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document
Effects of nicotine on regional cerebral glucose metabolism in awake resting tobacco smokers . Eleven healthy tobacco smoking adult male volunteers of mixed race were tobacco abstinent overnight for this study . In each subject , positron emission tomographic images of regional cerebral metabolism of glucose with [ 18F ] fluorodeoxyglucose were obtained in two conditions in the morning on different days : about 3min after approximately 1-2mg of nasal nicotine spray and after an equivalent volume of an active placebo spray of oleoresin of pepper in a random counterbalanced design . A Siemens/CTI 931/08-12 scanner with the capability of 15 horizontal brain slices was used . The images were further converted into a standard uniform brain format in which the mean data of all 11 subjects were obtained . Images were analysed in stereotactic coordinates using pixel-wise t statistics and a smoothed Gaussian model . Peak plasma nicotine levels varied three-fold and the areas under the curve ( 0-30min ) varied seven-fold among the individual subjects . Nicotine caused a small overall reduction in global cerebral metabolism of glucose but , when the data were normalized , several brain regions showed relative increases in activity . Cerebral structures specifically activated by nicotine ( nicotine minus pepper , Z score > 4.0 ) included : left inferior frontal gyrus , left posterior cingulate gyrus and right thalamus . The visual cortex , including the right and left cuneus and left lateral occipito-temporal gyrus fusiformis , also showed an increase in regional cerebral metabolism of glucose with Z scores > 3 . 6 . Structures with a decrease in regional cerebral metabolism of glucose ( pepper minus nicotine ) were the left insula and right inferior occipital gyrus , with Z scores > 3.5 . Especially important is the fact that the thalamus is activated by nicotine . This is consistent with the high density of nicotinic cholinoceptors in that brain region . However , not all brain regions affected by nicotine are known to have many nicotinic cholinoceptors . The results are discussed in relation to the cognitive effects of nicotine .
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Intervention_Pharmacological
nicotine
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Intervention_Physical
tobacco abstinent
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Intervention_Pharmacological
1-2mg of nasal nicotine spray
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Intervention_Control
after an equivalent volume of an active placebo spray of oleoresin of pepper
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Intervention_Pharmacological
nicotine
4977
Intervention_Pharmacological
Nicotine
4978
Intervention_Pharmacological
nicotine
4979
Intervention_Pharmacological
nicotine
4980
Intervention_Pharmacological
nicotine
4981
Outcome_Physical
regional cerebral glucose metabolism
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Outcome_Other
positron emission tomographic images
4983
Outcome_Physical
cerebral metabolism of glucose
4984
Outcome_Physical
Peak plasma nicotine levels
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Outcome_Physical
global cerebral metabolism of glucose
4986
Outcome_Physical
regional cerebral metabolism of glucose
4987
Outcome_Physical
regional cerebral metabolism of glucose ( pepper
4988
Outcome_Physical
nicotine