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Mechanisms of Serotonin Axon Regeneration Revealed by In Vivo 2-photon Microscopy in the Mouse

小鼠体内 2 光子显微镜揭示的血清素轴突再生机制

基本信息

批准号：
8908695
负责人：
Sarah Dougherty
金额：
$ 5.42万
依托单位：
JOHNS HOPKINS UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2015
资助国家：
美国
起止时间：
2015-04-01 至 2018-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8908695
关键词：
Adult Amphetamines Animals Autopsy Axon Biological Models Brain Brain region Candidate Disease Gene Cells Cephalic Chemicals Chondroitin Sulfate Proteoglycan Cicatrix Clinical Cluster Analysis Complementary DNA Data Degenerative Disorder Dorsal Dose Event Failure Fascicle Fiber Functional disorder Gene Expression Gene Expression Profile Gene Expression Profiling Genetic Glial Fibrillary Acidic Protein Glutamates Goals Growth Growth Associated Protein 43 Growth Inhibitors Human Image Immunohistochemistry Impaired cognition Impairment Infiltration Injury Inorganic Sulfates Intervention Label Lesion Measurement Microglia Microscope Microscopy Molecular Molecular Profiling Mood Disorders Mus Natural regeneration Neocortex Nervous System Physiology Neuraxis Neurons Paralysed Phase Postdoctoral Fellow Preparation Proteoglycan Protocols documentation Rattus Recovery Recovery of Function Relative (related person)Research Research Personnel Role Sensory Serotonin Signal Transduction Site Stab Wounds Staining method Stains Stroke Techniques Testing Therapeutic Intervention Tilia Time Tissues Toxic effect Training Transgenic Mice Trauma Traumatic Brain Injury Unspecified or Sulfate Ion Sulfates Vestibular nucleus structure axon injury axon regeneration axonal degeneration cell type density genetic profiling in vivo injured insight neocortical nerve supply neuronal cell body public health relevance raphe nuclei sensor serotonin transporter therapy development tissue fixing two-photon

项目摘要

DESCRIPTION (provided by applicant): Following localized trauma, damaged axons in the adult mammalian central nervous system (CNS) regress, and subsequent regeneration of these damaged axons is very limited. This failure of regeneration strongly impedes recovery of CNS function and contributes to paralysis, sensory dysfunction and cognitive impairment. To date, the study of brain axon regeneration has almost exclusively relied upon postmortem analysis of fixed tissue from intact preparations, which yields static images. These snapshots are suboptimal for evaluating therapeutic interventions, as they often fail to distinguish regenerating axons from sprouting of undamaged fibers or spared axons at the lesion site. We have developed a model system in which long-distance regeneration of axons can be studied with time-lapse imaging in the intact adult mouse brain. Systemic treatment of adult rats with p-chloro-amphetamine (PCA), causes rapid regression of dorsal raphe serotonin axons, followed by a slow return of serotonergic innervation over many weeks. The Linden lab has adapted this PCA protocol to adult BAC transgenic mice in which the complete extent of serotonin neurons is labeled with EGFP. Using a two-photon microscope and a cranial window, we have repeatedly imaged the same volume of neocortex and thereby tracked serotonergic axons before and = 26 weeks after lesion with PCA to provide time-lapse measurements of identified surviving, regressing and regenerating fibers. Here, I propose to extend this model system and shift towards mechanistic inquiry. Aim 1. Do serotonin axons regenerate following a stab injury to the neocortex? I propose to repeat immunohistochemistry and in vivo time-lapse imaging of serotonin axons, replacing PCA treatment with a glial-scar inducing stab injury. My goal is to have two well-defined model systems for axonal damage and regeneration, one conventional, pan-cellular and glial- scar-forming and the other cell-type-specific and non-scar forming in order to compare molecular interventions and candidate therapies for functional recovery. Aim 2. Do serotonin neurons of the dorsal raphe have a unique basal gene expression profile that underlies their unusual capacity for axonal regeneration? Or might the crucial gene expression events in these cells only become evident following PCA or stab- evoked injury? I propose to perform single-cell genetic profiling to quantify gene expression patterns within serotonin neurons prior to axonal damage, immediately following PCA or stab-evoked injury, and after axonal regeneration. This will provide candidate genes for manipulation to alter regeneration.