NERVE-TARGET CELL INTERACTION IN TASTE BUD MAINTENANCE

外周味觉系统表现出显著的感觉神经 可塑性。味蕾感受器细胞不断更新并相互作用 神经紧张地动弹不得。此外，味觉神经对损伤的反应是 再生为舌上皮，效果显著。而当 味觉中感觉神经可塑性的结构特征是已知的，其 人们对神经化学底物知之甚少。最近，一些分子 各种因素与味觉神经营养不良有关。仓鼠是一只 这种方法的关键模型是因为菌芽萎缩，但芽却萎缩 在去神经后不会消失，允许评估残留的芽细胞 对于它们相对于被支配的细胞的差异以及在 神经再支配。相比之下，仓鼠的叶芽确实会在 去神经，可以与持久的菌芽进行比较。仓鼠 菌芽在位于中央的生殖细胞中表达NCAM、NSE和CGRP。在……里面 失去神经的花蕾，这些细胞急剧减少。可识别的特征 神经支配和去神经支配的芽中免疫阳性细胞的数量尚不清楚，以及 芽细胞重新获得神经支配的过程，目前还不清楚。电子 显微镜(EM)结合免疫细胞化学(IC)在正常芽中将 识别NCAM、NSE和CGRP免疫阳性细胞的类型， 例如，暗细胞或亮细胞，以及免疫反应细胞是否与神经突触 纤维。在慢性失神经的芽中，以及有再生神经的芽中，EM 同样将识别免疫阳性的生殖细胞类型和任何感受器 联系人。一种新的四甲基罗丹明葡聚糖胺离子电泳法 用于标记单个味蕾和它们的神经将评估时机 再神经支配相对芽IC的数量。最近出乎意料的 近端稀疏的CGRP免疫阳性神经纤维的观察 感觉神经缺失的芽出现了。关于这些纤维的来源和 它们可能对残留的芽细胞产生营养影响。其胞体 这些纤维的Oigin将通过TRDA标记在慢性感觉中确定 无精打采的动物。为了更好地描述真菌的分子性质 味蕾在退化和再生过程中，已经被证明是 在用于评估细胞-细胞识别的其他感觉系统中有用， 分化受体细胞和生长的轴突，除了用于 抗NCAM、-NSE和-CGRP。这些标记的使用将扩展到包括 金黄地鼠舌咽神经切断后叶状芽的研究。这将是 允许舌前部和后部味蕾的种内比较 对去神经反应明显不同的领域。这个 这种差异可能与不同的胚胎学起源有关 两个味蕾领域，即外胚层和内胚层衍生品，将 加强资料解释。

The peripheral gustatory system exhibits remarkable receptoneural plasticity. Taste bud receptor cells are continuously renewed and interact dynamically with nerves. Moreover, taste nerves respond to injury by regenerating to the tongue epithelium with great effectiveness. While structural features of receptoneural plasticity in taste are known, its neurochemical substrates are poorly understood. Recently, a few molecular factors have been associated with gustatory neurotrophism. The hamster is a critical model in this approach because fungiform buds atrophy, but the buds do not disappear after denervation, allowing the residual bud cells to be assessed for their differences relative to innervated cells as well as during reinnervation. In contrast, hamster foliate buds do disappear after denervation, allowing comparison with persistent fungiform buds. Hamster fungiform buds express NCAM, NSE and CGRP in centrally located gemmal cells. In denervated buds, these cells are dramatically reduced. The identifying features of immunopositive cells in innervated and denervated buds are not known, and the process by which bud cell become reinnervated, not understood. Electron microscopy (EM) combined with immunocytochemistry (IC) in normal buds will identify NCAM-, NSE- and CGRP-immunopositive cells with respect to their type, e.g., dark or light cells, and whether immunoreactive cells synapse with nerve fibers. In chronically-denervated buds, and buds with regenerating nerves, EM similarly will identify immunopositive gemmal cell types and any receptoneural contacts. A new tetramethylrhodamine dextran amine (TRDA) iontophoretic method for labeling single taste buds and their innervation will evaluate the timing and quantity of reinnervation relative to bud IC. Recent unexpected observations of sparse CGRP-immunopositive nerve fibers near some sensory-denervated buds raise.questions about the source of these fibers and their possible trophic influence upon residual bud cells. The cell bodies of oigin of these fibers will be determined by TRDA labeling in chronic sensory denervated animals. To better characterize the molecular nature of fungiform taste buds during degeneration and reinnervation, markers that have proven useful in other sensory systems for evaluating cell-cell recognition, differentiating receptor cells and growing axons, will be used in addition to anti-NCAM, -NSE and -CGRP. Use of these markers will be extended to include study of hamster foliate buds after glossopharyngeal nerve section. This will permit intraspecies comparison of anterior and posterior lingual taste bud fields which have responses to denervation that are dramatically different. The possibility that this difference relates to the different embryological origin of the two taste bud fields, i.e. as ectoderm vs. endoderm derivatives, will enhance the data interpretation.