Modulation of synaptic properties at the auditory Golgi-to-granule cell synapse

听觉高尔基体到颗粒细胞突触突触特性的调节

• 批准号: 8878212
• 负责人: Daniel Boyd Yaeger
• 金额: $ 1.69万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-07-01 至 2015-07-14
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8878212
• 关键词: Acetylcholine; Acoustic Nerve; Action Potentials; Agonist; Auditory; Auditory system; Axon; Cells; Chelating Agents; Cholinergic Agonists; Cholinergic Fibers; Cholinergic Receptors; Cytoplasmic Granules; Data; Disease; Dorsal; Ear; Efferent Neurons; Egtazic Acid; Electric Stimulation; Fiber; Frequencies; Glutamates; Goals; Golgi Apparatus; Health; Inhibitory Synapse; Laboratories; Medial; Medical; Membrane; Microscopy; Modeling; Neuromodulator; Pathway interactions; Physiological; Play; Presynaptic Terminals; Probability; Process; Property; Receptor Activation; Regulation; Role; Site; Sound Localization; Source; Sum; Synapses; Synaptic plasticity; Testing; Time; Tinnitus; Training; Vesicle; Work; cholinergic; dorsal cochlear nucleus; extracellular; granule cell; in vivo; mathematical model; metabotropic glutamate receptor 2; mossy fiber; neurotransmission; novel; optogenetics; presynaptic; receptor; research study; response; somatosensory; transmission process; two-photon; vesicular release

DESCRIPTION (provided by applicant): The dorsal cochlear nucelus (DCN) is an early auditory processing center that integrates auditory and nonauditory information. The role of nonauditory input to the DCN is not understood, but it may play a role in sound localization by the DCN and in certain forms of the auditory disorder tinnitus. Nonauditory input to the DCN is relayed to the principal cells of the DCN by granule cells. Granule cells are subject to prominent inhibition from Golgi cells, making Golgi cells well situated to control the flow of nonauditory information between granule cells and principal cells. I have identified two novel types of neuromodulators, cholingeric and type 2 metabotropic glutamate (mGluR2) receptor agonists, that decrease the size of IPSCs at the Golgi-to- granule cell synapse. Anatomical studies suggest that glutamatergic inputs likely to activate Golgi cell mGluR2 receptors carry non-auditory information, whereas cholinergic fibers may carry indirect auditory input. Thus, the Golgi-to-granule cell synapse may be dynamically regulated in response to nonauditory and auditory input. The goal of this proposal is to determine the key functional properties of the Golgi-to-granule cell synapse and how these properties are regulated by release of endogenous neuromodulators. The experiments in Aim 1 will test the hypothesis that the Golgi-to-granule cell synapse is a low release probability (Pr) synapse and that neuromodulators inhibit this synapse through reducing Pr and the number of release sites. Multiple probability fluctuation analysis will be used to determine the synaptic parameters of the Golgi-to-granule synapse and how these parameters are changed by cholinergic and mGluR2 agonists. The effect of cholinergic and mGluR2 agonists on Ca2+ influx in Golgi cell synaptic boutons will be examined using 2-photon microscopy. Data obtained during trains of IPSCs at the Golgi-to-granule cell synapse will be used to develop a model for short- term synaptic plasticity at this synapse. The experiments in Aim 2 will examine whether release of endogenous neuromodulators can regulate the Golgi-to-granule cell synapse and will test the hypothesis that concurrent release of acetylcholine and glutamate has a supralinear effect on inhibition of IPSCs at this synapse. Using optogenetics to stimulate cholinergic fibers and extracellular stimulation to activate mossy fibers, the effect of release of endogenous acetylcholine and glutamate on IPSCs at the Golgi-to-granule cell synapse will be examined. The number of Ca2+ channels required to open to trigger release of a vesicle at the Golgi-to-granule cell synapse is a major determinant of whether concurrent release of endogenous acetylcholine and glutamate, as likely occurs in vivo, has a linear or supralinear effect on inhibition of IPSCs at this synapse. Membrane- permeant Ca2+ chelators will be used to provide a qualitative estimate of the number of Ca2+ channels required to open to trigger release at the Golgi-to-granule cell synapse. Lastly, the effect of concurrent release o endogenous acetylcholine and glutamate on the Golgi-to-granule cell synapse will be determined.

描述（由申请人提供）：耳蜗背核（DCN）是一个早期的听觉处理中心，整合听觉和非听觉信息。 DCN 的非听觉输入的作用尚不清楚，但它可能在 DCN 的声音定位以及某些形式的听觉障碍耳鸣中发挥作用。 DCN 的非听觉输入由颗粒细胞转发到 DCN 的主要细胞。颗粒细胞受到高尔基细胞的显着抑制，使高尔基细胞能够很好地控制颗粒细胞和主细胞之间的非听觉信息流。我已经确定了两种新型神经调节剂：胆碱和 2 型代谢型谷氨酸 (mGluR2) 受体激动剂，它们可以减小高尔基体到颗粒细胞突触处 IPSC 的大小。解剖学研究表明，可能激活高尔基细胞 mGluR2 受体的谷氨酸输入携带非听觉信息，而胆碱能纤维可能携带间接听觉输入。因此，高尔基体到颗粒细胞的突触可以响应非听觉和听觉输入而动态调节。该提案的目标是确定高尔基体到颗粒细胞突触的关键功能特性以及这些特性如何通过内源性神经调节剂的释放进行调节。目标 1 中的实验将检验以下假设：高尔基体到颗粒细胞突触是低释放概率 (Pr) 突触，并且神经调节剂通过减少 Pr 和释放位点数量来抑制该突触。多重概率波动分析将 用于确定高尔基体到颗粒突触的突触参数以及胆碱能和 mGluR2 激动剂如何改变这些参数。将使用 2 光子显微镜检查胆碱能和 mGluR2 激动剂对高尔基细胞突触布顿中 Ca2+ 流入的影响。在高尔基体到颗粒细胞突触的 IPSC 序列中获得的数据将用于开发该突触的短期突触可塑性模型。目标 2 中的实验将检查内源性神经调节剂的释放是否可以调节高尔基体到颗粒细胞的突触，并将检验乙酰胆碱和谷氨酸的同时释放对该突触处 IPSC 的抑制具有超线性作用的假设。利用光遗传学刺激胆碱能纤维和细胞外刺激激活苔藓纤维，将检查内源性乙酰胆碱和谷氨酸的释放对高尔基体到颗粒细胞突触的 IPSC 的影响。打开以触发高尔基体到颗粒细胞突触处的囊泡释放所需的 Ca2+ 通道数量是内源性乙酰胆碱和谷氨酸的同时释放（如体内可能发生的那样）是否具有线性或超线性影响的主要决定因素。在此突触处抑制 IPSC。膜渗透性 Ca2+ 螯合剂将用于提供打开触发高尔基体到颗粒细胞突触释放所需的 Ca2+ 通道数量的定性估计。最后，将确定同时释放内源性乙酰胆碱和谷氨酸对高尔基体到颗粒细胞突触的影响。