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: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=716043
• 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发挥着关键作用。虽然DA从神经元神经末梢的释放是通过一种受调节的胞吐作用发生的，但DA也从DA神经元的细胞体和树突释放(STD DA释放)，对这种情况如何发生以及它在脑功能中扮演什么角色知之甚少。这项4年前启动的综合研究计划可能会使人们更好地理解DA神经元的作用。它还将描述一种机制，这将有助于解释树枝状释放其他化学信使，如5-羟色胺。也缺乏工具来检测DA神经元的躯体树突活动对腹侧中脑(这些神经元所在的位置)中存在的多种神经递质的动态影响。在这笔赠款的最后一期，我们已经开始开发新的动物模型，以更好地表征STD DA的释放并探索其机制。在与一位化学家同事的合作下，我们还建立了一种名为光学生理学的新方法来检查神经递质的动力学。开发更好的工具和更好的小鼠模型来干扰STD DA的释放将代表着该领域的重大进展，并可能导致更好地理解DA神经元的功能和可塑性的作用。我们将实现以下两个目标： 目的#1：确定STD DA释放的机制和作用。我们将检测STD DA在小鼠脑切片中的释放特性，在小鼠的脑切片中，突触素(Syts)是胞吐作用的关键钙触发器，在这些蛋白质中，突触素(Syts)被基因敲除。我们将特别研究syt4和syt7的作用，我们发现它们存在于DA神经元的STD区，以及syt1，只存在于轴突终末。我们假设，syt4和syt7的单个组成性KO将允许补偿，只有双KO导致STD DA释放受损。我们进一步假设，有条件地消融DA神经元的syt1将产生DA神经元仅从其STD隔室释放DA的小鼠。 目的#2：发展和使用光生理学来表征腹侧中脑神经递质对多巴胺能神经元STD活动的反应。我们与一位化学家同事合作开发了一种新的方法，可以基于定制设计的金纳米颗粒镀膜电极和表面增强拉曼光谱对神经递质进行多重检测。我们建议进一步发展这种“光生理学”技术，并将其优化用于脑片和完整动物的工作，以表征DA神经元的放电和DA的STD释放如何影响腹侧中脑中多神经递质的动力学。我们将检验STD DA释放调节神经递质分泌的假设，这些神经递质是从表达DAD1和D2受体的终末释放的。