Allostasis and Metabolic Resiliency in Older People

描述（由申请人提供）：由于身体能力下降和下丘脑-垂体-肾上腺（HPA）轴敏感性增加，老年人可能对环境压力源特别敏感，导致对日常挑战重复和延长的激素反应。这些反复的激素扰动强烈地促成了现在所谓的适应负荷，这反过来又排除了一系列原发性事件和继发性健康后果，如血脂异常、内脏过度肥胖和胰岛素抵抗。老年人对环境应激的高反应性和代谢弹性的研究很少，因此，本提案的目的是确定衰老过程中应激反应、脂肪代谢和胰岛素抵抗之间的关系。具体目的是：1)确定65岁及以上健康和非肥胖男性和女性对急性心理生理挑战的主观日常生活经历与皮质醇反应曲线之间的关系；2)确定皮质醇高反应性对同一老年样本中脂肪分解和胰岛素抵抗的几个功能指标的影响；3)确定皮质醇高反应性和胰岛素抵抗之间的关系在多大程度上受生长激素（GH）对心理生理挑战的反应以及IL-6水平和老年内脏脂肪的调节。我们计划一天使用一次混合法——重建方法(DRM)收集有关情感反应的定量信息日常生活经验可以贡献者或后果的HPA hyper-responsiveness衰老和将使用一个小说心理物理的挑战任务,模仿现实生活常见的环境情况下,如遇到当驾驶一辆汽车。自动心理物理测试（APT）是计算机化的一系列计时性能测量，包括简单反应时间、选择反应、视觉跟踪、静态和动态敏锐度以及信息处理。此外，我们将使用最先进的方法来量化内脏脂肪（CT扫描）和脂肪分解和胰岛素抵抗的指标（高胰岛素-正糖钳与示踪剂输注，用于测定肝糖生成和外周脂肪分解），以确定对常见日常挑战的负面反应相关的健康和功能后果。

DESCRIPTION (provided by applicant): Older people may be especially sensitive to environmental stressors due to diminished physical capabilities and an increased hypothalamo-pituitary-adrenal (HPA) axis sensitivity, resulting in repeated and prolonged hormonal responses to common day challenges. These repeated hormonal perturbations contribute strongly to what is now termed the allostatic load, which, in turn, precludes a cascade of primary events and secondary health consequences, such as dyslipidemia, excess visceral adiposity, and insulin resistance. Rarely is hyper-responsiveness to environmental stress and metabolic resiliency studied in older people and so, the purpose of this proposal is to determine the relation between stress response, fat metabolism, and insulin resistance in aging. Specific aims are: 1) to determine the association between subjective daily life experiences and the cortisol response curve to an acute psychophysical challenge in healthy and non-obese men and women 65 years of age and older; 2) to determine the effect of cortisol hyper-responsiveness on several functional indicators of lipolysis and insulin resistance in this same older sample; and 3) to determine the degree to which the relation between cortisol hyper-responsiveness and insulin resistance is modulated by growth hormone (GH) response to the psychophysical challenge and by levels of IL-6 and visceral adiposity in older age. We plan to use a recently-published hybrid method - the Day Reconstruction Method (DRM) - for gathering quantitative information about affective responses to daily life experiences that may be contributors to or consequences of a HPA hyper-responsiveness in aging and will use a novel psychophysical challenge with tasks that mimic common real life environmental situations, such as those encountered when driving an automobile. The automated psychophysical test (APT) is a computerized series of timed performance measures of simple reaction time, choice reaction, visual tracking, static and dynamic acuity, and information processing. In addition, we will use state-of-the-art methods for the quantification of visceral adiposity (CT scan) and the indicators of lipolysis and insulin resistance (the hyperinsulinemic-euglycemic clamp with tracer infusions for determination of hepatic glucose production and peripheral lipolysis) in order to determine the health and functional consequences associated with a negative response to common daily challenges.