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Tobacco Smoking and Brain Endogenous Opioid Release: More Than Nicotine Alone.

ABSTRACT: INTRODUCTION:The effects of smoking denicotinized (denic) and average nicotine (avnic) tobacco cigarettes were studied on brain mu opioid receptor binding by positron emission tomography with 11C carfentanil. The results indicated the importance of physiological and psychological effects induced by denic smoking. METHODS:Regional mu opioid binding potential (nondisplaceable binding potential, BPND) was measured in 20 adult male overnight abstinent chronic tobacco smokers. The denic sessions were conducted about 8:00 am followed by avnic sessions about 2 hours later. Venous plasma nicotine levels and scores of craving to smoke were assessed before and after each smoking session. Fagerstrom scores of nicotine dependence were determined. Pearson's and Spearman's correlation tests were used to examine associations between BPND and other smoking parameters. RESULTS:Surprisingly, the very low plasma nicotine peak levels after denic smoking (mean ± SD: 3.3 ± 1.8 ng/mL) were significantly correlated with BPND after denic and avnic smoking. Equally surprising no association was found between nicotine levels after avnic smoking and BPND. Delta craving scores and Fagerstrom scores were correlated with both BPND after denic and avnic in several brain regions. CONCLUSIONS:Very small amounts of nicotine, psychological and behavioral effects of denic smoking appear to have important actions on the endogenous mu opioid system. IMPLICATIONS:Associations between very low venous plasma nicotine levels after denic smoking and regional brain mu opioid receptor availability are a surprising "placebo" effect. Delta craving and Fagerstrom scores were correlated with BPND in several brain regions including amygdala, hippocampus, insula, nucleus accumbens, putamen, and ventral striatum. This study is limited by modest Power (mean 1 - ? = 0.6) for all correlation analyses.

SUBMITTER: Domino EF

PROVIDER: S-EPMC6528147 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature

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Tobacco Smoking and Brain Endogenous Opioid Release: More Than Nicotine Alone.

Domino Edward F EF Hirasawa-Fujita Mika M

Nicotine & tobacco research : official journal of the Society for Research on Nicotine and Tobacco 20190501 6

<h4>Introduction</h4>The effects of smoking denicotinized (denic) and average nicotine (avnic) tobacco cigarettes were studied on brain mu opioid receptor binding by positron emission tomography with 11C carfentanil. The results indicated the importance of physiological and psychological effects induced by denic smoking.<h4>Methods</h4>Regional mu opioid binding potential (nondisplaceable binding potential, BPND) was measured in 20 adult male overnight abstinent chronic tobacco smokers. The deni ...[more]

PMID: 29514324

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Project description:INTRODUCTION:This study investigated the effects of nicotine/tobacco on neural activation during performance of a monetary incentive delay task. AIMS AND METHODS:Prior to each scan, nonsmokers received nicotine or placebo nasal spray, and smokers were smoking satiated or 24-hour withdrawn. During the scan, participants made timed responses to reward-related cues and received feedback. Parameter estimates from cue- and feedback-related activation in medial prefrontal regions and the nucleus accumbens were extracted and underwent within- and between-group analyses. Smokers' nicotine dependence severity was included as a continuous predictor variable for neural activation. RESULTS:Among smokers (n = 21), withdrawal decreased cue-related activation in the supplementary motor area and ventromedial prefrontal cortex, and the difference in activation (satiety > withdrawal) in these regions negatively correlated with nicotine dependence severity (Fagerström Test for Nicotine Dependence). Among nonsmokers (n = 22), nicotine increased the difference in nucleus accumbens activation between rewarded and nonrewarded feedback phases. Tobacco withdrawal and acute nicotine also had widespread effects on activation throughout the brain during the feedback phase. CONCLUSIONS:Acute nicotine in nonsmokers may have increased the salience of feedback information, but produced few effects on reward-related activation overall, perhaps reflecting nicotine's modest, indirect effects on reward processing. Conversely, tobacco withdrawal decreased activation compared with satiety, and this difference between conditions correlated with nicotine dependence severity. This suggests that as smokers become more dependent on nicotine, tobacco withdrawal has a more pronounced effect on reward processing. IMPLICATIONS:Relative to the acute effects of nicotine in nonsmokers, withdrawal from daily tobacco use had more significant effects on reward-related brain activation. This study suggests that the effects of tobacco withdrawal on reward-related brain function interact with subjects' level of nicotine dependence severity. These are potentially important sources of variability that could contribute to smoking cessation outcomes.

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Tobacco Smoking and Brain Endogenous Opioid Release: More Than Nicotine Alone.

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Tobacco Smoking and Brain Endogenous Opioid Release: More Than Nicotine Alone.

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