MOLECULAR PHYSIOLOGY OF GLUTAMATE IN TASTE

与视觉和嗅觉不同，味觉还没有被广泛研究。 分子生物学的现代工具。该项目带来了一个 分子生物学、细胞生物学和生理学的综合 通过分析味蕾中的谷氨酸受体。谷氨酸是一种 重要的味觉刺激物（如谷氨酸盐、味精）。Responses to 在感觉纤维和大脑中记录了谷氨酸盐。 谷氨酸盐的心理物理学和享乐学方面的研究已经在 很长。然而，谷氨酸盐味道的最初事件，即 谷氨酸与膜结合受体的相互作用，仍然相对 未经研究。 因此，关于谷氨酸受体的关键信息 它们的分子结构，它们在味觉中的定位 细胞，它们的功能和调节都缺失了概述的实验 本计划项目将提供这些重要数据，并将 识别味觉刺激的第一个特异性受体。从长远 术语，这将为全面定义整个 味觉感受的外围序列--从配体结合到 感觉神经中的信号产生。调查结果还将增加 我们对有争议的食品添加剂味精的理解和认识。 我们计划项目的统一前提是， 味觉细胞中谷氨酸的味道与谷氨酸类似 大脑中的受体。脑谷氨酸受体形成2个大的延伸 离子型和代谢型受体家族。我们建议采取 这些分子生物学的最新信息的优势 研究味蕾中的谷氨酸受体。我们将 用简并引物进行PCR（聚合酶链反应）， 大脑受体来寻找味蕾中的新型谷氨酸受体。 从舌组织中选择PCR产物作为探针， 编码味觉特异性谷氨酸受体（Chaudhari）的全长cDNA。 我们将使用原位杂交来定位特定味道的mRNA 细胞和免疫细胞化学定位受体蛋白（罗珀）。我们 将进行味觉内源性谷氨酸受体的功能研究 细胞使用微电极记录技术。我们还将表达 在卵母细胞和异源哺乳动物细胞中克隆的谷氨酸受体 用膜片钳技术测量谷氨酸引起的电流 在不同的实验条件下（Kinnamon）。最后，我们将使用 条件性味觉厌恶，以研究 不同的受体（罗珀）。 通过将这三种方法整合到一个小型的、有重点的计划项目中， 我们将充分利用3的专业知识和热情， 独立、高效、高度互动的首席研究员。 在谷氨酸的分子生理学上获得的集体见解， 品味将远远超过个人所能达到的 这些研究人员的努力。

Unlike vision and olfaction, taste has not been examined extensively with the modern tools of molecular biology. This Program Project brings a synthesis of molecular biology, cell biology and physiology into the field of taste by analyzing glutamate receptors in taste buds. Glutamate is an important taste stimulus (e.g. monosodium glutamate, MSG). Responses to glutamate have been recorded in sensory fibers and from the brain. Psychophysical and hedonic aspects of glutamate have been researched at great length. Yet, the initial events in glutamate taste, namely the interaction of glutamate with membrane-bound receptors, remains relatively unstudied. Consequently, critical information about glutamate receptors in taste buds--their molecular structure, their localization in taste cells, their function and modulation--is missing. The experiments outlined in this Program Project will provide these important data and will identify the first specific receptor for a taste stimulus. In the long term, this will pave the way for a comprehensive definition of the entire peripheral sequence of events in taste reception--from ligand binding to signal generation in the sensory nerves. The findings will also increase our understanding and awareness of the controversial food additive, MSG. The unifying premise underlying our Program Project is that receptors that transduce the taste of glutamate in taste cells are similar to glutamate receptors in the brain. Brain glutamate receptors form 2 large extended families of ionotropic and metabotropic receptors. We propose to take advantage of recent information about the molecular biology of these receptors to investigate glutamate receptors in taste buds. We will conduct PCR (polymerase chain reaction) with degenerate primers based on brain receptors to search for novel glutamate receptors in taste buds. Selected PCR products from lingual tissue will serve as probes to isolate full-length cDNAs encoding taste-specific glutamate receptors (Chaudhari). We will use in situ hybridization to localize mRNAs to specific taste cells and immunocytochemistry to localize receptor proteins (Roper). We will conduct functional studies of glutamate receptors endogenous to taste cells using microelectrode recording techniques. We will also express cloned glutamate receptors in oocytes and in heterologous mammalian cells and use patch clamp techniques to measure currents elicited by glutamate under different experimental conditions (Kinnamon). Lastly, we will use conditioned taste aversion to investigate the significance for taste of pharmacologically distinct receptors (Roper). By integrating these three approaches in a small, focused Program Project, we will take full advantage of the expertise and enthusiasm of 3 independent, productive, and highly interactive principal investigators. The collective insights gained on the molecular physiology of glutamate in taste will be much greater than could be achieved from the individual efforts of these researchers.