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: 10217838
• 负责人: Susana Passos Mingote
• 金额: $ 23.55万
• 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/10217838
• 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 多种脑疾病的认知缺陷与皮质中的多巴胺（DA）水平改变有关 皮质活动异常，并对我们的社会产生深远的情感和经济影响。成像和 验尸研究表明，皮质DA合成的总体下降并释放为潜在 脑部疾病的病理学。但是，由于我们对正常连接性的了解有限，因此 具有挑战性的是建立DA级别的变化与神经元电路的变化之间的联系，这将 显着提高了我们对皮质功能障碍的机械理解。进度受到限制 皮质中DA神经元突触作用的复杂性，涉及谷氨酸（GLU）的共释放。 中脑DA-GLU神经元在通过快速GLU介导的增加神经元触发的能力上是独一无二的 信号和影响皮层活动，但尚不知道这些神经元的功能如何受到 低多巴胺能。在这里，我们将通过在小鼠中调查分子，突触和 DA-GLU共同释放的神经元中降低DA合成的电路效应，这些神经元投射到皮质上。这些 关键发现将指导未来行为研究的选择。由于da neuron glu共转移是 通过系统发育保存并在人类中发现，我们的研究将提供新的机械见解 DA失调对皮质功能障碍的影响。 据报道，在 下丘脑DA-GLU神经元导致谷氨酸转运蛋白2（VGLUT2）， 表明GLU释放增加。投射到皮层的DA-GLU神经元使得优先连接 外侧内肾上腺皮质（LEC）中的锥体输出神经元和前额叶的GABA中间神经元 皮质（PFC）。我们的假设是，当DA合成降低时，LEC和PFC-PRODING 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。这个神经递质 从DA-GLU到仅GLU的开关将差异地影响LEC和PFC输出神经元的活性。我们 预测，在低载胺能力下，DA-GLU神经元的触发将显着增加LEC输出 由于加强与锥体神经元的连接而导致的活性，同时显着降低了PFC输出 由于加强与抑制PFC输出神经元的GABA能中间神经元的连接而导致的活性。到 检验这一假设，我们将在TH-lox的小鼠中使用截切面病毒策略来从遗传性无效TH LEC和PFC射击神经元。然后，我们将确定这种操作是否有助于GLU共同 通过在AIM 1中上调在转录本和蛋白水平上的VGLUT2表达来传播；和 去除DA介导的GLU共递传介导的抑制作用并增加DA-GLU神经元 使用离体突触生理学和体内钙成像对AIM 2中皮质活性的控制。