Laurent Vincent, Wong Felix L, Balleine Bernard W
Behavioural Neuroscience Laboratory, Brain and Mind Research Institute, The University of Sydney, Camperdown, NSW, 2006, Australia.
Br J Pharmacol. 2015 Jan;172(2):562-70. doi: 10.1111/bph.12731. Epub 2014 Jul 1.
Stimuli that predict rewarding events can control choice between future actions, and this control could be mediated by δ-opioid receptors in the nucleus accumbens shell (NAc-S). Stimuli predicting the absence of important events can also guide choice, although it remains unknown whether they do so via changes in an accumbal δ-opioid receptor-related process.
δ-opioid receptor-eGFP mice were trained to perform two instrumental actions that delivered different food outcomes. Choice between the two actions was then tested in the presence of stimuli paired with either the delivery or the non-delivery of each of the two outcomes. Bilateral infusions of the δ-opioid receptor antagonist naltrindole into the NAc-S were used to determine the role of these receptors at the time of choice and δ-opioid receptor expression in the NAc-S used to assess functional activity.
A stimulus predicting a specific outcome biased choice performance towards the action previously earning that same outcome. In contrast, a stimulus signalling the absence of that outcome biased performance away from the action that delivered that outcome towards actions associated with the absence of that outcome. Both effects were associated with increased δ-opioid receptor expression on the membrane of cholinergic interneurons within the NAc-S. Furthermore, both effects were blocked by naltrindole infused into the NAc-S.
These findings suggest that δ-opioid receptors in the NAc-S were involved in the effects of predictive learning on choice between actions, whether those predictions involve the presence or absence of specific rewarding events.
This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2.
预测奖励事件的刺激能够控制未来行动之间的选择，并且这种控制可能由伏隔核壳（NAc-S）中的δ-阿片受体介导。预测重要事件缺失的刺激也能够指导选择，尽管它们是否通过伏隔核中与δ-阿片受体相关的过程变化来实现这一点仍不明确。
训练δ-阿片受体-eGFP小鼠执行两种可带来不同食物结果的操作性行为。然后在存在与两种结果之一的给予或不给予配对的刺激的情况下，测试这两种行为之间的选择。将δ-阿片受体拮抗剂纳曲吲哚双侧注入NAc-S，以确定这些受体在选择时的作用，并利用NAc-S中δ-阿片受体的表达来评估功能活性。
预测特定结果的刺激使选择表现偏向于先前获得相同结果的行为。相反，表明该结果缺失的刺激使表现偏离带来该结果的行为，转向与该结果缺失相关的行为。这两种效应均与NAc-S内胆碱能中间神经元膜上δ-阿片受体表达增加有关。此外，注入NAc-S的纳曲吲哚阻断了这两种效应。
这些发现表明，NAc-S中的δ-阿片受体参与了预测性学习对行为选择的影响，无论这些预测涉及特定奖励事件的存在还是缺失。
本文是关于阿片类药物：功能选择性新途径的主题部分的一部分。要查看本部分的其他文章，请访问http://dx.doi.org/10.1111/bph.2015.172.issue-2。
