Exploring the involvement of Na pump inhibitor marinobufagenin in the interactions between age-associated vascular and neurodegenerative processes in cognitive impairment and Alzheimer's disease

探索Na泵抑制剂marinobufagenin在认知障碍和阿尔茨海默病中与年龄相关的血管和神经退行性过程之间的相互作用中的作用

• 批准号: 10688863
• 负责人: Olga V Fedorova
• 金额: $ 39.21万
• 依托单位: NATIONAL INSTITUTE ON AGING
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10688863
• 关键词: Age; Aging; Alzheimer' s Disease; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Animal Model; Animals; Antihypertensive Agents; Anxiety; Attention; Auditory; Blood Pressure; Blood Vessels; Brain; Cardiovascular Diseases; Cardiovascular system; Cerebrovascular Circulation; Cerebrovascular Disorders; Control Animal; Dahl Hypertensive Rats; Data; Dementia; Development; Diet; Echocardiography; Elderly; Exhibits; Functional disorder; Hippocampus (Brain); Histocytochemistry; Human; Hypertension; Impaired cognition; Impulsivity; Inflammatory; Intervention; Light; Lisinopril; MRI Scans; Magnetic Resonance Imaging; Measures; Memory; Memory Loss; Microscopy; Microvascular Dysfunction; Modeling; N-acetylaspartate; Na(+)-K(+)-Exchanging ATPase; Nerve Degeneration; Neurons; Performance; Perfusion; Pharmacology; Physiologic pulse; Plethysmography; Prevention; Process; Profibrotic signal; Rattus; Risk Factors; Role; Serum; Sodium Chloride; Steroids; Structure; Tail; Testing; Translating; Travel; Urine; Vascular Dementia; Vascular blood supply; Visual; Water; age related; antifibrotic treatment; arterial stiffness; blood pressure elevation; brain magnetic resonance imaging; cerebral artery; cerebral hypoperfusion; cognitive function; cognitive performance; density; distraction; experimental study; hemodynamics; hypertensive; improved; inflammatory marker; inhibitor; male; marinobufagenin; morris water maze; neuron loss; novel; predictive marker; premature; rate of change; salt intake; salt sensitive; therapeutic target; trend

Experiment 1. Dahl-S rat model of age-associated vascular dementia Central arterial stiffness (CAS) is associated with elevated arterial blood pressure (BP) and is likely associated with stiffening of cerebral artery walls, with attendant cerebral hypoperfusion, neuronal density loss and cognitive decline. Dahl salt-sensitive (Dahl-S) rats exhibit age-associated hypertension and memory loss, even on a normal salt intake. We sought to explore whether central arterial pulse wave velocity (PWV), a marker of CAS, is associated with hippocampal cerebral blood flow (CBF) and neuronal density in hypertensive Dahl-S rats. We measured systolic BP (by tail-cuff plethysmography), aortic PWV (by echocardiography) and CBF and N-acetyl aspartate (NAA) (by magnetic resonance imaging) in twelve 6 months old male Dahl-S rats. We have demonstrated that greater PWV was significantly associated with lower CBF and lower NAA concentration in the hippocampus, supporting a role of CAS in cerebrovascular dysfunction and decline in cognitive performance with aging. These findings implicate increased CAS in cerebral hypoperfusion and loss of neuronal density and function in the Dahl-S model of age-associated cardiovascular dysfunction. Experiment 2. Effect of an ACE inhibitor in the Dahl-S rat model of age-associated vascular dementia A premature increase in aortic stiffening and BP, accompanied by spatial cognitive impairment, occur in Dahl salt-sensitive rats (Dahl-S) on a normal salt intake with advancing age. Because a novel pro-hypertensive and pro-fibrotic steroid, marinobufagenin (MBG), is implicated in BP increases in Dahl-S, we hypothesized that the changes in the levels of the pro-fibrotic factors, including MBG and angiotensin II, which stimulates MBG, will cause the arterial wall stiffening, which will lead to the structural changes in the cerebral arteries and neurons following by cognitive decline. We posited that pharmacologic interventions targeting age-dependent pro-fibrotic processes within the arterial wall to reduce central arterial stiffness, will ameliorate brain microvascular disease, cognitive impairment and dementia. Dahl-S (n=20) male rats were fed a normal salt diet for 12 months; 10 of them were continuously treated with an ACE inhibitor Lisinopril (15 mg/kg/day) administered through their water for 6 months, and 10 Dahl-S rats remained on regular water as a control (2 non-treated control animals died before the end of the experiment due to hypertension). Systolic BP (SBP), PWV, urine MBG, brain MRI scans, open field and attention tests (Fig. 1) were performed at 6 (baseline), 9 and 12 months, while Morris water maze (MWM) test and brain histochemistry were performed at 12-mo. We demonstrated that (i) greater PWV, a marker for CAS, was associated with a decreased hippocampal perfusion and a decreased neuronal mass (NAA). Higher hippocampal perfusion was associates with the lower anxiety level. This finding suggests that central arterial stiffness may be a potential therapeutic target for the prevention and treatment of dementia. (ii) Next, we demonstrated that Lisinopril treatment was associated with a decrease in PWV and SBP, and that MBG level was stable for the duration of the study in the treated rats whereas control animals exhibited increase in MBG and higher SBP and PWV. (iii) In hypertensive Dahl-S rats, Lisinopril treatment improved spatial hippocampal memory, which was associated with a decrease of distance traveled to find a hidden platform in Morris water maze and with a better path efficiency vs. non-treated controls. (iv) Preliminary results in attention test suggest that Dahl-S rats treated with Lisinopril for 6 months demonstrated increased attention during a challenge with auditory and visual distractions (p=0.04). Further analysis will be done to assess impulsivity and compulsivity in this attention test. (v) In addition, we found, that Lisinopril-treated animals demonstrates stabilization of hippocampal CBF and NAA (brain MRI data) while untreated animals exhibited trend to decline of these values with aging. Increased performance for treated animals in MWM points to spatial hippocampal memory benefits of treatment that support trends seen for hippocampal CBF and NAA. These findings are consistent with the preliminary brain vessels density histochemical data, obtained by a green light sheet microscopy. Dahl-S rats treated with Lisinopril, exhibited an increase in blood vessel density vs. non-treated controls, which can be translated that a higher blood supply to the brain is resulted after anti-hypertensive and anti-fibrotic treatment.

实验1.Dahl-S大鼠年龄相关性血管性痴呆模型 中央动脉硬化(CAS)与动脉血压(BP)升高有关，可能与脑动脉壁僵硬有关，并伴随着脑低灌流、神经元密度丧失和认知能力下降。Dahl盐敏感(Dahl-S)大鼠表现出与年龄相关的高血压和记忆力丧失，即使在正常的盐摄入量下也是如此。本研究旨在探讨高血压Dahl-S大鼠中央动脉脉搏波速度是否与海马区脑血流量和神经元密度有关。 本文报道了12只6月龄雄性Dahl-S大鼠的收缩压(尾袖体积描记法)、主动脉PWV(超声心动图)、脑血流量和N-乙酰天门冬氨酸(NAA)的测量结果。我们已经证明，较大的PWV与较低的CBF和较低的海马区NAA浓度显著相关，支持CAS在脑血管功能障碍和认知能力随年龄增长而下降的过程中所起的作用。 这些发现表明，在Dahl-S年龄相关性心血管功能障碍模型中，CAS增加导致脑灌流不足和神经元密度和功能丧失。 实验2.血管紧张素转换酶抑制剂对Dahl-S大鼠年龄相关性血管性痴呆模型的影响 随着年龄的增长，正常盐摄入量的Dahl盐敏感大鼠(Dahl-S)出现主动脉硬化和血压过早增加，并伴有空间认知障碍。由于一种新的促高血压和促纤维化的类固醇激素马利诺蟾毒配基与Dahl-S的血压升高有关，我们假设促纤维化因子水平的变化，包括MBG和刺激MBG的血管紧张素II，将导致动脉壁僵硬，从而导致脑动脉和神经元的结构变化，进而导致认知能力下降。我们假设，针对动脉壁内与年龄相关的促纤维化过程的药物干预可以减少中央动脉僵硬，将改善脑微血管疾病、认知障碍和痴呆。 Dahl-S雄性大鼠20只，给予正常食盐喂养12个月，其中10只给予血管紧张素转换酶抑制剂赖诺普利(15 mg/kg/d)灌胃6个月，另10只Dahl-S大鼠继续饮水作为对照(2只未治疗的对照组动物因高血压在实验结束前死亡)。分别于6个月(基线)、9个月和12个月进行收缩压(SBP)、脉搏血流量(PWV)、尿MBG、脑MRI扫描、开阔视野和注意力试验(图1)，12个月进行Morris水迷宫(MWM)试验和脑组织化学检查。 我们证明：(1)CAS的标志物PWV越大，海马灌注量越低，神经细胞质量(NAA)越小。较高的海马区血流灌注与较低的焦虑水平相关。这一发现表明，中央动脉僵硬可能是预防和治疗痴呆症的潜在治疗靶点。(Ii)接下来，我们证明，赖诺普利治疗与PWV和SBP降低有关，在研究期间，治疗组大鼠的MBG水平保持稳定，而对照组大鼠的MBG增加，SBP和PWV升高。(Iii)在高血压Dahl-S大鼠中，赖诺普利治疗改善了空间海马区记忆，这与减少在Morris水迷宫中寻找隐藏平台的距离有关，并具有比未治疗对照组更好的路径效率。(4)注意力测试的初步结果表明，给予赖诺普利6个月的Dahl-S大鼠在听觉和视觉分心的刺激下表现出更多的注意力(p=0.04)。在这次注意力测试中，将进行进一步的分析来评估冲动和强迫性。(V)此外，我们发现，赖诺普利治疗的动物表现出海马区CBF和NAA(脑MRI数据)的稳定，而未治疗的动物随着年龄的增长，这些值呈现下降的趋势。治疗动物在MWM中表现的改善表明，治疗对海马区空间记忆的好处支持了海马区CBF和NAA的趋势。 这些发现与绿光显微镜获得的初步脑血管密度组织化学数据是一致的。用赖诺普利治疗的Dahl-S大鼠与未治疗的对照组相比，血管密度增加，这可以解释为抗高血压和抗纤维化治疗后脑组织的血液供应增加。