Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland; Department of Radiology, University of Turku, Turku, Finland.
Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland; Houston Methodist Research Institute, Houston, Texas.
Biol Psychiatry. 2018 Nov 15;84(10):715-721. doi: 10.1016/j.biopsych.2018.07.009. Epub 2018 Jul 21.
Previous studies showed reduction of brain cannabinoid CB receptors in adults with cannabis and alcohol use disorders. Preclinical data suggest that these receptors also contribute to nicotine reward and dependence. Tobacco smoking may confound clinical studies of psychiatric disorders because many patients with such disorders smoke tobacco. Whether human subjects who smoke tobacco but are otherwise healthy have altered CB receptor binding in brain is unknown.
We measured CB receptors in brains of 18 healthy men who smoke tobacco (frequent chronic cigarette smokers), and 28 healthy men who do not smoke tobacco, using positron emission tomography and [F]FMPEP-d, a radioligand for CB receptors. We collected arterial blood samples during scanning to calculate the distribution volume (V), which is nearly proportional to CB receptor density. Repeated-measures analysis of variance compared V between groups in various brain regions.
Brain CB receptor V was about 20% lower in subjects who smoke tobacco than in subjects who do not. Decreased V was found in all brain regions, but reduction did not correlate with years of smoking, number of cigarettes smoked per day, or measures of nicotine dependence.
Tobacco-smoking healthy men have a widespread reduction of CB receptor density in brain. Reduction of CB receptors appears to be a common feature of substance use disorders. Future clinical studies on the CB receptor should control for tobacco smoking.
先前的研究表明，大麻和酒精使用障碍患者大脑中的大麻素 CB 受体减少。临床前数据表明，这些受体也有助于尼古丁的奖赏和依赖。吸烟可能会干扰精神疾病临床研究，因为许多患有此类疾病的患者吸烟。目前尚不清楚吸烟但其他方面健康的人类受试者的大脑 CB 受体结合是否发生改变。
我们使用正电子发射断层扫描和 [F]FMPEP-d（一种用于 CB 受体的放射性配体），测量了 18 名吸烟（频繁慢性吸烟）的健康男性和 28 名不吸烟的健康男性的大脑 CB 受体。在扫描过程中收集动脉血样，以计算分布容积（V），V 几乎与 CB 受体密度成正比。采用重复测量方差分析比较两组在不同脑区的 V。
吸烟组的大脑 CB 受体 V 比不吸烟组低约 20%。所有脑区均发现 V 降低，但降低与吸烟年限、每日吸烟量或尼古丁依赖测量值无关。
吸烟健康男性的大脑中 CB 受体密度普遍降低。CB 受体的减少似乎是物质使用障碍的共同特征。未来关于 CB 受体的临床研究应控制吸烟。
