EFFERENT INNERVATION OF IDENTIFIED VESTIBULAR AFFERENTS

本研究的目的是研究大脑皮层的传出神经支配。 外周前庭器官化学成分知识 脑干传出神经元向外周的投射 迷路可能有助于了解前庭传出神经的作用 健康和疾病的系统。最近的研究表明， 传出核中的神经递质可能是异质的 神经化学和外周靶点。的这个建议 异质性，如果得到证实，将改变我们长期持有的观点， 前庭传出神经是一种非特异性系统。本研究的目的是 根据以下条件定义灰鼠传出神经元的亚群： 他们的脑干位置，他们对一个，另一个或两者的投射 耳朵，它们的神经化学特性和它们在头发上的末梢 细胞、肾盏和其他传入突起。具体目标是： 描述传出神经的解剖学和神经化学亚群 脑干传出神经元中的神经元使用逆行示踪剂， 递质免疫组化，和2）涉及中央 前庭传出神经元的亚群到它们的终末 外围脑干中的传出神经元将通过 逆行示踪剂注射到前庭末梢 并将同时通过使用 几种假定的神经递质（乙酰胆碱， 降钙素基因相关肽、一氧化氮合酶、甲硫氨酸脑啡肽和 其他）。该分析将扩展到电子 显微免疫组织化学方法将用于表征 神经化学上独特的传出终扣，根据他们的 在感觉上皮中的终止，也就是说，通过传入类 （花萼，二形或小花冠）或区域（中心或周边），他们 使神经活动。前庭传入神经将通过以下方式识别： 细胞外HRP注射、钙视网膜蛋白免疫组织化学或其他 手段毒蕈碱受体亚型的分布也将是 为了了解传入神经对 刺激传出神经。该项目的意义在于， 对构成人口的各种要素的精确认识 传出神经元，和他们的目标在周边，将进一步我们的 理解脑干对周围感觉处理的控制。它 希望通过这项工作， 仅仅是为了定义脑干中的亚群，而不建立它们的 与外围的关系。也不足以说明 外围设备终端，而不说明其在 内脏其目的是产生一个关于 传出神经的结构基础， 可以推导出可验证的假设。

The purpose of this grant is to investigate the efferent innervation of the peripheral vestibular apparatus. Knowledge of the chemical composition and projections of the efferent neurons in the brainstem to the peripheral labyrinth may help to understand the role of the vestibular efferent system in health and disease. Recent work has suggested that the neurons in the efferent nucleus may be heterogeneous in their transmitter neurochemistry and in their peripheral targets. This suggestion of heterogeneity, if confirmed, would change our long-held view that the vestibular efferents are a nonspecific system. The goal of this study is to define subpopulations of efferent neurons in the chinchilla based on their brain stem locations, their projections to one, the other or both ears, their neurochemical identities and their peripheral endings on hair cells, calyces and other afferent processes. Specific aims are: l) to characterize anatomical and neurochemical subpopulations of efferent neurons in the brainstem efferent neurons using retrograde tracers and transmitter immunohistochemistry, and 2) to relate the central subpopulations of vestibular efferent neurons to their terminations in the periphery. Efferent neurons in the brainstem will be identified by means of retrograde tracer injections into the peripheral vestibular apparatus and will be simultaneously characterized immunohistochemically by the use of antibodies to several putative neurotransmitters (acetylcholine, calcitonin gene-related peptide, nitric oxide synthase, met-enkephalin and others). The analysis will be extended to the periphery where electron microscopic immunohistochemical methods will be used to characterize neurochemically distinctive efferent boutons according to their terminations in the sensory epithelium, that is, by the class of afferents (calyx, dimorphic or bouton) or region (central or peripheral) that they innervate. Vestibular afferents will be identified by means of extracellular HRP injections, calretinin immunohistochemistry, or other means. The distribution of muscarinic receptor subtypes will also be examined in an attempt to understand the slow response of afferents to stimulation of the efferents. The significance of this project is that a precise knowledge of the various elements comprising the population of efferent neurons, and their targets in the periphery, will further our understanding of brain stem control of peripheral sensory processing. It is hoped that as a result of this work, it will no longer be sufficient merely to define subgroups in the brain stem without establishing their relationship to the periphery. Nor will it be sufficient to illustrate peripheral terminations without stating their specific location within the endorgan. The intent is to produce a body of knowledge about the structural basis of the efferents from which physiologically and pharmacologically testable hypotheses can be derived.