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(氧磷酸盐与糖酵解) 和线粒体燃料选择(葡萄糖/脂肪酸)，但相互作用和潜在机制没有 在脑部微循环中进行了检测。脑血管系统能量产生的研究有 在工作日进行，以方便实验室工作人员，相反， 当血糖水平和线粒体替代燃料水平波动时，啮齿动物的非活动禁食时间 广泛地。最近的论文强调了昼夜节律在疾病发生中的重要性，例如 用于中风和最佳化疗时机的选择。我们将提高对此的认识 利用我们实验室开发的创新方法和方法，在激动人心的、 首次确定大动脉和大动脉的线粒体和糖酵解动力学的新发现 小鼠衰老过程中的微血管(微血管、末梢小动脉、毛细血管、小静脉)。重要的是，我们制作了 意外发现大脑MVS中的纤维蛋白原水平在衰老过程中增加，可能是通过 循环外切体，而纤维蛋白原诱导氧化应激和进一步破坏紧张型 大脑内皮细胞的连接。我们推测线粒体功能障碍导致纤维蛋白原 脑MVS中ROS的积聚和产生导致小胶质细胞的激活和β-受体的积聚 淀粉样蛋白。与PAR-19-070相关：脑微循环，包括血脑屏障(BBB)，面对 在应对生理和营养状况的同时不断面临新陈代谢挑战，而生理和营养状况加剧了这一挑战 通过昼夜节律和衰老。对大脑MVS的关注是必要的，因为能量的不利变化 微循环中的产物促进认知障碍、中风、血管性痴呆和阿尔茨海默氏症 疾病(AD)，因为纤维蛋白原堆积导致β淀粉样蛋白堆积和小胶质细胞 激活--AD的特征。我们的研究在概念上是创新的，基于我们在 以及新技术的应用带来的技术创新。我们的假设是年龄--或时间-- 相关线粒体功能障碍是保护MVS和MVS潜在治疗的关键靶点 保护大脑免受神经损伤和认知障碍。我们有两个目标。目标1：澄清 衰老过程中脑微血管线粒体、糖酵解和细胞变化的机制。我们将：a) 利用在体多光子检测MVS和BBB状态的线粒体和血管特征 在4-6个月(幼龄)、12-14个月(中年)和18-24个月(老年)的小鼠身上进行成像；b)确定影响 衰老对糖酵解和OXPHOS、线粒体燃料选择以及MVS和动脉中有丝分裂酶的影响；c) 研究纤维蛋白原在衰老过程中促进MVS和动脉线粒体变化中的作用；以及d) 探索保护线粒体和脑循环不受衰老影响的治疗方法。目标2： 确定脑MVS中线粒体、糖酵解和细胞变化的机制 衰老过程中的昼夜循环。我们将：a)确定线粒体和微血管特征以及血脑屏障 小鼠在日常周期中的状态；b)确定对糖酵解和线粒体燃料OXPHOS的影响 选择，以及动脉和MVS中的mitoROS；c)阐明了MV中线粒体变化的机制， 动脉和微血管；以及d)探索改善MVS线粒体动力学的治疗方法 和动脉，维持微血管功能，保持血脑屏障状态。

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.