Chunk #23 — 2 Brain Function Responses to Acute Nicotine Administration and Cigarette Smoking — 2.4 Functional Imaging of Nicotinic Acetylcholine Receptors (nAChRs)

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In vivo brain imaging of human exposure to nicotine and tobacco.

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In a recent study (Brody et al. 2006), human cigarette smokers were studied using 2-FA and PET scanning. In this study, only one to two puffs of a cigarette resulted in 50% occupancy of brain α4β2 nAChRs, and this occupancy lasted for at least 3.1 h after smoking. Smoking a full cigarette resulted in 88% occupancy, and was accompanied by a reduction in cigarette craving. Binding of nicotine to α4β2 nAChR causes desensitization of these receptors, and this 2-FA PET study indicated that smoking may lead to withdrawal alleviation by maintaining nAChRs in the desensitized state.