Hypothalmic glucose sensing and hypoglycemic counterregulation

描述（由申请人提供）：这是新研究者的RO 1申请。该项目的总体目标是识别受损的低血糖反调节的组成部分，以及识别和测试潜在的新靶点进行治疗干预。1型和晚期2型糖尿病患者的常见发现是葡萄糖感知受损、低血糖无意识和反调节受损。这些病理过程加剧了胰岛素诱导的低血糖发作的频率和严重程度，使低血糖成为糖尿病血糖管理中的限速步骤。本申请的初步结果表明，除了急性降低血糖水平外，胰岛素在大脑中具有主要的直接作用，以独立地调节葡萄糖感知和交感肾上腺对低血糖的反应。该提案的总体假设是，调节中枢神经系统下丘脑中的胰岛素敏感性治疗靶点可以改善实验动物对低血糖的认知和反调节反应。使用区域性下丘脑RT-PCR技术来鉴定关键基因和下丘脑基因表达的组合模式将有助于鉴定下丘脑葡萄糖感知受损和反调节受损的动物模型中的分子病理学。本研究计划的具体目标是：（1）分析胰岛素在中枢神经系统（CNS）中调节低血糖反调节反应的潜在作用;（2）确定胰岛素可通过调节葡萄糖转运蛋白和/或葡萄糖激酶来调节下丘脑葡萄糖感知的机制，并将这些胰岛素-（3）在中枢神经系统胰岛素作用增强或减弱的模型中，探讨胰岛素在急性低血糖时改变认知功能的作用，并区分认知反应和反调节反应;和（4）使用RT-PCR检测可独特归因于胰岛素诱导的复发性低血糖的局部下丘脑基因表达的模式，并将基因表达的改变与受损的葡萄糖感知和受损的低血糖反调节相关联。

DESCRIPTION (provided by applicant): This is a RO1 application by a new investigator. The overall goal of this project is to identify components of impaired hypoglycemic counterregulation as well as to identify and test potential new targets for therapeutic intervention. Common findings in patients with type 1 and advanced type 2 diabetes are impaired glucose sensing, hypoglycemia unawareness and impaired counterregulation. These pathological processes exacerbate the frequency and severity of insulin-induced hypoglycemic episodes making hypoglycemia the rate limiting step in the glycemic management of diabetes. Preliminary results in this application demonstrate that insulin, in addition to acutely lowering blood glucose levels, has a major direct effect in the brain to independently modulate both glucose sensing and the sympathoadrenal response to hypoglycemia. The overall hypothesis in this proposal is that modulation of insulin-sensitive therapeutic targets in the hypothalamus of the central nervous system can improve the cognitive and counterregulatory responses to hypoglycemia in experimental animals. The use of a regional hypothalamic RT-PCR technique to identify key genes and combined patterns of hypothalamic gene expression will help to identify molecular pathology in animal models of impaired hypothalamic glucose sensing and impaired counterregulation. The specific aims to be addressed in this research proposal are to: (1) dissect the potential role of insulin action in the central nervous system (CNS) in regulating the counterregulatory response to hypoglycemia; (2) determine the mechanisms by which insulin may regulate hypothalamic glucose sensing via regulation of glucose transporters and/or glucokinase and correlate these insulin-modulated changes in glucose sensing neurons with neuronal functional activity under conditions of hypoglycemia; (3) explore the role of insulin in altering cognitive function during acute hypoglycemia in models of increased or decreased CNS insulin action and differentiate the cognitive from the counterregulatory responses; and (4) examine the pattern of regional hypothalamic gene expression uniquely attributable to insulin-induced recurrent hypoglycemia with the use of RT-PCR and correlate alterations in gene expression with impaired glucose sensing and impaired hypoglycemic counterregulation.