GLUTAMATE NEUROTRANSMISSION IN RAT TASTE BUDS

大约有200万美国成年人患有味觉障碍。 还有气味。这些人，特别是老年人和那些正在接受治疗的人 对于唾液腺肿瘤的放射治疗，营养状况是受损的。 更重要的是，这些个体失去了感知的保护性能力 变质的和潜在有毒的食物。我们对味觉的有限理解 人们的看法阻碍了我们解决这些问题的能力。特别是， 味觉在识别突触方面落后于其他感官 涉及外周感觉器官的机制。谷氨酸一直是 被认为是味蕾中的一种神经递质，但证据还很远 需要对患者进行全面、详细的功能检查。这些实验 介绍了一种研究突触的新方法 在大鼠味蕾中传播。这种方法是用凝胶电泳法注射 葡聚糖偶联钙绿原位进入完整的味蕾，随后 舌片单个味觉细胞内[Ca~(2+)]i变化的可视化。 申请人将使用这一新方法记录激活 味觉细胞中的神经递质受体并检验这一假说 谷氨酸是味蕾中的一种递质。将使用CA2+成像，并且 重点将放在1)确定味蕾是否表达功能性突触 谷氨酸受体；2)确定存在哪些谷氨酸受体 味觉细胞；以及3)测试感觉神经是否提供传出 味觉细胞的谷氨酸能输入。这一系列实验将提供一种 突触谷氨酸受体的功能鉴定和特性研究 在味觉细胞中。此外，该应用程序将解决重要的问题 谷氨酸受体是否在突触间介导传出传递 味觉细胞和感觉轴突。谷氨酸能突触的证据和 味蕾的传出调节将改变当前的感官模型 信息在外围味觉系统中进行编码。

Approximately two million adult Americans suffer from disorders of taste and smell. In these individuals, especially the elderly and those undergoing radiation therapy for salivary gland tumors, nutritional status is compromised. More importantly, these individuals lose the protective ability to perceive spoiled and potentially toxic foods. Our limited understanding of taste perception has hindered our ability to address these issues. In particular, taste lags behind other senses with respect to the identification of synaptic mechanisms involved in the peripheral sensory organ. Glutamate has been proposed as a putative neurotransmitter in taste buds but the evidence is far from complete and a detailed functional examination is needed. The experiments outlined in this application introduce a new method to study synaptic transmission in rat taste buds. This method is the electrophoretic injection of dextran-coupled Calcium Green into intact taste buds in situ, followed by the visualization of changes in [Ca2+]i in single taste cells in lingual slices. The applicant will use this new approach to record activation of neurotransmitter receptors in taste cells in situ and test the hypothesis that glutamate is a transmitter in taste buds. Ca2+ imaging will be used and the focus will be on 1) determining whether taste buds express functional synaptic glutamate receptors; 2) identifying which glutamate receptors are present in taste cells; and 3) testing whether sensory innervation provides efferent glutamatergic input to taste cells. This series of experiments will provide a functional identification and characterization of synaptic glutamate receptors in taste cells. Moreover, this application will address the important question of whether glutamate receptors mediate efferent transmission at synapses between taste cells and sensory axons. Evidence for glutamatergic synapses and for efferent modulation in taste buds will modify current models of how sensory information is encoded in the peripheral gustatory system.