Effects of Decreased Dopamine Synthesis on Glutamate Co-Transmission and Cortical Activity

多巴胺合成减少对谷氨酸共同传递和皮质活动的影响

• 批准号: 10359172
• 负责人: Susana Passos Mingote
• 金额: $ 19.63万
• 依托单位: ADVANCED SCIENCE RESEARCH CENTER
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-03-01 至 2023-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10359172
• 关键词: Address; Affect; Autopsy; Behavior; Brain; Brain Diseases; Calcium; Cells; Cognitive deficits; Complex; Corpus striatum structure; Dopamine; Emotional; Enzymes; Fire - disasters; Functional disorder; Future; Genes; Glutamates; Human; Hypothalamic structure; Image; Immunofluorescence Immunologic; Interneurons; Knowledge; Lateral; Link; LoxP-flanked allele; Measures; Mediating; Microscopy; Midbrain structure; Molecular; Mus; Neurons; Neurotransmitters; Output; Pathology; Phylogeny; Physiology; Population; Prefrontal Cortex; Proteins; Reporting; Research; Resolution; Signal Transduction; Signaling Molecule; Slice; Societies; Synapses; Testing; Time; Transcript; Tyrosine 3-Monooxygenase; Up-Regulation; Ventral Tegmental Area; Viral; Whole-Cell Recordings; behavior test; behavioral study; cell type; dopaminergic neuron; entorhinal cortex; follow-up; gamma-Aminobutyric Acid; hippocampal pyramidal neuron; in vivo; in vivo calcium imaging; insight; molecular phenotype; neural circuit; neuronal circuitry; novel; preservation; response; transmission process; vesicular glutamate transporter 2

Project Summary Cognitive deficits in several brain disorders are associated with altered dopamine (DA) levels in the cortex and abnormal cortical activity, and have a profound emotional and financial impact in our society. Imaging and post-mortem studies point to an overall decrease in cortical DA synthesis and release as an underlying pathology in brain disorders. However, due to our limited knowledge of normal connectivity, it has been challenging to establish links between changes in DA levels and alterations in neuronal circuits, which would significantly advance our mechanistic understanding of cortical dysfunctions. Progress is limited by the complexity of DA neuron synaptic actions in the cortex that involve the co-release of glutamate (GLU). Midbrain DA-GLU neurons are unique in their ability to increase neuronal firing through fast GLU-mediated signals and influence cortical activity, but it is not known how the function of these neurons is affected by hypodopaminergia. Here we will address this question by investigating, in mice, the molecular, synaptic, and circuit effects of decreasing DA synthesis in DA-GLU co-releasing neurons projecting to the cortex. These critical findings will guide the selection of future behavioral studies. Since DA neuron GLU co-transmission is preserved through phylogeny and is found in humans, our research will provide novel mechanistic insights into the DA dysregulation effects on cortical dysfunctions. It has been reported that decreased tyrosine hydroxylase (TH) expression (a key enzyme in DA synthesis) in hypothalamic DA-GLU neurons results in upregulation of vesicular glutamate transporter 2 (VGLUT2), suggesting increased GLU release. DA-GLU neurons projecting to the cortex make preferential connections to pyramidal output neurons in the lateral entorhinal cortex (LEC) and to GABA interneurons in the prefrontal cortex (PFC). Our hypothesis is that, when DA synthesis is decreased, both LEC- and PFC-projecting DA-GLU neurons will increase their release of GLU and use it as their main signaling molecule. This neurotransmitter switch, from DA-GLU to GLU-only, will differentially affect the activity of the LEC and PFC output neurons. We predict that, under hypodopaminergia, the firing of DA-GLU neurons will significantly increase LEC output activity due to strengthening of connections to pyramidal neurons, while significantly decreasing PFC output activity due to the strengthening of connections to GABAergic interneurons that inhibit PFC output neurons. To test this hypothesis, we will use intersectional viral strategies in TH-floxed mice to genetically inactive TH from LEC- and PFC-projecting DA neurons. We will then determine if this manipulation facilitates GLU co- transmission, by upregulating VGLUT2 expression at the transcript and protein levels in Aim 1; and by removing inhibitory effects mediated by DA on GLU co-transmission and increasing the DA-GLU neuron control over cortical activity in Aim 2, using ex vivo synaptic physiology and in vivo calcium imaging.

项目摘要 几种脑部疾病的认知缺陷与皮质中多巴胺（DA）水平的改变有关， 异常的皮质活动，并对我们的社会产生深刻的情感和经济影响。成像和 死后研究指出，皮质DA合成和释放的总体减少是一种潜在的神经功能障碍， 大脑疾病的病理学然而，由于我们对正常连接的知识有限， 建立DA水平变化与神经元回路改变之间的联系具有挑战性， 大大推进了我们对大脑皮层功能障碍机制的理解。进展受到限制， 皮质中DA神经元突触活动的复杂性，涉及谷氨酸（GLU）的共同释放。 中脑DA-GLU神经元是独特的，它们能够通过快速GLU介导的增强神经元放电。 信号并影响皮层活动，但尚不清楚这些神经元的功能如何受到 多巴胺能不足在这里，我们将解决这个问题，通过调查，在小鼠，分子，突触， 在DA-GLU共释放神经元投射到皮层的减少DA合成的回路效应。这些 关键的发现将指导未来行为研究的选择。由于DA神经元GLU共传递是 通过遗传学保存下来，并在人类中发现，我们的研究将提供新的机制见解， DA调节异常对皮质功能障碍的影响。 有报道称，酪氨酸羟化酶（TH）表达降低（DA合成的关键酶）， 下丘脑DA-GLU神经元导致囊泡谷氨酸转运蛋白2（VGLUT 2）的上调， 表明GLU释放增加。投射到皮层的DA-GLU神经元优先连接到 外侧内嗅皮层（LEC）的锥体输出神经元和前额叶皮层的GABA中间神经元 皮质（PFC）。我们的假设是，当DA合成减少时，LEC和PFC投射的DA-GLU 神经元将增加其GLU的释放并将其用作其主要信号分子。这种神经递质 从DA-GLU到仅GLU的切换将不同地影响LEC和PFC输出神经元的活性。我们 预测，在多巴胺能不足的情况下，DA-GLU神经元的放电将显著增加LEC输出 活动由于加强连接锥体神经元，同时显着减少PFC输出 由于加强了与抑制PFC输出神经元的GABA能中间神经元的连接而导致的活动。到 为了验证这一假设，我们将在TH-floxed小鼠中使用交叉病毒策略， LEC和PFC投射DA神经元。然后，我们将确定这种操作是否有助于GLU共同- 通过在Aim 1中在转录物和蛋白质水平上上调VGLUT 2表达，以及通过在Aim 1中在转录物和蛋白质水平上上调VGLUT 2表达， 消除DA对GLU共传递的抑制作用，增加DA-GLU神经元 在Aim 2中，使用离体突触生理学和体内钙成像控制皮质活动。

项目成果

Role of Dopamine Neurons in Familiarity.

多巴胺神经元在熟悉度中的作用。

• DOI: 10.1101/2023.10.25.564006
• 发表时间: 2023
• 期刊: bioRxiv : the preprint server for biology
• 作者: Fleury,Sixtine;Kolaric,Rhonda;Espera,Justin;Ha,Quan;Tomaio,Jacquelyn;Gether,Ulrik;Sørensen,AndreasToft;Mingote,Susana
• 通讯作者: Mingote,Susana