Brain nicotinic acetylcholine receptor occupancy: effect of smoking a denicotinized cigarette.

Published

Journal Article

Our group recently reported that smoking a regular cigarette (1.2-1.4 mg nicotine) resulted in 88% occupancy of brain alpha4beta2* nicotinic acetylcholine receptors (nAChRs). However, this study did not determine whether nicotine inhalation or the many other pharmacological and behavioural factors that occur during smoking resulted in this receptor occupancy. If nicotine is solely responsible for alpha4beta2* nAChR occupancy from smoking, then (as estimated from our previous data) smoking a denicotinized (0.05 mg nicotine) or a low-nicotine (0.6 mg nicotine) cigarette (commonly used for research and clinical purposes) would result in substantial 23% and 78% alpha4beta2* nAChR occupancies, respectively, and a plasma nicotine concentration of 0.87 ng/ml would result in 50% alpha4beta2* nAChR occupancy (EC50). Twenty-four positron emission tomography sessions were performed on tobacco-dependent smokers, using 2-[F-18]fluoro-A-85380 (2-FA), a radiotracer that binds to alpha4beta2* nAChRs. 2-FA displacement was determined from before to 3.1 hours after either: no smoking, smoking a denicotinized cigarette, or smoking a low-nicotine cigarette. Analysis of this PET data revealed that smoking a denicotinized and a low-nicotine cigarette resulted in 26% and 79% alpha4beta2* nAChR occupancies, respectively, across three regions of interest. The EC50 determined from this dataset was 0.75 ng/ml. Given the consistency of findings between our previous study with regular cigarettes and the present study, nicotine inhalation during smoking appears to be solely responsible for alpha4beta2* nAChR occupancy, with other factors (if present at all) having either short-lived or very minor effects. Furthermore, smoking a denicotinized cigarette resulted in substantial nAChR occupancy.

Full Text

Duke Authors

Cited Authors

  • Brody, AL; Mandelkern, MA; Costello, MR; Abrams, AL; Scheibal, D; Farahi, J; London, ED; Olmstead, RE; Rose, JE; Mukhin, AG

Published Date

  • April 2009

Published In

Volume / Issue

  • 12 / 3

Start / End Page

  • 305 - 316

PubMed ID

  • 18706128

Pubmed Central ID

  • 18706128

Electronic International Standard Serial Number (EISSN)

  • 1469-5111

Digital Object Identifier (DOI)

  • 10.1017/S146114570800922X

Language

  • eng

Conference Location

  • England