Yager Lindsay M, Pitchers Kyle K, Flagel Shelly B, Robinson Terry E
Department of Psychology (Biopsychology Program), University of Michigan, Ann Arbor, MI, USA.
1] Department of Psychology (Biopsychology Program), University of Michigan, Ann Arbor, MI, USA [2] Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA [3] Molecular and Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, MI, USA.
Neuropsychopharmacology. 2015 Mar 13;40(5):1269-77. doi: 10.1038/npp.2014.314.
A discrete cue associated with intravenous injections of cocaine acquires greater control over motivated behavior in some rats ('sign-trackers', STs) than others ('goal-trackers', GTs). It is not known, however, if such variation generalizes to cues associated with other drugs. We asked, therefore, whether a discrete cue (a light) associated with the intravenous administration of an opioid drug (the short-acting mu receptor agonist, remifentanil) acquires incentive motivational properties differently in STs and GTs, as indicated by tests of Pavlovian conditioned approach and conditioned reinforcement. Consistent with studies using cocaine, STs approached a classically conditioned opioid cue more readily than GTs, and in a test of conditioned reinforcement worked more avidly to get it. Interestingly, STs and GTs did not differ in the acquisition of a conditioned orienting response. In addition, the performance of conditioned approach behavior, but not conditioned orientation, was attenuated by pretreatment with the dopamine receptor antagonist, flupenthixol, into the core of the nucleus accumbens. Lastly, food and opioid cues engaged similar amygdalo-striatal-thalamic circuitry to a much greater extent in STs than GTs, as indicated by Fos expression. Taken together, these data demonstrate that, similar to food and cocaine cues: (1) a discrete opioid cue attains greater incentive motivational value in STs than GTs; (2) the attribution of incentive motivational properties to an opioid cue is dopamine dependent; and (3) an opioid cue engages the so-called 'motive circuit' only if it is imbued with incentive salience.
与静脉注射可卡因相关的离散线索在一些大鼠（“信号追踪者”，STs）中比其他大鼠（“目标追踪者”，GTs）对动机行为具有更强的控制作用。然而，尚不清楚这种差异是否适用于与其他药物相关的线索。因此，我们研究了与静脉注射阿片类药物（短效μ受体激动剂瑞芬太尼）相关的离散线索（灯光）在STs和GTs中是否具有不同的激励动机特性，这通过巴甫洛夫条件性接近和条件性强化测试来表明。与使用可卡因的研究一致，STs比GTs更易接近经典条件化的阿片类线索，并且在条件性强化测试中更积极地努力获取它。有趣的是，STs和GTs在获得条件性定向反应方面没有差异。此外，向伏隔核核心注射多巴胺受体拮抗剂氟哌噻吨预处理会减弱条件性接近行为的表现，但不会减弱条件性定向的表现。最后，如Fos表达所示，食物和阿片类线索在STs中比在GTs中更大程度地激活了类似的杏仁核-纹状体-丘脑神经回路。综上所述，这些数据表明，与食物和可卡因线索类似：（1）离散的阿片类线索在STs中比在GTs中具有更大的激励动机价值；（2）阿片类线索激励动机特性的归因依赖于多巴胺；（3）阿片类线索只有在具有激励显著性时才会激活所谓的“动机回路”。
