Di Chiara G
Department of Toxicology, University of Cagliari, Italy.
Drug Alcohol Depend. 1995 May;38(2):95-137. doi: 10.1016/0376-8716(95)01118-i.
Drugs of abuse share with conventional reinforcers the activation of specific neural pathways in the CNS that are the substrate of their motivational properties. Dopamine is recognized as the transmitter of one such neural pathway, being involved in at least three major aspects of motivation: modulation of motivational state, acquisition (incentive learning) and expression of incentive properties by motivational stimuli. Drugs of abuse of different pharmacological classes stimulate in the low dose range dopamine transmission particularly in the ventral striatum. Apart from psychostimulants, the evidence that stimulation of dopamine transmission by drugs of abuse provides the primary motivational stimulus for drug self-administration is either unconvincing or negative. However, stimulation of dopamine transmission is essential for the activational properties of drugs of abuse and might be instrumental for the acquisition of responding to drug-related incentive stimuli (incentive learning). Dopamine is involved in the induction and in the expression of behavioural sensitization by repeated exposure to various drugs of abuse. Sensitization to the dopamine-stimulant properties of specific drug classes leading to facilitation of incentive learning of drug-related stimuli might account for the strong control over behaviour exerted by these stimuli in the addiction state. Withdrawal from drugs of abuse results in a reduction in basal dopamine transmission in vivo and in reduced responding for conventional reinforcers. Although these changes are likely to be the expression of a state of dependence of the dopamine system their contribution to the motivational state of drug addiction is unclear.
滥用药物与传统强化物一样，会激活中枢神经系统中的特定神经通路，这些通路是其动机特性的基础。多巴胺被认为是其中一条神经通路的递质，至少参与动机的三个主要方面：动机状态的调节、习得（诱因学习）以及动机刺激的诱因特性的表达。不同药理类别的滥用药物在低剂量范围内会刺激多巴胺传递，尤其是在腹侧纹状体。除了精神兴奋剂外，滥用药物刺激多巴胺传递为药物自我给药提供主要动机刺激的证据要么缺乏说服力，要么是否定的。然而，多巴胺传递的刺激对于滥用药物的激活特性至关重要，并且可能有助于对与药物相关的诱因刺激做出反应的习得（诱因学习）。多巴胺参与了通过反复接触各种滥用药物而导致的行为敏化的诱导和表达。对特定药物类别的多巴胺刺激特性的敏化导致对与药物相关刺激的诱因学习的促进，这可能解释了这些刺激在成瘾状态下对行为的强大控制。停用滥用药物会导致体内基础多巴胺传递减少，以及对传统强化物的反应减少。尽管这些变化可能是多巴胺系统依赖状态的表现，但其对药物成瘾动机状态的贡献尚不清楚。
