Effects on the brain microvasculature of age and circadian rhythm as risk factors for Alzheimer's disease

衰老和昼夜节律对能量产生有独立的影响（OXPHOS与糖酵解） 和线粒体的燃料选择（葡萄糖/脂肪酸），但相互作用和潜在的机制还没有 在大脑微循环中进行了检查。对脑血管能量产生的研究 在工作日进行，以方便实验室工作人员，这是，相反， 当葡萄糖水平和线粒体替代燃料水平波动时，啮齿动物的不活动，禁食时间 广泛地。最近的论文强调了昼夜节律对疾病发生的重要性， 中风和化疗的最佳时机的选择。我们将提高对此的认识 重要领域使用创新的方法和我们的实验室开发的方法，由令人兴奋的支持， 新的发现，以确定第一次线粒体和糖酵解动力学的大（动脉）， 微血管（MV，末端小动脉，毛细血管，微静脉）在小鼠衰老过程中的作用。重要的是， 出乎意料的发现是，大脑MV中的纤维蛋白原水平在衰老过程中增加，可能是通过 纤维蛋白原诱导氧化应激，并进一步破坏细胞的紧密结合。 脑内皮细胞的连接。我们推测线粒体功能障碍诱导纤维蛋白原 在脑MV中的积累和ROS产生导致小胶质细胞的活化和β-半乳糖苷酸的积累。 淀粉样蛋白与PAR-19-070的相关性：脑微循环，包括血脑屏障（BBB），面临 不断的代谢挑战，同时应对生理和营养状况，这是加剧 昼夜节律和衰老的影响。重点关注脑MV是有必要的，因为能量的不利变化 在微循环中产生促进认知障碍、中风、血管性痴呆和阿尔茨海默氏症 疾病（AD），并且因为纤维蛋白原积累引起β淀粉样蛋白积累和小胶质细胞增生， 激活-AD的标志。我们的研究是基于我们的新发现在概念上创新， 由于新技术的应用，技术上也有创新。我们的假设是年龄-或者时间- 相关的线粒体功能障碍是保护MV的潜在疗法的关键靶标， 防止神经损伤和认知障碍。我们有两个目标。目标1：阐明 衰老过程中脑MVs的线粒体、糖酵解和细胞变化机制。我们将：a） 使用体内多光子测定MV的线粒体和血管特征以及BBB状态 在4-6（年轻）、12-14（中年）和18 - 24（老年）月龄的小鼠中成像; B）确定作用 衰老对糖酵解和OXPHOS、线粒体燃料选择以及MV和动脉中的mitoROS的影响; c） 研究纤维蛋白原在老化期间促进MV和动脉的线粒体变化中的作用;以及d） 探索保护线粒体和脑循环对抗衰老的治疗方式。目标二： 确定线粒体，糖酵解和细胞变化的机制，在脑MV过程中 老化过程中的昼夜循环。我们将：a）确定线粒体和微血管特征以及BBB B）确定对糖酵解和OXPHOS（线粒体燃料）的影响 选择，和动脉和MV中的线粒体ROS; c）阐明涉及MV中线粒体变化的机制， 动脉和微血管;以及d）探索改善MV中线粒体动力学的治疗方法 和动脉，维持微血管功能，并保持BBB状态。

Aging and circadian/diurnal rhythm have independent effects on energy production (OXPHOS vs. glycolysis) and mitochondrial fuel choice (glucose/fatty acids), but interactions and underlying mechanisms have not been examined in the cerebral microcirculation. Studies on energy production of the cerebral vasculature have been performed during the working day for the convenience of laboratory workers, which is, contrariwise, the inactive, fasting time for rodents when glucose levels and levels of alternative fuels for mitochondria fluctuate widely. Recent papers have highlighted the importance of diurnal rhythm on disease occurrence such as strokes and for the selection of optimal timing of chemotherapy. We will improve the understanding of this important area using innovative methods and approaches developed by our laboratory, supported by exciting, novel findings, to ascertain for the first time mitochondrial and glycolytic dynamics of large (arteries) and microvessels (MVs, end arterioles, capillaries, venules) during aging in mice. Importantly, we made the unexpected finding that fibrinogen levels in brain MVs increase during aging, probably transported by circulating exosomes, and that fibrinogen induces oxidative stress and further disruption of tight junctions in brain endothelial cells. We postulate that mitochondrial dysfunction induced fibrinogen accumulation and ROS production in brain MVs leads to activation of microglia and accumulation of beta amyloid. Relevance to PAR-19-070: The brain microcirculation, including the blood-brain barrier (BBB), faces constant metabolic challenges while responding to physiological and nutritional status, which are exacerbated by diurnal rhythm and aging. A focus on cerebral MVs is warranted because adverse changes in energy production in the microcirculation promote cognitive impairment, strokes, vascular dementia, and Alzheimer’s disease (AD), and because fibrinogen accumulation causes beta amyloid accumulation and microglia activation—hallmarks of AD. Our studies are conceptually innovative based on our novel discoveries in and technically innovative due to application of new technologies. Our hypothesis is that age- or time- related mitochondrial dysfunction is a critical target for potential therapies to protect the MVs and brain against neurological damage and cognitive impairment. We have 2 aims. Aim 1: Elucidate mechanisms of mitochondrial, glycolytic, and cellular changes in brain MVs during aging. We will: a) determine mitochondrial and vascular characteristics of MVs and BBB status using in vivo multiphoton imaging in mice at 4–6 (young), 12–14 (middle age) and 18‒24 (old) months of age; b) determine the effects of aging on glycolysis and OXPHOS, mitochondrial fuel choice, and mitoROS in MVs and arteries; c) investigate the role of fibrinogen in promoting mitochondrial changes of MVs and arteries during aging; and d) explore treatment modalities for protecting mitochondria and the brain circulation against aging. Aim 2: Determine mechanisms of mitochondrial, glycolytic, and cellular changes in brain MVs during the diurnal cycle during aging. We will: a) determine mitochondrial and microvascular characteristics and BBB status in mice during the daily cycle; b) determine effects on glycolysis and OXPHOS, mitochondrial fuel choice, and mitoROS in arteries and MVs; c) elucidate mechanisms involved in mitochondrial changes in MV, arteries, and microvascular; and d) explore therapeutic approaches to improve mitochondrial dynamics in MVs and arteries, maintain microvascular function, and retain BBB status.