The Journal of Neuroscience, August 1, 2002, 22(15):6321-6324
Caffeine Induces Dopamine and Glutamate Release in the Shell of the Nucleus Accumbens
Marcello Solinas1, Sergi Ferré1, Zhi-Bing You2, Marzena Karcz-Kubicha1, Patrizia Popoli3, and Steven R. Goldberg1
Sections of 1 Preclinical Pharmacology and 2 Behavioral Neuroscience, Behavioral Neuroscience Branch, National Institute on Drug Abuse, National Institutes of Health Intramural Research Program, Baltimore, Maryland 21224, and 3 Department of Pharmacology, Istituto Superiore di Sanita, 00161 Rome, Italy
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.
Key words: caffeine; adenosine; dopamine; glutamate; accumbens; microdialysis
BTW, it's very well established that opioids increase DAergic transmission in the nucleus accumbens by inhibiting the GABAergic inhibition from the ventral tegmental area. All opioid receptors are inhibitory.
Those who're interested might want to check out my archive of neurobiology/pharmacology citations, abstracts and papers on
http://www.anakata.hack.se/papers/ .
[ 12 August 2002: Message edited by: wilson ]