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Title: Caffeine increases striatal dopamine D2/D3 receptor availability in the human brain

Caffeine, the most widely consumed psychoactive substance in the world, is used to promote wakefulness and enhance alertness. Like other wake-promoting drugs (stimulants and modafinil), caffeine enhances dopamine (DA) signaling in the brain, which it does predominantly by antagonizing adenosine A2A receptors (A2AR). However, it is unclear if caffeine, at the doses consumed by humans, increases DA release or whether it modulates the functions of postsynaptic DA receptors through its interaction with adenosine receptors, which modulate them. We used positron emission tomography and [11C]raclopride (DA D2/D3 receptor radioligand sensitive to endogenous DA) to assess if caffeine increased DA release in striatum in 20 healthy controls. Caffeine (300mg p.o.) significantly increased the availability of D2/D3 receptors in putamen and ventral striatum, but not in caudate, when compared with placebo. In addition, caffeine-induced increases in D2/D3 receptor availability in the ventral striatum were associated with caffeine-induced increases in alertness. Our findings indicate that in the human brain, caffeine, at doses typically consumed, increases the availability of DA D2/D3 receptors, which indicates that caffeine does not increase DA in the striatum for this would have decreased D2/D3 receptor availability. Instead, we interpret our findings to reflect an increase in D2/D3 receptor levels inmore » striatum with caffeine (or changes in affinity). Furthermore, the association between increases in D2/D3 receptor availability in ventral striatum and alertness suggests that caffeine might enhance arousal, in part, by upregulating D2/D3 receptors.« less
Authors:
 [1] ;  [1] ;  [2] ;  [2] ;  [2] ;  [2] ;  [1] ;  [3] ;  [4] ;  [1]
  1. National Institute on Alcohol Abuses and Alcoholism, Bethesda, MD (United States)
  2. Brookhaven National Lab. (BNL), Upton, NY (United States)
  3. Univ. of Barcelona, Barcelona (Spain)
  4. National Institute on Drug Abuse, Baltimore, MD (United States)
Publication Date:
OSTI Identifier:
1261638
Type:
Accepted Manuscript
Journal Name:
Translational Psychiatry
Additional Journal Information:
Journal Volume: 5; Journal Issue: 4; Journal ID: ISSN 2158-3188
Publisher:
Nature Publishing Group
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES caffeine; dopamine