In vivo brain imaging of human exposure to nicotine and tobacco.
In vivo brain imaging of human exposure to nicotine and tobacco.
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DOI：
10.1007/978-3-540-69248-5_6
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发表时间：
2009
影响因子：
--
通讯作者：
Brody AL
中科院分区：
文献类型：
--
作者：
Sharma A;Brody AL
虽然大多数吸烟者都支持戒烟的愿望，但只有14%-49%的人会在6个月或更长时间的治疗后戒烟。更多地了解吸烟对大脑功能的影响可能会导致改善对这种情况的药物和行为干预。研究小组使用功能成像研究了急性和慢性尼古丁/香烟暴露对大脑活动的影响；本章的目的是综合此类研究的结果，并提出吸烟者大脑功能的连贯模型。急性给予尼古丁/吸烟的反应包括：全球大脑活动减少；前额叶皮质、丘脑和视觉系统激活；在视觉认知任务中丘脑和视觉皮质激活；腹侧纹状体/伏隔核多巴胺(DA)浓度增加。对慢性尼古丁/香烟暴露的反应包括：基底节单胺氧化酶(MAO)A和B活性降低，丘脑和壳核中α-4、β-2烟碱型乙酰胆碱受体(NAChR)的可获得性减少(伴随着这些受体的整体上调)。这些发现表明，吸烟通过直接刺激nAChRs，或通过DA释放或MAO抑制间接刺激，或这些因素和可能的其他因素的组合，通过皮质-基底节-丘脑环路增强神经传递。这一回路的激活可能与吸烟对烟草依赖吸烟者的影响有关，如改善注意力表现、情绪、焦虑和易怒。
While most cigarette smokers endorse a desire to quit smoking, only 14–49% will achieve abstinence after 6 months or more of treatment. A greater understanding of the effects of smoking on brain function may result in improved pharmacological and behavioral interventions for this condition. Research groups have examined the effects of acute and chronic nicotine/cigarette exposure on brain activity using functional imaging; the purpose of this chapter is to synthesize findings from such studies and present a coherent model of brain function in smokers. Responses to acute administration of nicotine/smoking include reduced global brain activity; activation of the prefrontal cortex, thalamus, and visual system; activation of the thalamus and visual cortex during visual cognitive tasks; and increased dopamine (DA) concentration in the ventral striatum/nucleus accumbens. Responses to chronic nicotine/cigarette exposure include decreased monoamine oxidase (MAO) A and B activity in the basal ganglia and a reduction in α4β2 nicotinic acetylcholine receptor (nAChR) availability in the thalamus and putamen (accompanied by an overall upregulation of these receptors). These findings indicate that smoking enhances neurotransmission through cortico–basal ganglia–thalamic circuits by direct stimulation of nAChRs, indirect stimulation via DA release or MAO inhibition, or a combination of these and possibly other factors. Activation of this circuitry may be responsible for the effects of smoking seen in tobacco-dependent smokers, such as improvements in attentional performance, mood, anxiety, and irritability.