D1 and D2 receptors in the mesolimbic dopamine system. Thus, we determined whether addiction-related differences in cocaine self-administration would be related to differential sensitivity in functional D1 and D2 receptor responses. Using a population of 40 outbred Sprague-Dawley rats trained to self-administer cocaine for 3 weeks, we found that animals with higher preferred levels of cocaine intake exhibited a vertical and rightward shift in the self-administration dose-response function, and were more resistant to extinction from cocaine self-administration, similar to phenotypic changes reported in other models of cocaine addiction. After 3 weeks of withdrawal from cocaine self-administration, high intake rats were subsensitive to the ability of the D1 agonist SKF 81297 to inhibit cocaine-seeking behavior elicited by cocaine priming, but supersensitive to cocaine seeking triggered by the D2 agonist quinpirole, when compared to low intake rats. Additionally, high intake rats developed profound increases in locomotor responses to D2 receptor challenge from early to late withdrawal times, whereas low intake rats developed increased responsiveness to D 1 receptor challenge. In a second experiment, responses to the mixed D1/D2 agonist apomorphine and the NMDA glutamate receptor antagonist MK-801 failed to differ between low and high intake rats. These findings suggest that cocaine addiction is related specifically to differential alterations in functional D1 and D2 receptors and their ability to modulate cocaine-seeking behavior.

Original languageEnglish (US)
Pages (from-to)354-366
Number of pages13
JournalNeuropsychopharmacology
Volume32
Issue number2
DOIs
Publication statusPublished - Feb 2007

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Keywords

  • Craving
  • Mesolimbic dopamine
  • Reinforcement
  • Reinstatement
  • Relapse
  • Reward

ASJC Scopus subject areas

  • Pharmacology

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