GLUTAMATE AND SENSORY PROCESSING IN THE OLFACTORY SYSTEM

描述(改编自《调查者摘要》)：嗅觉 脊椎动物系统已经成为一种越来越重要的模式 感官信息处理的研究。嗅球和 初级嗅觉古皮质是感觉加工的主要场所 在这个系统中。尽管它的解剖学和突触回路 系统已被广泛研究，嗅觉的分子事件 突触和嗅觉神经元内介导嗅觉信息 加工、联想学习和记忆还没有被描述出来。 谷氨酸与两类受体的偶联：配体门控离子通道 (离子亲和性受体)，以及那些与细胞内信号传递耦合的受体 鸟嘌呤核苷酸结合蛋白或G蛋白途径 (代谢性受体)。后一类人在 谷氨酸对钙、蛋白水解酶的作用及其调控 突触的力量。这类受体的表达显著 通过生理学和分子研究，在嗅觉区域普遍存在， 提示谷氨酸在信号和信息中起重要作用 正在处理。然而，由于缺乏特定的药理工具， 限制了我们对G蛋白偶联谷氨酸功能的了解 感受器。这项提议将使用非洲爪哇的卵母细胞和神经细胞 表达克隆受体以解决三个问题：1)什么是 不同G蛋白偶联受体的结构特征 决定他们药理的嗅觉系统？2)什么是 G蛋白偶联谷氨酸受体的细胞效应 它们在嗅神经元中的作用？3)G蛋白是如何偶联的 嗅觉神经元中的谷氨酸受体对正常 这些神经元的功能呢？调查人员将使用cDNA 代谢型谷氨酸受体和从嗅球中分离其他受体 和嗅觉皮质来测试关于这些特征的假设 决定它们药理的受体。这将对 了解介导已知药理作用的受体 试剂，也许可以让开发出更具体和 有效的药理工具。他们将通过膜片钳来确定 神经细胞系和原代神经元培养的记录 受体cDNA的表达及其在门控中的作用 以及对特定离子通道的调制来确定这些受体如何 影响神经元兴奋。他们还将确定解剖结构 这些受体mRNAs在嗅觉神经元中的表达及应用 抗血清以确定它们是否在脑组织的特定区域表达 嗅觉回路，包括嗅觉突触。他们还会尝试 剖析个体G蛋白偶联的重要信号 谷氨酸受体通过结合激活嗅觉神经元 单个神经元的生理学和分子生物学研究及阻断 它们各自的代谢性受体的表达和检测 谷氨酸对离子通道的调节和作用的差异 细胞内信号通路。通过定义精确的药理学 这些受体，了解它们在神经元和 确定它们在嗅觉神经元中的表达模式 突触，研究人员将开始阐明分子事件 嗅觉信息的基础处理。

DESCRIPTION (Adapted from the Investigator's Abstract): The olfactory system of vertebrates has become an increasingly important model for the study of processing of sensory information. The olfactory bulb and primary olfactory paleocortex are the major sites of sensory processing in this system. Although the anatomy and synaptic circuitry of this system have been studied extensively, the molecular events at olfactory synapses and within olfactory neurons mediating olfactory information processing, associative learning and memory have not been characterized. Glutamate couples to two classes of receptors: ligand-gated ion channels (ionotropic receptors), and those coupled to intracellular signalling pathways through guanyl nucleotide binding proteins or G proteins (metabotropic receptors). The latter group is potentially important in effects of glutamate involving calcium, kinases and modulation of synaptic strength. Expression of this class of receptors is remarkably prevalent in olfactory regions by physiologic and molecular studies, suggesting an essential role in glutamate signaling and information processing. However, the lack of specific pharmacologic tools has limited our understanding of the function of G protein-coupled glutamate receptors. This proposal will use Xenopus oocytes and neuronal cells that express cloned receptors to address three questions: 1) What are the structural features of different G protein-coupled receptors in the olfactory system that determine their pharmacology? 2) What are the cellular effects of G protein coupled glutamate receptors that determine their function in olfactory neurons? 3) How do G protein-coupled glutamate receptors in olfactory neurons contribute to the normal function of these neurons? The investigators will use cDNAs for metabotropic glutamate receptors and isolate others from olfactory bulb and olfactory cortex to test hypotheses about the features of these receptors that determine their pharmacology. This will be crucial to understand the receptors that mediate effects of known pharmacologic reagents and perhaps allow the development of more specific and effective pharmacologic tools. They will determine by patch-clamp recording of neuronal cell lines and primary neuronal cultures expressing the receptor cDNAs the effects of these receptors on gating and modulation of specific ion channels to determine how these receptors affect neuronal excitation. They will also determine the anatomic expression of these receptors mRNAs in olfactory neurons and use antisera to determine whether they are expressed in specific areas of the olfactory circuitry, including at olfactory synapses. They will also try to dissect the important signals that individual G protein-coupled glutamate receptors activate in olfactory neurons by combining physiologic and molecular studies in individual neurons and by blocking their expression of individual metabotropic receptors and measuring differences in glutamate effects on ion channel modulation and intracellular signaling pathways. By defining the precise pharmacology of these receptors, understanding their cellular effects in neurons and determining their pattern of expression in olfactory neurons and synapses, the investigators will begin to elucidate the molecular events underlying processing of olfactory sensory information.