The role of innervation for hormone secretion in human islets

在理解朗格汉斯胰岛如何在活体内发挥作用方面存在着根本的差距，无论是在本地还是在 胰腺环境或移植治疗1型糖尿病后。关于胰岛功能的研究最多 都是在体外进行的，因此对胰岛神经支配的作用知之甚少 荷尔蒙分泌。我们研究的长期目标是了解胰岛的细胞生物学。 活体中的朗格汉斯。此特定应用程序的目标是确定角色 利用一种允许活体成像的新技术平台，神经在胰岛激素的分泌中发挥作用 移植后有血管和神经支配的胰岛。在这项新技术中，胰岛被移植到 前房，其功能是在操作后局部和系统地记录。 眼睛的神经输入。中心假设是，在小鼠的胰岛中，自主神经系统调节 通过副交感胆碱能纤维分泌胰岛素和通过交感去甲肾上腺素能分泌高血糖素 纤维，但对人类胰岛功能的这种神经支配及其在体内的影响是有限的。在此视图中，鼠标 胰岛严重依赖神经输入，而人类的胰岛几乎调节激素的分泌。 自主地。这项拟议的研究的基本原理是，结果将导致缺失， 基本知识的基本要素，没有这些要素，就不能理解人类胰岛的生物学。 因此，拟议的研究与美国国立卫生研究院的任务有关，该任务涉及到 关于生命系统的性质和行为的基本知识。在强劲的初步数据的指引下， 这一假设将通过追求三个具体目标来检验：1)确定神经支配中的物种差异 体外胰岛的模式；2)建立眼内胰岛移植物决定其自身神经支配的机制 模型；以及3)确定神经输入在体内葡萄糖稳态中的作用。在第一个目标下， 胰岛的神经支配模式和神经递质受体类型的分布 将利用免疫组织化学和成像技术在小鼠和人的胰岛中系统地检测 [Ca~(2+)]。在第二个目标下，将对人和小鼠眼内胰岛移植进行比较。 免疫组织化学染色模式和自主神经纤维的活体追踪。在第三个目标下， 小鼠和人胰岛移植物的局部胰岛细胞反应和葡萄糖稳态调节 通过激活瞳孔反射的副交感和交感成分来挑战 药物阻断，并通过选择性地消除神经输入。建议的工作具有创新性。 因为它利用了一种新的技术平台，首次允许在体内成像功能 被神经支配的人和老鼠的胰岛。这项拟议的研究具有重要意义，因为它有望推动 并扩展目前胰岛调节葡萄糖动态平衡的模型。

There is a fundamental gap in understanding how the islets of Langerhans function in vivo, either in the native environment in the pancreas or after transplantation to treat type 1 diabetes. Most studies on islet function have been performed in vitro, and as a consequence little is known about the role of innervation on islet hormone secretion. The long-term goal of our research is to understand the cell biology of islets of Langerhans in the living organism. The objective of this particular application is to determine the role innervation plays in the secretion of islet hormones using a new technological platform allowing in vivo imaging of vascularized and reinnervated islets after transplantation. In this new technology, islets are transplanted into the anterior chamber of the eye, and their function is recorded locally and systemically after manipulation of the eye's neural input. The central hypothesis is that in mouse islets the autonomic nervous system modulates insulin secretion via parasympathetic cholinergic fibers and glucagon secretion via sympathetic noradrenergic fibers, but that for human islet function this innervation and its in vivo influence is limited. In this view, mouse islets are heavily dependent on nervous input, whereas human islets regulate hormone secretion almost autonomously. The rationale for the proposed research is that the results will contribute a missing, fundamental element to basic knowledge, without which the biology of human islets cannot be understood. The proposed research is therefore relevant to the mission of the NIH that pertains to the pursuit of fundamental knowledge about the nature and behavior of living systems. Guided by strong preliminary data, this hypothesis will be tested by pursuing three specific aims: 1) Identify species differences in the innervation patterns of pancreatic islets in vitro; 2) Establish that intraocular islet grafts determine their own innervation pattern; and 3) Establish the role of neural input on glucose homeostasis in vivo. Under the first aim, the innervation patterns of islets and the neurotransmitter receptor profiles of the innervated endocrine cell types will be systematically examined in mouse and human islets using immunohistochemistry and imaging of intracellular [Ca2+]. Under the second aim, intraocular human and mouse islet grafts will be compared in terms of immunohistochemical staining patterns and in vivo tracing of autonomic nervous fibers. Under the third aim, local islet cell responses and regulation of glucose homeostasis by mouse and human islet grafts will be challenged by activating the parasympathetic and sympathetic components of the pupillary reflex, by pharmacological blockade, and by selective elimination of the neural input. The proposed work is innovative because it capitalizes on a new technological platform that allows for the first time in vivo imaging the function of innervated human and mouse islet. The proposed research is significant because it is expected to advance and expand current models of the regulation of glucose homeostasis by pancreatic islets.