Plasticity of the Regenerating Taste System

味蕾对支配它们的神经纤维的依赖性已被用作理解神经/靶标相互作用的模型。神经支配的丧失导致味蕾正常形态外观的丧失，而神经支配的恢复导致味蕾形态和功能的恢复。因此，退化和再生的外周味觉系统是研究动态生物过程的理想选择，在这个过程中，祖细胞最终形成成熟的、有功能的、能够传递味觉信息的细胞。我们实验室以前的工作表明，成人再生味觉系统特别容易受到环境操纵。结合单侧虎索神经切断术和低钠饮食，成年大鼠的味蕾和再生神经的各种功能和解剖改变。此外，影响并不局限于舌的切面，因为深刻的功能和解剖改变也发生在完整的对侧。为了扩展这些发现，我们将在对照大鼠和成年后单侧切除鼓室索神经后，分别饲喂含盐或缺盐饮食的大鼠的舌上皮内，记录单膝状神经节细胞在操纵电压时的神经生理味觉反应。协调形态学研究将检查与受体细胞和相关神经元件的维持和再生有关的各种过程。最后，我们将探讨神经活动和免疫系统的作用，以进一步了解周围味觉系统退化/再生的可能潜在机制。拟议的研究将提供以下方面的新资料：L)神经切片和饮食钠限制导致的味觉受体细胞中转导元件的神经生理变化的性质、反应改变的部位和生物物理变化；2)免疫系统和神经活动在介导生理效应中的作用；3)时间、神经支配的影响；饮食钠限制对单菌类乳头状脊索神经支配模式的稳定性和准确性的影响(1)和(4)切片诱导的味蕾细胞增殖和束状神经节细胞数量的变化。这些研究结果将进一步揭示正常和再生成人外周味觉系统的可塑性和神经解剖学组织。它们还将有助于确定饮食对神经再生、感觉受体功能和解剖学的作用。

The dependence o taste buds on the nerve fibers that innervate them has been use as a model to understand nerve/target interactions. Loss of innervation results in a loss of the normal morphological appearance of taste buds, while restoration of innervation results in a restoration of taste bud morphology and function. Therefore, the degenerating and regenerating peripheral gustatory system is ideal for studying dynamic biological processes which progenitor cells ultimately form mature, functional cells capable of transducing taste information. Previous work in our laboratory showed that the adult regenerating gustatory system is especially susceptible to environmental manipulations. Combining unilateral chorda tyrnpani nerve section and low sodium diet in adult rats results in a variety of functional and anatomical alterations in both taste buds and in the regenerating nerve. Furthermore, the effects are not limited to the sectioned side of the tongue because profound functional and anatomical alterations also occur in the intact, contralateral side. To extend these findings, neurophysiological taste responses from single geniculate ganglion cells will be recorded during manipulation of voltages across the lingual epithelium in vivo in control rats and in rats fed either a NaCl- replete or NaCl-deficient diet after unilateral sectioning of the chorda tympani nerve at adulthood. Coordinated morphological studies will examine a variety of processes involved with maintenance and regeneration of receptor cells and associated neural elements. Finally, the role of neural activity and of the immune system will be explored to further an understanding of possible underlying mechanisms involved in the degenerating/regenerating peripheral taste system. Proposed studies will provide new information about: l) the nature of neurophysiological changes, the site of response alterations, and biophysical changes in the transducing elements in taste receptor cells as a result of nerve sectioning coupled with dietary sodium restriction, 2) the role of the immune system and neural activity in mediating physiological effects 3) the effects of time, dennervation, and dietary sodium restriction on the stability and accuracy of chorda rympani innervation patterns in single fungiform papillae1 and 4) section-induced changes in taste bud cell proliferation and in the numbers of geniculate ganglion cells. Findings from these studies will provide further information about the plasticity of peripheral taste responses and the neuroanatornical organization in the normal and regenerating adult peripheral gustatory system. They will also be useful in determining the role that diet has on regenerating nerves and on sensory receptor function and anatomy.