MECHANISMS AND FUNCTIONS OF DENDRITIC DOPAMINE RELEASE IN THE BRAIN

大脑树突状多巴胺释放的机制和功能

• 批准号: RGPIN-2020-05279
• 负责人: Trudeau, LouisEric
• 金额: $ 4.23万
• 依托单位: Université de Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=762058
• 关键词: MECHANISMS; FUNCTIONS; DENDRITIC; DOPAMINE; RELEASE

Neurons in the brain that use the chemical messenger dopamine (DA) play a key role in the control of movement, motivated behaviors and cognition. Although DA release from the neurons' nerve endings occurs through a form of regulated exocytosis, DA is also released from the cell body and dendrites of DA neurons (STD DA release) and very little is known about how this occurs and what roles it plays in brain function. This integrated research program, initiated 4 years ago, may lead to a better understanding of the roles of DA neurons. It will also characterize a mechanism that will help explain the dendritic release of other chemical messengers such as 5-HT. There is also a paucity of tools to detect the impact of the somatodendritic activity of DA neurons on the dynamics of the multiple neurotransmitters present in the ventral midbrain, where these neurons are located. During the last term of this grant, we have begun to develop new animal models to better characterize STD DA release and explore its mechanisms. In collaboration with a chemist colleague, we also established a new approach called optophysiology to examine neurotransmitter dynamics. The development of better tools and better mouse models in which STD DA release is perturbed will represent a major advance in the field and may lead to a better comprehension of the roles of functional and plasticity of DA neurons. We will address the following two aims: Aim #1: Identification of the mechanisms and roles of STD DA release. We will examine the properties of STD DA release in brain sections prepared from mice in which synaptotagmins (syts), proteins that are key calcium triggers of exocytosis, are genetically knocked out. We will examine in particular the roles of syt4 and syt7, which we have found to be present in the STD compartment of DA neurons, as well as syt1, present only in axon terminals. We hypothesize that individual constitutive KO of syt4 and syt7 will allow compensation, with only the double KO leading to impaired STD DA release. We further hypothesize that conditional ablation of syt1 from DA neurons will generate mice in which DA neurons only release DA from their STD compartment. Aim #2: Development and use of optophysiology to characterize neurotransmitter dynamics in the ventral midbrain in response to STD activity of DA neurons. We have teamed up with a chemist colleague to develop a novel approach allowing multiplex detection of neurotransmitters based on custom-designed gold nanoparticle-plated electrodes and surface-enhanced Raman spectroscopy. We propose to further develop this "optophysiology" technique and optimize it for work in brain slices and intact animals, to characterize how the firing of DA neurons and the STD release of DA affects the dynamics of multiple neurotransmitters in the ventral midbrain. We will test the hypothesis that STD DA release regulates the secretion of neurotransmitters that are released from terminals expressing DA D1 and D2 receptors.

大脑中使用化学信使多巴胺（DA）的神经元在控制运动，动机行为和认知方面起着关键作用。虽然DA从神经元的神经末梢的释放是通过一种受调节的胞吐作用的形式发生的，但DA也从DA神经元的细胞体和树突释放（STD DA释放），并且很少有人知道这是如何发生的以及它在脑功能中扮演什么角色。这项4年前启动的综合研究计划可能会更好地了解DA神经元的作用。它还将描述一种机制，这将有助于解释树突释放其他化学信使，如5-HT。也有一个缺乏的工具来检测DA神经元的体树突活动的动态的多种神经递质存在于腹侧中脑，这些神经元所在的影响。在该资助的最后一个学期，我们已经开始开发新的动物模型，以更好地表征STD DA释放并探索其机制。在与一位化学家同事的合作中，我们还建立了一种称为视生理学的新方法来检查神经递质动力学。开发更好的工具和更好的小鼠模型，其中STD DA释放受到干扰，将代表该领域的重大进展，并可能导致更好地理解DA神经元的功能和可塑性的作用。我们将解决以下两个目标：目标#1：确定STD DA释放的机制和作用。我们将研究从小鼠制备的脑切片中STD DA释放的特性，其中突触结合蛋白（syts）是胞吐作用的关键钙触发剂，被基因敲除。我们将特别研究syt 4和syt 7的作用，我们发现它们存在于DA神经元的STD隔室中，以及syt 1，只存在于轴突末梢中。我们假设syt 4和syt 7的个体组成性KO将允许补偿，只有双KO导致受损的STD DA释放。我们进一步假设，条件性消融多巴胺神经元的syt 1将产生小鼠，其中DA神经元只释放DA从他们的STD室。目标二：开发和使用视生理学来表征腹侧中脑中响应DA神经元STD活动的神经递质动力学。我们与一位化学家同事合作开发了一种新方法，该方法允许基于定制设计的镀金纳米颗粒电极和表面增强拉曼光谱对神经递质进行多重检测。我们建议进一步开发这种“视生理学”技术，并优化它的工作在脑切片和完整的动物，以表征如何发射DA神经元和STD释放DA影响多种神经递质的动力学在腹侧中脑。我们将测试的假设，STD DA释放调节神经递质的分泌，从终端表达DA D1和D2受体。