Enhanced responding for conditioned reward produced by intra-accumbens amphetamine is potentiated after cocaine sensitization
Enhanced responding for conditioned reward produced by intra-accumbens amphetamine is potentiated after cocaine sensitization
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DOI：
10.1007/s002130050859
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发表时间：
1999-02-01
影响因子：
3.4
通讯作者：
Horger, BA
中科院分区：
文献类型：
--
作者：
Taylor, JR;Horger, BA
中脑边缘多巴胺（DA）系统与条件奖励（CR）、运动敏化和精神运动兴奋剂的强化特性有关。具有先前动机中性特性的刺激，通过与初级强化物的预测关联而获得激励特性，被称为条件强化物或二级强化物。在这些实验中，我们研究了可卡因致敏是否可以增强伏隔核内安非他明产生的CR的增强反应。受试者接受了14天的CR模式训练后，接受了可卡因增敏或生理盐水注射方案。在8-10天后的2个测试天，受试者分别向伏隔核（NAc）注入安非他明（6 μ g/0.5 μ l）或生理盐水，采用“获得新反应”模式测量CR反应。在一个新杠杆上的反应导致条件刺激的传递（条件强化物，或CR杠杆），而在另一个杠杆上的反应导致没有条件刺激的呈现（NCR杠杆）。对可卡因敏感的动物在nac生理盐水后CR水平反应增加，在nac安非他明后CR水平反应增强。在挑战后，可卡因组和盐水组在NCR水平上的反应没有差异。在这些条件下的运动致敏在另一组受试者中得到证实。这些发现表明，先前暴露于可卡因会导致改变，从而增强nac内安非他明增强CR的能力。重复使用兴奋剂药物可能会诱导长期的神经元适应，从而增加对兴奋剂药物的行为或激励动机效应的敏感性。
The mesolimbic dopamine (DA) system has been implicated in conditioned reward (CR), locomotor sensitization, and the reinforcing properties of psychomotor stimulants. Stimuli with formerly motivationally neutral properties that gain incentive properties by their predictive association with primary reinforcers are termed conditioned, or secondary, reinforcers. In these experiments, we investigated whether cocaine sensitization could potentiate augmented responding for CR produced by intra-accumbens amphetamine. After subjects were trained on the CR paradigm for 14 days, they received a regimen of cocaine sensitization or saline injections. On 2 test days, 8-10 days later, subjects were given amphetamine (6 mu g/0.5 mu l) or saline infusions into the nucleus accumbens (NAc) and responding for CR was measured using the "acquisition of a new response" paradigm. Responding on one novel lever resulted in the delivery of the conditioned stimulus (conditioned reinforcer, or CR lever), whereas responding on the other lever resulted in no CR stimulus presentation (NCR lever). Animals sensitized to cocaine showed increased responding on the CR lever after intra-NAc saline and potentiated CR lever responding after intra-NAc amphetamine. No differences in responding between the cocaine- and saline-treated groups on the NCR lever after the challenge were found. Locomotor sensitization under these conditions was confirmed in a separate group of subjects. These findings show that prior exposures to cocaine results in changes that potentiate the ability of intra-NAc amphetamine to enhance CR. Repeated stimulant drug use may induce long-term neuronal adaptations that result in increased sensitivity to the behavioral, or incentive motivational, effects of stimulant drugs.