Plasticity of the Regenerating Taste System

味蕾对支配它们的神经纤维的依赖已经被用作理解神经/目标相互作用的模型。失去神经支配会导致味蕾失去正常的形态外观，而神经支配的恢复会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前体细胞最终形成能够传递味觉信息的成熟功能细胞的动态生物过程的理想选择。我们实验室以前的工作表明，成人的味觉再生系统特别容易受到环境操纵的影响。成年大鼠单侧酪索神经切断术和低钠饮食相结合，可导致味蕾和再生神经的各种功能和解剖学改变。此外，这种影响并不局限于舌头的切割侧，因为完整的对侧也会发生深刻的功能和解剖学变化。为了扩展这些发现，在对照组大鼠和成年后单侧切断鼓索神经后喂食全盐或缺盐饮食的大鼠中，将记录单个膝状神经节细胞在体内操纵舌上皮电压时的神经生理味觉反应。协调的形态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，将探讨神经活动和免疫系统的作用，以进一步了解退化/再生的外周味觉系统可能涉及的潜在机制。拟议的研究将提供关于以下方面的新信息：L)神经生理变化的性质、反应变化的部位和味觉感受器细胞中传导元件的生物物理变化，这是神经切断与饮食钠限制相结合的结果；2)免疫系统和神经活动在调节生理效应中的作用3)时间、去神经支配和饮食钠限制对单个菌状乳头中鼓索神经支配模式的稳定性和准确性的影响1和4)切割诱导的味蕾细胞增殖和膝状神经节细胞数量的变化。这些研究的结果将提供关于正常和再生的成人周围味觉系统中外周味觉反应的可塑性和神经支配组织的进一步信息。它们还将有助于确定饮食对再生神经以及感觉感受器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.