Lebargy F
Département des maladies respiratoires et allergiques, CHU Maison Blanche, 45 rue Cognacq-Jay, 51092 Reims, France.
Rev Pneumol Clin. 2000 Jun;56(3):177-83.
Nicotine is the principle alkaloid in tobacco and is considered to be responsible for tobacco dependence due to its psychoactive properties and its capacity to induce self-administration behavior in animals. Its action affects the brain where it binds to specific nicotinic receptors distributed on the mesolimbic and mesocortial dopaminergic pathways. Dopamine release by the nerve endings on these pathways provokes activation of the cerebral response. Acute stimulation with nicotine provokes a rise in cerebral dopamine levels in the accumbens. Dopamine release is greatly lowered in animals having undergone chronic exposure to nicotine, suggesting desensitization of the nicotinic receptors. In the regular smoker, there is an increase in the number of cerebral nicotinic receptors which would be a neuroadaptation response to desensitization. Reduction in the serum nicotine level favors resensitization of the nicotinic receptors and their vacuity would be the cause of the withdrawal syndrome. In therapeutics, nicotinic substitutes can effectively suppress the withdrawal syndrome and lead to abstinence rates to the order of 20 to 25% at one year. Psychotropes can also be effective to help patients stop smoking. Their mechanism of action is not clearly established but most would act by increasing the level of cerebral dopamine. They are used independently of their antidepressor effect with abstinence rates to the order of 25 to 30% at one year. Their combination with nicotinic substitutes can increase the rate of success.
尼古丁是烟草中的主要生物碱，因其具有精神活性以及能够在动物身上诱发自我给药行为，被认为是导致烟草依赖的原因。其作用于大脑，与分布在中脑边缘和中脑皮质多巴胺能通路上的特定烟碱受体结合。这些通路上神经末梢释放的多巴胺会激发大脑反应的激活。尼古丁的急性刺激会导致伏隔核中脑多巴胺水平升高。在长期接触尼古丁的动物中，多巴胺释放大幅降低，这表明烟碱受体脱敏。在经常吸烟的人中，大脑烟碱受体数量增加，这可能是对脱敏的一种神经适应性反应。血清尼古丁水平降低有利于烟碱受体重新敏感化，而其空缺可能是戒断综合征的原因。在治疗方面，烟碱替代品可以有效抑制戒断综合征，一年的戒烟率可达20%至25%左右。精神药物也可以有效帮助患者戒烟。它们的作用机制尚未明确确立，但大多数可能通过提高大脑多巴胺水平起作用。它们独立于抗抑郁作用使用，一年的戒烟率约为25%至30%。它们与烟碱替代品联合使用可以提高成功率。
