A New Model for In Vivo Vestibular Pharmacology

描述（由申请人提供）：本申请是一项探索性和发展性的建议，旨在设计、测试和制造一个实验模型，在这个模型中，内耳迷路的急性灌注可以用于前庭药理学的研究。这种新模型的主要优点是，药物操作可以直接引入迷宫，同时记录初级传入神经元的放电，代表前庭感觉上皮的输出。因此，可以直接确定操作对自发放电和刺激诱发放电的影响，从而使未来的研究能够解决当代药理学工具（例如受体激动剂和拮抗剂，电导特异性激动剂和拮抗剂等）适用的各种问题。两个假设将通过一组具体的目标来测试，这将充分测试模型的有效性。将构建一个灌注输送系统，解决关键技术问题，具体到外周前庭系统的基本功能，在其设计。初步研究已经确定了可能由灌注压力突然变化引起的传入放电中的潜在伪影。灌注输送系统将专门设计和制造，以消除或尽量减少这些工件。该系统的设计和制造将反映神经生物学和微流体工程的合作，利用微机电系统（MEMS）工程的工具构建一个微流体装置（芯片）来管理灌注液直接流向特制龙猫的内耳淋巴周围空间。灌注溶液的测试电池将用于解决特定溶液成分对毛细胞和传入神经元的可及性，传入神经元投射到整个嵴和室神经上皮。这些实验有电生理学和形态学组成部分，通过传入放电记录和前庭毛细胞对这些溶液的直接成像来提供测试溶液和监测效果。将进行实验，以验证第二个假设，即传入神经元中存在跨膜ampa受体调节蛋白（TARPs）。在为药理学操作的制备提供详细的直接测试的同时，这些实验也将解决TARPs在前庭传入事件中的功能。这些结果有可能激发对外周前庭系统感觉加工的新研究。

DESCRIPTION (provided by applicant): This application represents an exploratory and development proposal to design, test, and fabricate an experimental model in which acute perfusions of the inner ear labyrinth can be achieved for investigations of vestibular pharmacology. The principal advantage of this new model is that the pharmacologic manipulations can be introduced directly into the labyrinth while recording the discharge of primary afferent neurons, representing the output of vestibular sensory epithelia. Therefore, the effect of the manipulations on spontaneous and stimulus-evoked discharge can be directly determined, enabling future investigations addressing a wide variety of questions for which contemporary pharmacologic tools (e.g. receptor agonists and antagonists, conductance-specific agonists and antagonists, etc.) are applicable. Two hypotheses will be tested through a set of specific aims that will fully test the efficacy of the model. A perfusate delivery system will be constructed that addresses key technical issues, specific to the basic function of the peripheral vestibular system, in its design. Pilot studies have identified potential artifacts in afferent discharge that likely resulted from abrupt changes in perfusate pressure. The perfusate delivery system will be specifically designed and fabricated to eliminate or minimize these artifacts. The design and fabrication of this system will reflect a collaboration between neurobiology and microfluidics engineering, using tools of micro-electro- mechanical systems (MEMS) engineering to construct a microfluidics device (chip) to manage the flow of perfusate directly to the inner ear perilymphatic space of specially prepared chinchillas. A test battery of perfusate solutions will be utilized that address the accessibility of specific solution constituents to hair cells and afferent neurons projecting throughout the crista and utricular neuroepithelia. These experiments have electrophysiologic as well as morphologic components, whereby test solutions will be delivered and the effects monitored through afferent discharge recordings as well as from direct imaging of the incorporation of these solutions by vestibular hair cells. Experiments will be conducted that will test a second hypothesis regarding the presence of transmembrane AMPA-receptor regulatory proteins (TARPs) within the afferent neurons. While providing a detailed direct test of the efficacy of the preparation for pharmacologic manipulations, these experiments will also address the functionality of TARPs in vestibular afferents. These results have the potential to motivate a new line of investigation for sensory processing in the peripheral vestibular system. PUBLIC HEALTH RELEVANCE: The research to be conducted under this exploratory and development proposal will produce a mammalian model system through which direct testing of pharmaceutical agents can be conducted with respect to their influence on the inner ear vestibular system and the signals that are transmitted to the central nervous system. The results from this investigation will lead to future studies ameliorating our understanding of neurochemical and pharmacologic interactions within the inner ear. This system may also provide a test bed for new treatments of inner ear disorders, as well as contribute to the development of new therapies that will assist in neural rehabilitation of damaged inner ear tissues.