Neural substrates of elevated striatal dopamine synthesis and release in schizophrenia

精神分裂症纹状体多巴胺合成和释放升高的神经基质

• 批准号: 10409842
• 负责人: JILL RENEE' Glausier
• 金额: $ 19.85万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-06-01 至 2024-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10409842
• 关键词: Affect; Anatomy; Antipsychotic Agents; Autopsy; Axon; Back; Biological Models; Brain; Characteristics; Choline O-Acetyltransferase; Chronic; Clinical; Confocal Microscopy; Corpus striatum structure; Data; Development; Disease; Dopamine; Dopamine D2 Receptor; Dorsal; Drug Exposure; Electron Microscopy; Electrons; Enzymes; Exhibits; Exposure to; Foundations; Functional disorder; Future; Human; Immunofluorescence Microscopy; Individual; Interneurons; Label; Measures; Midbrain structure; Molecular; Monkeys; Nicotinic Receptors; Onset of illness; Proteins; Psychiatry; Psychoses; Psychotic Disorders; Resolution; Role; Schizophrenia; Signal Transduction; Site; Specificity; Synapses; Testing; Therapeutic Effect; Transferase; Transmission Electron Microscopy; Tyrosine 3-Monooxygenase; Vesicle; atypical antipsychotic; brain tissue; cholinergic; cohort; density; design; dopamine transporter; dopaminergic neuron; evidence base; in vivo; neural circuit; neuroimaging; novel; postsynaptic; presynaptic; relating to nervous system; reuptake; transmission process; vesicular monoamine transporter 2; vesicular release

7. PROJECT SUMMARY/ABSTRACT Psychosis is a core clinical feature of schizophrenia (SZ) associated with elevated dopamine (DA) synthesis and release in the associative striatum (AST), but not the limbic striatum (LST). Determining the molecular and subcellular substrates of this region-specific presynaptic pathophysiology of psychosis in the disease state requires studies at the site of DA release, DA axonal boutons. This level of resolution in humans can only be achieved in postmortem brain studies. Elevated presynaptic DA signaling in the AST in SZ could be due to molecular changes within DA boutons. Specifically, greater protein levels of tyrosine hydroxylase (TH), vesicular monoamine transporter 2 (VMAT2) or the DA transporter (DAT), which govern DA synthesis, packaging for vesicular release and reuptake into the bouton, respectively, could represent molecular substrates of this pathophysiology. These molecular changes would be accompanied by ultrastructural alterations reflecting greater DA vesicular release. Alternately, or additionally, a greater density of DA boutons could be the substrate for elevated presynaptic DA signaling. Thus, in Aim 1 we test each of these possibilities by using triple-label immunofluorescence and confocal microscopy in SZ and unaffected comparison (CON) subjects to simultaneously quantify the abundance of TH, VMAT2 and DAT within DA boutons and the density of DA boutons in the AST and LST (Exp 1.1), and DA vesicle density is quantified via serial section transmission electron microscopy (Exp 1.2). Studies are repeated in monkeys chronically exposed to antipsychotic drugs (Exp 1.3). The findings in Aim 1 may result from alterations to local striatal cholinergic interneurons (ChIs) that affect DA boutons. Indeed, because markers of presynaptic DA signaling are normally greater in the AST than LST, an exaggeration of the factors that contribute to this regional specificity might underlie the AST-specific finding in SZ. ChIs are a compelling candidate as they exhibit greater functional and anatomical measures in the AST than LST and potently regulate DA synthesis and release by providing direct axo-axonic inputs to DA boutons. Activation of nicotinic acetylcholine receptors containing the β2 subunit (nAChRβ2) located on DA boutons induces DA release independent of DA neuron firing in the midbrain. Measures reflecting elevated presynaptic DA signaling in the AST in SZ might be the consequence of a greater proportion of DA boutons receiving ChI inputs and/or higher levels of molecular determinants of ChI synaptic strength, such as levels of ACh transferase (ChAT) and/or nAChRβ2. Thus, in Aim 2 we utilize quadruple-label immunofluorescence and confocal microscopy to simultaneously quantify the proportion of DA boutons receiving a ChI axo-axonic input and the abundance of ChAT and nAChRβ2 at these inputs in the AST and LST. As in Aim 1, studies are repeated in monkeys chronically exposed to antipsychotic drugs. These subcellular, molecular and ultrastructural analyses will provide the first comprehensive, region-specific analysis of the neural substrates and upstream factors of elevated presynaptic DA signaling in the AST of SZ and form the foundation of a future R01 application.

7.项目总结/摘要 精神病是精神分裂症（SZ）的核心临床特征，与多巴胺（DA）合成升高相关， 在联合纹状体（AST）中释放，但不在边缘纹状体（LST）中释放。确定分子和 亚细胞基质的这一区域特异性突触前病理生理的精神病在疾病状态 需要在DA释放的部位进行研究，DA轴突终扣。人类的这种分辨率只能是 在死后的大脑研究中取得的。SZ中AST中突触前DA信号的升高可能是由于 DA终扣内的分子变化。具体而言，酪氨酸羟化酶（TH）、囊泡 单胺转运蛋白2（VMAT 2）或DA转运蛋白（DAT），其控制DA合成，包装用于 囊泡释放和再摄取到bouton，分别可以代表这一分子底物， 病理生理学这些分子变化将伴随着超微结构的改变， 更大的DA囊泡释放。替代地或另外地，更大密度的DA纽扣可以是基底 突触前多巴胺信号的升高因此，在目标1中，我们通过使用三重标签来测试这些可能性中的每一个 SZ和未受影响的比较（CON）受试者的免疫荧光和共聚焦显微镜检查， 同时定量DA终扣内TH、VMAT 2和DAT的丰度以及DA终扣的密度 在AST和LST中（实验1.1），通过连续切片透射电子显微镜定量DA囊泡密度 显微镜检查（实验1.2）。在长期暴露于抗精神病药物的猴中重复研究（实验1.3）。 目的1中的发现可能是由于影响DA的局部纹状体胆碱能中间神经元（ChIs）的改变 饰扣事实上，由于突触前DA信号的标记物在AST中通常比LST中更大， 夸大导致这种区域特异性的因素可能是AST特异性发现的基础， SZ. ChI是一个令人信服的候选者，因为它们在AST中表现出比 LST通过向DA终扣提供直接的轴突-轴突输入而有效地调节DA的合成和释放。 DA终扣上含β2亚单位的烟碱乙酰胆碱受体（nAChRβ2）的激活 诱导DA释放，而不依赖于中脑中DA神经元的放电。反映突触前升高的措施 SZ的AST中的DA信号可能是更大比例的DA终扣接受ChI的结果 输入和/或ChI突触强度的更高水平的分子决定因素，如ACh转移酶水平 （ChAT）和/或nAChRβ2。因此，在目标2中，我们利用四重标记免疫荧光和共聚焦显微镜。 显微镜下同时定量接受ChI轴突-轴突输入的DA终扣的比例， AST和LST中这些输入处的ChAT和nAChRβ2丰度。与目标1一样， 长期接触抗精神病药物的猴子。这些亚细胞分子和超微结构分析 将提供第一个全面的，区域特定的神经基板和上游因素的分析， SZ AST中突触前DA信号传导升高，并构成未来R 01应用的基础。