Determining if Reduced Insulin Response in the Brain is Linked to Cognitive Loss

项目摘要 随着人们年龄的增长，他们患痴呆症的风险增加。对于II型糖尿病患者， 糖尿病事实上，患有II型糖尿病的人患痴呆症的可能性是其他人的两倍多。 通过阿尔茨海默病（AD）、血管性认知障碍（CVI）或痴呆的发展， 将军对AD患者大脑的检查也揭示了这种相关性，因为大多数AD患者的大脑 在海马体中显示胰岛素抵抗，即使在临床上没有诊断出患有胰岛素抵抗的患者中， II型糖尿病这种大脑形式的胰岛素抵抗被称为III型糖尿病。 在以前的研究中，我们利用已知的功能丧失来检测早老素活性降低的影响。 果蝇早老素（PSN）突变。我们发现PSN活性降低的果蝇（PSN-HETS）显示出 在经典的求偶学习和记忆范例中，年龄发作的学习和记忆丧失。在最近几 对PSN-HET脑的研究发现，随着年龄的增长，它们会产生脑胰岛素抗性。我们发现 当psn-het果蝇是年轻的（成年的第5天）并且显示正常的认知时，它们的大脑显示 增加胰岛素信号传导和增加对胰岛素刺激的敏感性。旧的psn-het脑（第30天） 成年期），表现出学习和记忆的丧失，不能对胰岛素刺激作出反应。我们假设 老年PSN-HETS脑中胰岛素抵抗的建立导致所显示的认知缺陷 通过这个模型。在本建议的第一个目标中，我们将确定psn突变是否与家族性阿尔茨海默病有关。 疾病（FAD）也会导致大脑中胰岛素信号的改变、大脑胰岛素抵抗和年龄发作 认知丧失然后，我们将探索大脑中胰岛素信号的减少是否可以挽救 脑胰岛素抵抗和认知丧失。在本提案的第二个目标中，我们将确定PSN是否 突变导致外周胰岛素信号传导和外周胰岛素抗性的改变。这些研究将 确定PSN活性的丧失或改变是否优先诱导脑中的胰岛素抗性。我们还将 测试已知诱导果蝇外周胰岛素抵抗的治疗是否也会导致 大脑胰岛素抵抗和认知缺陷。这些研究将使用对照果蝇、psn-hets和 FAD突变杂合的苍蝇，允许检查饮食和减少的PSN的相互作用 活动这些研究将探索PSN活性的降低或改变对胰岛素信号传导的作用 以及胰岛素抵抗在大脑中的建立，以及这是否会导致认知障碍。 这些研究也将为探索痴呆症由于脑胰岛素的发展提供一个有用的模型 抵抗一般。

Project Summary As people age, their risk for developing dementia increases. This risk is enhanced for those with type II diabetes. In fact, individuals with type II diabetes are more than twice as likely to suffer from dementia, either through the development of Alzheimers disease (AD), Vascular cognitive impairment (CVI) or dementia in general. Examination of brains from AD patients also reveals this correlation as most brains from AD patients display insulin resistance in the hippocampus, even in patients that have not been clinically diagnoses with type II diabetes. This brain form of insulin resistance is referred to as type III diabetes. In previous studies we examined the effect of reduced presenilin activity utilizing known loss of function mutations of Drosophila presenilin (psn). We found that flies with reduced psn activity (psn-hets) displayed an age-onset loss-of-learning and memory in the classic courtship learning and memory paradigm. In more recent studies of the psn-het brains we have found that they develop brain insulin resistance with age. We find that when the psn-het flies are young (day 5 of adulthood) and display normal cognition, their brains display increased insulin signaling and increased sensitivity to insulin stimulation. Old psn-het brains (day 30 of adulthood) that display loss of learning and memory fail to respond to insulin stimulation. We hypothesize that the establishment of insulin resistance in the brains of the old psn-hets causes the cognitive deficits displayed by this model. In the first aim of this proposal we will determine if psn mutations linked to familial Alzheimers disease (FAD) also lead to altered insulin signaling in the brain, brain insulin resistance and age onset cognitive loss. We will then explore if the reduction of insulin signaling in the brain can rescue the formation of brain insulin resistance and cognitive loss. In the second aim of this proposal we will determine if psn mutations lead to alterations in peripheral insulin signaling and peripheral insulin resistance. These studies will determine if loss or alteration of psn activity preferentially induce insulin resistance in the brain. We will also test if treatments that are known to induce the development of peripheral insulin resistance in flies also cause brain insulin-resistance and cognitive deficits. These studies will be performed with control flies, psn-hets and flies heterozygous for FAD mutations, allowing for an examination of the interaction of diet and reduced psn activity. These studies will explore the role that reduction of, or alteration in psn activity has on insulin signaling and the establishment of insulin resistance in the brain and whether this can cause cognitive impairment. These studies will also provide a useful model to explore the dementia due to the development of brain insulin resistance in general.