NEUROPEPTIDES, ATP AND SUBMANDIBULAR GLAND FUNCTION

神经肽、ATP 和颌下腺功能

• 批准号: 3221057
• 负责人: JOHN T TURNER
• 金额: $ 17.79万
• 依托单位: UNIVERSITY OF MISSOURI-COLUMBIA
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-08-01 至 1996-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3221057
• 关键词: acinar cell; adenosine triphosphate; biological signal transduction; exocrine glands; human tissue; ion transport; laboratory rat; neurotensin; neurotransmitter receptor; osmotic pressure; radiotracer; second messengers; submandibular gland; uridine; vasoactive intestinal peptide

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.

除了外周神经的“经典”神经递质 系统，乙酰胆碱和去甲肾上腺素，在调节 近年来，外分泌腺的功能已经被证明有几个 其他药物，包括ATP和各种神经肽，包括血管活性物质 肠肽(VIP)。在唾液腺中，许多信息已经被 获得有关腺泡细胞功能的神经递质调节。 然而，由于缺乏合适的模式系统，相对较少的是 已知唾液腺导管细胞的神经递质调节 功能。最近，已经获得了形态和生化数据 提示人颌下腺HSG-PA细胞系 导管起源，具有正常导管的几个重要特征 细胞，因此很有希望成为研究导管细胞的模型系统- 神经递质的特殊功能及其调节。我们的研究 到目前为止，已经证明在HSG-PA细胞中存在VIP受体， 偶联到腺酰环化酶，对于神经降压素和ATP，偶联到 磷脂酶C。其他初步证据表明激动剂-- K+和C1-通量的刺激增加，以响应一个或多个 这些物质和这些反应的变化通过渗透攻击，在 哪种细胞暴露在低渗介质中会导致戏剧性的 神经递质刺激的离子(K+)通量增加，而高渗 中等剂量可阻断神经递质刺激的流量。这项建议 重点介绍了神经递质对导管细胞离子转运的调节以及 用HSG-PA细胞系研究渗透压变化对这种调节的影响 作为一名模特。第一，血管活性肠肽、神经降压素和三磷酸腺苷对单价的调节 将对离子通量进行评估。跨细胞离子运动，研究于 使用小室，将测量激动剂诱导的短路变化 与放射性同位素示踪和离子置换相结合的电流 用于鉴定运输物种的实验。受体和非受体 细胞内信号通路的调节器将被用来关联 第二信使与离子通量的变化和相互作用。 放射性配基结合将被用来进一步表征受体 牵涉其中。调查的第二个领域集中在确定 介质渗透压变化调节离子传输的机制 神经递质的调节。在不连续的步骤中研究 细胞内信号传递过程(激动剂与受体结合；G蛋白 参与，第二信使生产，激活K+通量)将是 用来定义信号通路中的渗透点 挑战影响神经递质对K+通量的调节。加在一起，这些 研究有望极大地增加我们对 血管活性肠肽、神经降压素和三磷酸腺苷对唾液分泌过程的调节 导管细胞与细胞渗透环境中的角色扰动 通过这些神经递质调节运输，从而帮助 为评估改变在导管细胞中的作用奠定基础 不同外分泌疾病状态下的特殊功能及其调控。