NEUROPEPTIDES, ATP AND SUBMANDIBULAR GLAND FUNCTION

除了外周神经的“经典”神经递质外， 系统，乙酰胆碱和去甲肾上腺素，在调节 外分泌腺功能近年来已被证实， 其他药物，包括ATP和各种神经肽，包括血管活性 肠肽（VIP）。 在唾液腺中， 获得关于腺泡细胞功能的神经递质调节的研究。 然而，由于缺乏合适的模型系统， 了解唾液腺导管细胞神经递质调节 功能 最近，已经获得了形态学和生化数据， 这表明人下颌下腺HSG-PA细胞系 导管起源，具有正常导管的几个重要特征 细胞，因此，作为研究导管细胞的模型系统， 特定的功能及其通过神经递质的调节。 我们的研究 迄今为止已经证明HSG-Pa细胞中存在VIP受体， 与腺苷酸环化酶偶联，对于神经降压素和ATP，与腺苷酸环化酶偶联， 脂酶C已 其他初步证据表明激动剂- 刺激增加K+和C1-通量，以响应一个或多个 这些药物和这些反应的改变渗透挑战， 将细胞暴露于低渗培养基导致显著的 神经递质刺激的离子（K+）通量的增强，而高渗 介质阻断神经递质刺激的通量。 这项建议 重点是神经递质调节导管细胞离子运输和 渗透压变化对该调节的影响，使用HSG-PA细胞系 做模特 第一，VIP、神经降压素和ATP对单价 将评估离子通量。 跨细胞离子运动，研究在 Ussing chambers将测量激动剂引起的短路变化 电流与放射性同位素示踪剂和离子置换 实验来识别被运输的物种。 受体和非受体 细胞内信号传导通路的调节剂将用于关联 第二信使与离子流的变化和相互作用。 放射性配体结合将用于进一步表征受体 涉案 调查的第二个领域侧重于查明 介质渗透压变化调节离子转运的机制 由神经递质调节。 研究在离散的步骤， 细胞内信号传导过程（激动剂与受体结合; G蛋白 参与，第二信使的产生，K+通量的激活）将被 进行，以确定在信号通路中的点，其中渗透压 挑战影响K+通量的神经递质调节。 所有这些 这些研究有望大大提高我们对 VIP、神经降压素和ATP对唾液分泌过程的调节 导管细胞及其渗透环境中的作用扰动 调节这些神经递质的运输，从而有助于 为评价导管细胞- 在各种外分泌疾病状态下的特定功能及其调节。

In addition to the "classic" neurotransmitters of the peripheral nervous system, acetylcholine and norepinephrine, roles in the regulation of exocrine gland function have been demonstrated in recent years for several other agents, including ATP and various neuropeptides, including vasoactive intestinal peptide (VIP). In salivary glands, much information has been obtained concerning neurotransmitter regulation of acinar cell function. However, due to the lack of suitable model systems, relatively little is known about neurotransmitter regulation of salivary gland duct cell function. Recently, morphological and biochemical data have been obtained which indicate that the HSG-PA cell line, of human submandibular gland ductal origin, possesses several important characteristics of normal duct cells and thus holds much promise as a model system for studying duct cell- specific functions and their regulation by neurotransmitters. Our studies to date have documented the presence in HSG-Pa cells of receptors for VIP, coupled to adenylyl cyclase, and for neurotensin and ATP, coupled to phospholipase C. Additional preliminary evidence demonstrates agonist- stimulated increases in K+ and C1- fluxes in response to one or more of these agents and alterations of these responses by osmotic challenge, in which exposure of cells to hypotonic medium results in a dramatic enhancement of neurotransmitter stimulated ion (K+) flux whereas hypertonic medium blocks the neurotransmitter-stimulated fluxes. This proposal focuses on neurotransmitter regulation of duct cell ion transport and the effects of osmotic changes on that regulation, using the HSG-PA cell line as a model. First, regulation by VIP, neurotensin and ATP of monovalent ion fluxes will be evaluated. Transcellular ion movements, studied in Ussing chambers, will measure agonist-induced changes in short circuit current in conjunction with radioisotope tracer and ion replacement experiments to identify the transported species. Receptor and non-receptor modulators of intracellular signaling pathways will be used to correlate changes in, and interactions of, second messengers with ion fluxes. Radioligand binding will be used to further characterize the receptors involved. The second area of investigation focuses on identification of the mechanisms by which changes in medium osmolarity modulate ion transport regulation by the neurotransmitters. Studies at discrete steps in the intracellular signaling processes (agonist binding to receptor; G protein involvement, second messenger production, activation of K+ flux) will be performed to define the points in the signaling pathway where osmotic challenges affect neurotransmitter regulation of K+ flux. Together, these studies promise to increase substantially our understanding of the roles of VIP, neurotensin and ATP in regulation of secretory processes in salivary duct cells and the role perturbations in the cells' osmotic environment have in regulation of transport by these neurotransmitters, thus helping to establish a foundation for evaluating the role of alterations in duct cell- specific functions and their regulation in various exocrine disease states.