GLUTAMATE NEUROTRANSMISSION IN RAT TASTE BUDS

大约有200万成年美国人患有味觉障碍 还有嗅觉 在这些个体中，特别是老年人和那些经历 放射治疗的唾液腺肿瘤，营养状况受到损害。 更重要的是，这些个体失去了感知的保护能力， 变质和潜在有毒的食物。 我们对味觉的有限理解 这种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。 谷氨酸已经 它被认为是味蕾中的一种神经递质，但证据还远没有充分的证据。 需要进行全面和详细的功能检查。 实验 本文介绍了一种研究突触的新方法， 在大鼠味蕾中的传播。 该方法是电泳注射 葡聚糖偶联钙绿色原位进入完整的味蕾，然后是 舌切片中单个味觉细胞中[Ca 2 +]i变化的可视化。 申请人将使用这种新方法记录激活 神经递质受体在味觉细胞原位和测试的假设， 谷氨酸盐是味蕾中的一种传递物质。 将使用Ca 2+成像， 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）确定哪些谷氨酸受体存在于 味细胞;和3）测试感觉神经支配是否提供传出神经 味觉细胞的味觉输入。 这一系列实验将提供一个 突触谷氨酸受体的功能鉴定和表征 在味觉细胞中。 此外，该应用程序将解决重要的问题 谷氨酸受体是否介导突触的传出传递， 味觉细胞和感觉轴突。 有证据表明， 味蕾的传出调制将改变目前的模型， 信息被编码在外周味觉系统中。

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.