Mouse Models of Habenula Development and Function in Mental Illness and Addiction

精神疾病和成瘾中缰核发育和功能的小鼠模型

• 批准号: 7875023
• 负责人: Eric E. Turner
• 金额: $ 24.38万
• 依托单位: SEATTLE CHILDREN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-04-15 至 2012-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7875023
• 关键词: Acetylcholine; Action Potentials; Address; Adult; Area; Attention; Behavior; Behavioral; Brain; Cell Nucleus; Cells; Characteristics; Chloride Ion; Chlorides; Cholinergic Receptors; Complex; Defect; Development; Disease; Dopamine; Dorsal; Drug Addiction; Epithalamic structure; Exhibits; Fiber; Fiber Optics; Fluorescence; Frequencies; Functional disorder; Future; Gene Expression; Genes; Genetic; Glutamates; Goals; Habenula; Halorhodopsins; Human; Implant; Injection of therapeutic agent; Knockout Mice; Lateral; Learning; Lesion; Light; Location; Mammals; Medial; Mediating; Memory; Mental disorders; Methods; Midbrain structure; Modeling; Molecular; Motivation; Movement; Mus; Neurons; Nicotine; Nicotine Dependence; Output; Pathway interactions; Pattern; Play; Positioning Attribute; Preparation; Process; Property; Prosencephalon; Proteins; Pump; Punishment; Reporter; Reproductive Behavior; Research; Rewards; Role; Schizophrenia; Serotonin; Sleep Wake Cycle; Slice; System; Tegmentum Mesencephali; Testing; Thalamic structure; Toxin; Transgenic Mice; Work; addiction; basal forebrain; base; biological adaptation to stress; cholinergic; diphtheria toxin receptor; drug development; drug of abuse; feeding; homeodomain; innovation; interpeduncular nucleus; microbial; mouse model; nerve supply; neural circuit; nicotine abuse; public health relevance; recombinase; research study; reward processing; tool; transcription factor

DESCRIPTION (provided by applicant): This is an exploratory R21 proposal focused on the development and function of the medial habenula. The habenula is a paired nucleus residing in the dorsal thalamus (epithalamus). It consists of lateral and medial subnuclei which participate in largely distinct neural circuits. Both parts of the habenula send their output fibers to the ventral midbrain via the prominent habenulopeduncular tract or fasciculus retroflexus (FR). The lateral habenula directly innervates the midbrain dopamine and serotonin systems, while the medial habenula sends a prominent cholinergic projection to the interpeduncular nucleus, which in turn innervates the ventral midbrain. In recent work we have shown that the habenula has a pattern of gene expression quite distinct from other forebrain or thalamic areas, and that a homeodomain transcription factor, Brn3a (pou4f1), regulates many of the characteristic molecular features of the medial habenula and a subset of lateral habenula neurons. Little is known about the function of the medial habenula, but its position at the interface between the limbic/basal forebrain and midbrain monoaminergic systems suggests role in reward, attention, learning and drug dependence. For this reason it has been hypothesized that habenular dysfunction may play a role in schizophrenia, and that drug development for nicotine abuse should be targeted to the habenular pathway. Aim 1 will use genetic methods to disrupt the habenulopeduncular pathway by targeted deletion of Brn3a, using expression of Cre recombinase from the Nurr1 (nr4a2) gene locus. We will test the specific hypothesis that the developmental defects in the habenular projections observed in Brn3a knockout mice are due to a cell-autonomous requirement for Brn3a. Aim 2 will use a mixed-genetic/stereotactic injection strategy to specifically ablate the cholinergic component of the medial habenula in adult mice, based on the targeted expression of inducible diphtheria toxin receptor (iDTR). We will test the hypothesis that such lesions will result in a complete loss of cholinergic and glutamatergic innervation of the central IPN by the habenula, while peptidergic innervation of the lateral IPN will be spared. Aim 3 will develop transgenic mice permitting the light inducible, reversible inhibition of habenula activity using targeted expression of the light-activated chloride pump halorhodopsin, fused to a YFP reporter. We will use YFP fluorescence to identify habenula neurons in slice preparations, and test the hypothesis that Brn3a+ neurons exhibit the low-frequency spontaneous depolarizations previously described in the habenula. We will determine whether this activity and induced action potentials can be inhibited by light. Beyond the specific aims of the proposal, these experiments will generate mouse models to be used in future R01 proposals examining the role of complex behaviors related to schizophrenia and nicotine abuse. PUBLIC HEALTH RELEVANCE: The habenula is brain nucleus in the dorsal thalamus of all mammals that connects the forebrain to midbrain centers associated with motivation, reward, attention, and movement. Despite its central location, remarkably little is known about the function of this nucleus. The present proposal will create transgenic mice in which: 1) the habenula is developmentally disconnected from its targets, or 2) genetically defined medial habenula neurons can be selectively ablated by the injection of a toxin, or 3) habenula function can be turned off with light from an implanted fiber optic probe. These mice will be used to address specific questions about how the habenula develops its unique properties, and in future experiments to determine habenula function in memory, learning, attention, and models of schizophrenia and nicotine dependence.

描述（由申请方提供）：这是一项探索性R21提案，重点关注内侧缰核的发育和功能。缰核是位于背侧丘脑（上丘脑）的成对核团。它由外侧亚核和内侧亚核组成，它们参与很大程度上不同的神经回路。缰核的这两个部分通过突出的缰脚束或反曲束（FR）将其输出纤维发送到腹侧中脑。外侧缰直接支配中脑多巴胺和5-羟色胺系统，而内侧缰向脚间核发送突出的胆碱能投射，脚间核又支配中脑腹侧。在最近的工作中，我们已经表明，缰有一个模式的基因表达完全不同于其他前脑或丘脑地区，和同源结构域转录因子，Brn 3a（pou 4f 1），调节许多特征性的内侧缰和外侧缰神经元的一个子集的分子特征。关于内侧缰核的功能知之甚少，但其在边缘系统/基底前脑和中脑单胺能系统之间的界面上的位置表明其在奖励，注意力，学习和药物依赖中的作用。因此，有人假设缰核功能障碍可能在精神分裂症中起作用，尼古丁滥用药物的开发应针对缰核通路。 目的1将使用遗传学方法，通过靶向缺失Brn 3a，使用来自Nurr 1（nr 4a 2）基因位点的Cre重组酶的表达来破坏缰脚途径。我们将测试特定的假设，即在Brn 3a基因敲除小鼠中观察到的缰突起的发育缺陷是由于Brn 3a的细胞自主需求。 目的2基于诱导型白喉毒素受体（inducible diphtheria toxin receptor，iDTR）的靶向表达，采用混合遗传/立体定向注射策略，特异性切除成年小鼠内侧缰核的胆碱能成分。我们将测试的假设，这样的病变将导致在一个完全丧失的胆碱能和hematergic神经支配的中央IPN的缰，而肽能神经支配的侧IPN将幸免。 目的3将开发转基因小鼠，允许光诱导的，可逆的抑制缰活性使用光激活的氯泵盐视紫红质，融合到YFP报告基因的靶向表达。我们将使用YFP荧光识别缰神经元切片制备，并测试的假设，Brn 3a+神经元表现出低频自发去极化先前描述的缰。我们将确定这种活动和诱导的动作电位是否可以被光抑制。 除了提案的具体目标之外，这些实验还将产生小鼠模型，用于未来的R 01提案，研究与精神分裂症和尼古丁滥用相关的复杂行为的作用。 公共卫生关系：缰核是所有哺乳动物背侧丘脑的脑核，连接前脑和中脑中心，与动机、奖励、注意力和运动有关。尽管它位于中心位置，但人们对这个核的功能知之甚少。目前的提议将创建转基因小鼠，其中：1）缰核与其目标在发育上断开，或2）遗传上确定的内侧缰核神经元可以通过注射毒素选择性地消融，或3）缰核功能可以通过来自植入的光纤探针的光关闭。这些小鼠将用于解决有关缰如何发展其独特特性的具体问题，并在未来的实验中确定缰在记忆，学习，注意力以及精神分裂症和尼古丁依赖模型中的功能。