Central Control of Pancreatic Islet Function

 描述（由申请人提供）：肥胖相关的2型糖尿病是一种全球流行的主要健康问题。该疾病的发作以功能性胰岛β细胞团不能满足代谢需求为标志，因此是胰岛素不足的状态。由此可见，保护和保存足够功能性胰岛细胞团的方法对2型糖尿病具有治疗潜力。关于营养素和激素对胰岛细胞功能的调节，我们已经知道很多了。然而，尽管160多年来已知中枢神经系统（CNS）对胰岛功能具有显著程度的控制，但CNS对胰岛β细胞的控制机制仍然模糊。事实上，中枢神经系统连接胰岛的精确区域是未知的。在本提案中，打算利用一个 新型伪狂犬病病毒载体（PRV）作为逆行跨突触神经元示踪剂，以准确地追踪体内胰岛和CNS特定区域之间的神经元联系。这将通过几种体内顺行追踪技术来补充，以完善PRV逆行追踪。Aim-1将使用逆行和顺行神经元追踪方法，以5µ m分辨率和3D显示小鼠CNS“脑-胰岛地形图”。这张地图将被详细描述，特别是揭示什么样的神经细胞 并利用新的顺行追踪技术来识别可以在该图中激活的特定神经元回路。在Aim-2中，将使用腺病毒载体的精确立体定位递送来操纵“脑-胰岛图”内的葡萄糖敏感神经元 从而改变下丘脑特定亚区域的葡萄糖激酶活性。同样，在Aim-3中，将采用类似的立体定位方法，但旨在特异性靶向特定的下丘脑胰岛素信号传导神经元，其中胰岛素受体和IRS-2基因功能将被操纵。然后，将评估连接到胰岛的CNS区域中的葡萄糖传感和/或胰岛素信号传导的改变是否会影响体内胰岛细胞功能，特别是关于β细胞质量、胰岛素和胰高血糖素分泌的控制。这将相对于代谢稳态和胰岛素敏感性进行测量，以便区分CNS对胰岛细胞功能的直接急性效应，而不是胰岛细胞次要作用的外周代谢效应。因此，新发现的“脑-胰岛图”将被验证为功能指南，并获得对胰岛细胞功能的CNS神经元控制的新机制见解。预计这项研究最终将转化为糖尿病/肥胖症的诺埃尔治疗方法。

 DESCRIPTION (provided by applicant): Obesity-linked type 2 diabetes is a major health problem of worldwide epidemic proportions. The onset of the disease is marked by failure of the functional pancreatic islet ß-cell mass to meet metabolic demand, and is thus an insulin insufficient state. It follows that a means to protect and preserve adequate functional ß-cell mass has therapeutic potential for type 2 diabetes. Much is known about nutrient and hormonal regulation of ß-cell function. However, despite it being known for more than 160 years that the central nervous system (CNS) has a significant degree of control over pancreatic islet functions, mechanisms of CNS control over pancreatic ß-cells remain vague. Indeed, the precise regions of the CNS that link to pancreatic islets are unknown. In this proposal it is intended to utilize a novel class of pseudorabies viral vectors (PRV) as retrograde transynaptic neuronal tracers to accurately track the neuronal link between pancreatic islets and specific regions of the CNS in vivo. This will be complemented by several in vivo anterograde-tracing techniques to refine the PRV retrograde tracing. Aim-1 will use both retrograde and anterograde neuronal tracking approaches to reveal a CNS `brain-to-islet topographical map' in mice, at a 5µm-resolution and in 3D. This map will be characterized in detail, particularly to unveil what kind of neuronal cells are within it and to utilize novel anterograde-tracking techniques to identify specific neuronal circuitries that can be activated within this map. In Aim-2 glucose-sensing neurons within the `brain-to-islet map' will be manipulated, using accurate stereotaxic delivery of adenoviral vectors that alter glucokinase activity in specific sub-regions of the hypothalamus. Likewise, in Aim-3, a similar stereotaxic approach will be taken, but aimed at specifically targeting particular hypothalamic insulin-signaling neurons, where insulin receptor and IRS-2 gene function will be manipulated. Then, it will be assessed whether alteration of glucose-sensing and/or insulin-signaling in regions of the CNS which link to pancreatic islets will affect islet cell function in ivo, particularly in regard to control of ß-cell mass, insulin and glucagon secretion. This will be measured relative to metabolic homeostasis and insulin sensitivity, so as to distinguish between direct acute effects of the CNS on islet cell function rather than peripheral metabolic effects to which islet cells act secondarily. Thus, the newly revealed `brain-to-islet map' will be validated as a functional guide, and novel mechanistic insight into CNS neuronal control of pancreatic islet cell functions gained. It is anticipated that this research will eventually translate into noel therapeutic approaches for the treatment of diabetes/obesity.