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The effect of nicotine on striatal dopamine release in man: A 11Craclopride PET study.

, , , , and . Synapse (New York, N.Y.), 61 (8): 637--645 (August 2007)
DOI: 10.1002/syn.20419

Abstract

In common with many addictive substances and behaviors nicotine activates the mesolimbic dopaminergic system. Brain microdialysis studies in rodents have consistently shown increases in extrasynaptic DA levels in the striatum after administration of nicotine but PET experiments in primates have given contradicting results. A recent PET study assessing the effect of smoking in humans showed no change in (11)Craclopride binding in the brain, but did find that "hedonia" correlated with a reduction in (11)Craclopride binding suggesting that DA may mediate the positive reinforcing effects of nicotine. In this experiment we measured the effect of nicotine, administered via a nasal spray, on DA release using (11)Craclopride PET, in 10 regular smokers. There was no overall change in (11)Craclopride binding after nicotine administration in any of the striatal regions examined. However, the individual change in (11)Craclopride binding correlated with change in subjective measures of ämused" and "happiness" in the associative striatum (AST) and sensorimotor striatum (SMST). Nicotine concentration correlated negatively with change in BP in the limbic striatum. Nicotine had significant effects on cardiovascular measures including pulse rate, systolic blood pressure (BPr), and diastolic BPr. Baseline (11)Craclopride binding potential (BP) in the AST correlated negatively with the Fagerström score, an index of nicotine dependence. These results support a role for the DA system in nicotine addiction, but reveal a more complex relationship than suggested by studies in animals.

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