Abstract
An increase in the extracellular concentration of dopamine in the nucleus accumbens (NAc) is believed to be one of the main mechanisms involved in the rewarding and motor-activating properties of psychostimulants such as amphetamines and cocaine. Using in vivo microdialysis in freely moving rats, we demonstrate that systemic administration of behaviorally relevant doses of caffeine can preferentially increase extracellular levels of dopamine and glutamate in the shell of the NAc. These effects could be reproduced by the administration of a selective adenosine A1 receptor antagonist but not by a selective adenosine A2A receptor antagonist. This suggests that caffeine, because of its ability to block adenosine A1 receptors, shares neurochemical properties with other psychostimulants, which could contribute to the widespread consumption of caffeine-containing beverages.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Behavior, Animal / drug effects
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Caffeine / pharmacology*
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Dopamine / analysis
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Dopamine / metabolism*
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Dose-Response Relationship, Drug
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Extracellular Space / chemistry
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Extracellular Space / metabolism
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Glutamic Acid / analysis
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Glutamic Acid / metabolism*
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Injections, Intraperitoneal
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Male
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Microdialysis
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Motor Activity / drug effects
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Nucleus Accumbens / drug effects*
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Nucleus Accumbens / metabolism*
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Purinergic P1 Receptor Antagonists
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Pyrimidines / pharmacology
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Rats
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Rats, Sprague-Dawley
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Receptor, Adenosine A2A
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Theophylline / analogs & derivatives*
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Theophylline / pharmacology
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Triazoles / pharmacology
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Wakefulness / drug effects
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Wakefulness / physiology
Substances
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5-amino-7-(2-phenylethyl)-2-(2-furyl)pyrazolo(4,3-e)-1,2,4-triazolo(1,5-c)pyrimidine
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Purinergic P1 Receptor Antagonists
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Pyrimidines
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Receptor, Adenosine A2A
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Triazoles
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8-cyclopentyl-1,3-dimethylxanthine
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Caffeine
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Glutamic Acid
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Theophylline
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Dopamine