Ion Channels and Excitability in the Peripheral Vestibular System

周围前庭系统的离子通道和兴奋性

• 批准号: 10361492
• 负责人: Katherine Janet Rennie
• 金额: $ 38.5万
• 依托单位: UNIVERSITY OF COLORADO DENVER
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-04-01 至 2026-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10361492
• 关键词: 3-Dimensional; Action Potentials; Adult; Afferent Neurons; Artificial Implants; Axon; Biophysics; Brain; Cells; Characteristics; Code; Crista ampullaris; Custom; Data; Dendrites; Development; Electric Stimulation; Electrophysiology (science); Epithelial; Equilibrium; Exhibits; Face; Fiber; Frequencies; Functional disorder; Future; Generations; Geometry; Gerbils; Goals; Hair; Hair Cells; Implant; Individual; Ion Channel; Kinetics; Label; Laboratories; Mediating; Membrane Potentials; Modeling; Motion; Nature; Nerve Fibers; Organ; Patients; Pattern; Peripheral; Pharmacologic Substance; Pharmacology; Pharmacotherapy; Phase; Physiologic pulse; Physiological; Population; Potassium Channel; Preparation; Process; Property; Prosthesis; Protocols documentation; Regulation; Rodent; Role; Sensory; Shapes; Signal Transduction; Slice; Stimulus; Synapses; System; Testing; Tetrodotoxin; Tissues; Type I Hair Cell; Type II Hair Cell; Utricle structure; Variant; Vestibular Hair Cells; Work; afferent nerve; analog; cell type; combat; cyclic-nucleotide gated ion channels; density; dimorphism; effective therapy; electrical property; equilibration disorder; extracellular; implant design; insight; mathematical model; novel; novel therapeutics; otoconia; patch clamp; postnatal; receptor; regional difference; relating to nervous system; response; therapeutic target; tool; vestibular prosthesis; voltage; voltage clamp

Project Summary Approximately 8 million adults in the US suffer from balance impairment due to damage to the peripheral vestibular system, but effective treatments for balance dysfunction are lacking. Vestibular hair cells within vestibular canal and otolith organs convert motion into receptor potentials and sensory information is relayed to the brain by action potentials (APs) in vestibular afferent nerves. Afferents in central zones (CZ) of vestibular neuroepithelia exhibit different responses to vestibular stimuli than afferents in peripheral zones (PZ). The nature of the neural code conveying vestibular information in distinct afferent types is poorly understood. There are 3 types of vestibular afferents: calyx-only afferents innervate one or more type I hair cells, bouton dendrites innervate type II hair cells and dimorphic afferents contact both hair cell types. Our goal is to elucidate distinct AP firing mechanisms in afferents with calyx terminals to better understand vestibular coding. Calyx-only afferents are present solely in CZ and have irregular firing patterns, whereas dimorphic afferents exist in both CZ and PZ and have regular firing patterns. To achieve our goal we will refine novel preparations of vestibular cristae and utricles, developed by our laboratory, as tools to study calyx-bearing afferents in CZ and PZ of gerbil neuroepithelia. Electrophysiological, hair bundle stimulation, immunohistochemical and pharmacological approaches will allow characterization of ion channels in afferent fibers in developing and mature epithelia. In Aim 1 we will determine the contributions of K+ channels and hyperpolarization-activated cyclic nucleotide- gated channels to AP firing in CZ and PZ afferents. Aim 2 will test the hypotheses that Nav1.6 channels with transient and resurgent characterisitics contribute uniquely to AP firing in mature PZ dimorphs. In Aim 3 we will incorporate ion channel data from Aims 1 and 2 into a novel, custom-written three dimensional mathematical model of the calyx to provide insight into our zonally-driven experimental findings. To determine how channel localization directly impacts AP firing, identified channel types will be strategically placed on the inner and outer faces of the calyx terminal and associated axon and channel density varied. Our results will clarify how sensory information is conveyed and how zonal encoding is generated within segregated vestibular afferents. Our data will inform development of vestibular neurotherapeutics targeting specific groups of ion channels in afferent nerves. Existing vestibular prosthetic implants attempt to restore normal vestibular function by direct electrical stimulation of vestibular afferents. A clearer understanding of AP generation and propagation within vestibular afferent sub-types is needed to inform appropriate electrical stimulation parameters. Results from this work could provide important new information on vestibular afferent coding and inform development of pharmaceutical and electrical strategies to combat vestibular dysfunction.

项目总结