Effect of Secondhand Smoke on Occupancy of Nicotinic Acetylcholine Receptors in Brain

CONTEXT Despite progress in tobacco control, secondhand smoke (SHS) exposure remains prevalent worldwide and is implicated in the initiation and maintenance of cigarette smoking. OBJECTIVE To determine whether moderate SHS exposure results in brainα4β2* nicotinic acetylcholine receptor (nAChR) occupancy. DESIGN, SETTING, AND PARTICIPANTS Positron emission tomography scanning and the radiotracer 2-[18F]fluoro-3-(2(S)azetidinylmethoxy) pyridine (also known as 2-[18F]fluoro-A-85380, or 2-FA) were used to determineα4β2* nAChR occupancy from SHS exposure in 24 young adult participants (11 moderately dependent cigarette smokers and 13 nonsmokers). Participants underwent two bolus-plus-continuous-infusion 2-FA positron emission tomography scanning sessions during which they sat in the passenger's seat of a car for 1 hour and either were exposed to moderate SHS or had no SHS exposure. The study took place at an academic positron emission tomography center. MAIN OUTCOME MEASURE Changes induced by SHS in 2-FA specific binding volume of distribution as a measure ofα4β2* nAChR occupancy. RESULTS An overall multivariate analysis of variance using specific binding volume of distribution values revealed a significant main effect of condition (SHS vs control) (F1,22 = 42.5, P