Differential modulation of dopamine neurons by distinct neurotensin inputs

项目总结/摘要 已知肽神经降压素（NTS）是多巴胺神经元活性的有效调节剂，并且NTS 信号传递与行为强化和奖励的各种形式有关， 对药物滥用的行为反应和吸毒的动机。药理学研究发现 在腹侧被盖区（VTA），NTS与其受体结合，通过一种抑制多巴胺能神经元极化的机制， 各种第二信使级联反应，导致多巴胺神经元放电增加， 多巴胺释放然而，关于NTS从内源性神经递质中的生理释放， 大脑回路，以及这些回路在调节动机行为中可能发挥的作用。使用逆行标测 我们确定了23个向腹侧被盖区发送NTS输入的大脑区域;然而，这些输入中很少有被很好地研究， 它们在NTS信号传导中的作用，并且对什么刺激或行为动作可以激活NTS知之甚少 神经元此外，尽管肽能神经元通常共同释放快速神经递质，如 谷氨酸或GABA，目前的回路特异性激活方法无法区分下游 肽触发的效应与快速递质诱发的效应。我们假设不同的NTS 投射到腹侧被盖区可能在调节动机性行为中发挥不同的作用， 与共同释放的快速递质协同作用以控制下游多巴胺神经元的动力学 activation.在这里，我们建议确定选择NTS输入到VTA的神经递质共表达 并绘制它们与多巴胺和非多巴胺神经元的突触连接。我们还建议使用病毒 CRISPR基因诱变技术结合光遗传学分离多肽并快速 NTS输入到VTA的变送器组件。我们将分析这些成分在调节 行为强化的不同模式，并将测量体内多巴胺神经元对 刺激特定的输入。最后，我们将使用光纤光度法来测量NTS的活性分布 神经元在学习和执行提示恢复食物奖励任务。所有这些 实验将增加前所未有的电路特定的精度，我们的理解，这些关键的 肽能输入影响多巴胺神经元的活动状态，并控制奖赏和强化 学习

Project Summary/Abstract The peptide neurotensin (NTS) is known to be a potent modulator of dopamine neuron activity, and NTS signaling has been linked to various modalities of behavioral reinforcement and reward, as well as to the behavioral response to drugs of abuse and the motivation for drug taking. Pharmacological studies have found that in the ventral tegmental area (VTA), NTS binding to its receptors depolarizes dopamine neurons through a variety of second messenger cascades, resulting in increased dopamine neuron firing and downstream dopamine release. However, much less is known about the physiological release of NTS from endogenous brain circuits and what role these circuits may play in regulating motivated behavior. Using retrograde mapping we identified 23 brain regions that send NTS input to the VTA; however, few of these inputs are well-studied for their role in NTS signaling, and little is known about what stimuli or behavioral actions may activate NTS neurons. Furthermore, though peptidergic neurons typically co-release a fast neurotransmitter, such as glutamate or GABA, current methods for circuit-specific activation fail to distinguish between downstream effects triggered by peptides versus those evoked by fast transmitters. We hypothesize that different NTS projections to the VTA may play distinct roles in modulating motivated behavior, and that NTS acts synergistically with co-released fast transmitters to govern the dynamics of downstream dopamine neuron activation. Here we propose to determine the neurotransmitter co-expression of select NTS inputs to the VTA and map their synaptic connectivity to dopamine and non-dopamine neurons. We also propose to use viral CRISPR gene mutagenesis techniques in combination with optogenetics to isolate the peptide and fast transmitter components of NTS inputs to the VTA. We will dissect the role of these components in regulating different modalities of behavioral reinforcement and will measure the response of dopamine neurons in vivo to stimulation of specific inputs. Finally, we will use fiber photometry to measure the activity profiles of NTS neurons during learning and performance of a cued reinstatement food reward task. Together, these experiments will add unprecedented circuit-specific precision to our understanding of how these critical peptidergic inputs influence the activity state of dopamine neurons and govern reward and reinforcement learning.