Reinforcing and neurochemical effects of cannabinoid CB1 receptor agonists, but not cocaine, are altered by an adenosine A2A receptor antagonist

Zuzana Justinová, Sergi Ferré, Godfrey H. Redhi, Paola Mascia, Jessica Stroik, Davide Quarta, Sevil Yasar, Christa E. Müller, Rafael Franco, Steven R. Goldberg

Research output: Contribution to journalArticle

Abstract

Several recent studies suggest functional and molecular interactions between striatal adenosine A 2A and cannabinoid CB 1 receptors. Here, we demonstrate that A 2A receptors selectively modulate reinforcing effects of cannabinoids. We studied effects of A 2A receptor blockade on the reinforcing effects of delta-9-tetrahydrocannabinol (THC) and the endogenous CB 1 receptor ligand anandamide under a fixed-ratio schedule of intravenous drug injection in squirrel monkeys. A low dose of the selective adenosine A 2A receptor antagonist MSX-3 (1 mg/kg) caused downward shifts of THC and anandamide dose-response curves. In contrast, a higher dose of MSX-3 (3 mg/kg) shifted THC and anandamide dose-response curves to the left. MSX-3 did not modify cocaine or food pellet self-administration. Also, MSX-3 neither promoted reinstatement of extinguished drug-seeking behavior nor altered reinstatement of drug-seeking behavior by non-contingent priming injections of THC. Finally, using in vivo microdialysis in freely-moving rats, a behaviorally active dose of MSX-3 significantly counteracted THC-induced, but not cocaine-induced, increases in extracellular dopamine levels in the nucleus accumbens shell. The significant and selective results obtained with the lower dose of MSX-3 suggest that adenosine A 2A antagonists acting preferentially at presynaptic A 2A receptors might selectively reduce reinforcing effects of cannabinoids that lead to their abuse. However, the appearance of potentiating rather than suppressing effects on cannabinoid reinforcement at the higher dose of MSX-3 would likely preclude the use of such a compound as a medication for cannabis abuse. Adenosine A 2A antagonists with more selectivity for presynaptic versus postsynaptic receptors could be potential medications for treatment of cannabis abuse. Addiction Biology

Original languageEnglish (US)
Pages (from-to)405-415
Number of pages11
JournalAddiction Biology
Volume16
Issue number3
DOIs
Publication statusPublished - Jul 2011

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Keywords

  • Adenosine A2A receptor
  • Anandamide
  • Dopamine
  • Reinforcement
  • Reinstatement
  • THC

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Psychiatry and Mental health
  • Pharmacology

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