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.项目摘要/摘要 精神病是精神分裂症(SZ)的核心临床特征，与多巴胺(DA)合成和 在联合纹状体(AST)释放，但不在边缘纹状体(LST)释放。确定分子和 疾病状态下精神病的该区域特异性突触前病理生理学的亚细胞底物 需要对DA释放部位--DA轴突进行研究。人类的这种分辨率水平只能是 在死后的大脑研究中取得的成就。SZ区AST区突触前DA信号升高可能是由于 DA Boutons内的分子变化。具体地说，酪氨酸羟化酶(TH)的蛋白质水平较高，囊泡 单胺转运体2(VMAT2)或DA转运体(DAT)，它管理DA的合成，包装 囊泡的释放和再摄取分别可以代表这一分子底物。 病理生理学。这些分子变化会伴随着超微结构的变化， 更大的DA囊泡释放。可替换地或另外地，更大密度的DA粒子可以是衬底 用于突触前DA信号的升高。因此，在目标1中，我们通过使用三重标记来测试这些可能性 SZ与正常对照(CON)患者的免疫荧光和共聚焦显微镜观察 同时量化DA核子内TH、VMAT2和DAT的丰度和密度 在AST和LST(Exp 1.1)中，DA囊泡密度通过连续切片传输电子来定量 显微镜(实验1.2)。在长期接触抗精神病药物的猴子身上重复研究(实验1.3)。 AIM 1中的发现可能是由于纹状体局部胆碱能中间神经元(CHI)的改变而影响DA 关于这一点。事实上，因为突触前DA信号的标志物通常在AST比LST更大，所以 对导致这种区域特异性的因素的夸大可能是AST特异性发现的基础 SZ.CHI是一个引人注目的候选者，因为它们在AST中表现出更大的功能和解剖指标 LST通过向DA神经元提供直接的轴突输入，有效地调节DA的合成和释放。 含β-2亚单位的烟碱型乙酰胆碱受体(β-2)的激活作用 在中脑诱导不依赖于DA神经元放电的DA释放。反映突触前升高的指标 深圳AST中的DA信号可能是更大比例的DA信号接收CHI的结果 CHI突触强度的输入和/或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，我们使用四标记免疫荧光和共聚焦 用显微镜同时量化接受CHI轴突输入的DA Bouton的比例 谷氨酸转氨酶和谷氨酸转运蛋白受体β-2在这些输入端均有丰富的表达。与目标1相同，研究重复于 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，区域特定的神经底物和上游因素的分析 突触前DA信号在SZ的AST中升高，为未来R01的应用奠定了基础。