PARASYMPATHETIC DYSFUNCTION IN OBESITY: EFFECT OF CHOLESTEROL ON VAChT

肥胖引起的副交感功能障碍：胆固醇对 VAChT 的影响

• 批准号: 8497126
• 负责人: Yifan Li
• 金额: $ 40.88万
• 依托单位: UNIVERSITY OF SOUTH DAKOTA
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-07-10 至 2017-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8497126
• 关键词: Acetylcholine; Address; Affect; Area; Arrhythmia; Attenuated; Autonomic nervous system disorders; Bradycardia; Cardiac; Cardiovascular Diseases; Carrier Proteins; Cell Line; Cells; Cholesterol; Data; Diet; Exhibits; Fatty acid glycerol esters; Fiber; Functional disorder; Heart; Heart Atrium; Heart Rate; Hypertension; Mediating; Modeling; Mono-S; Mus; Myocardial; Myocardial Ischemia; Nervous System Physiology; Neurons; Neurotransmitters; Obese Mice; Obesity; Obesity associated cardiovascular disease; Parasympathetic Nervous System; Peripheral; Plasma; Play; Prevention; Proteins; Public Health; Recycling; Regulation; Research; Risk Factors; Role; Sampling; Signal Pathway; Synaptic Vesicles; System; Testing; Tissues; Ubiquitin; Ubiquitination; United States; acetylcholine transporter; cholinergic; cholinergic neuron; feeding; hypercholesterolemia; insight; novel; novel strategies; obesity treatment; overexpression; prevent; public health relevance; research study; response; trafficking; ubiquitin-protein ligase; uptake

DESCRIPTION (provided by applicant): Obesity is a serious public health issue in the United States 1 and worldwide 2 and is a major risk factor for hypertension, arrhythmia, myocardial ischemia, heart failure1, 3-6, and diabetes4, 7. In obesity, parasympathetic nervous system (PSNS) regulation of the heart is markedly attenuated 8-10, which may contribute to obesity-related arrhythmia and myocardial ischemia8, 11-13. To date, however, the mechanisms of the reduced PSNS function on the heart in obesity are still poorly understood. Acetylcholine (Ach) is a major neurotransmitter of PSNS. Vesicular acetylcholine transporters (VAChT) are responsible for Ach packaging In PSNS cholinergic terminals. High plasma cholesterol (hypercholesterolemia) affects neurons in the brain14-16 but its effect on the peripheral cholinergic system is unknown. Our recent study identified mono-ubiquitination is involved in VAChT recycling and Ach uptake activity. In high fat diet (HFD)-induced obese mice, VAChT ubiquitination is reduced, along with the attenuated PSNS regulation of the heart. This study is to test a central hypothesis that Attenuated PSNS action on the heart in obesity is related to the inhibitory effect of high cholesterol on the ubiquitination-mediated VAChT recycling, leading to the reduced VAChT level and function in synaptic vesicles and decreased Ach release in PSNS cholinergic terminals. Aim 1 will test whether the attenuated PSNS effect on the heart in HFD-induced obese mice involves reduced Ach release and VAChT expression at parasympathetic terminals in the heart. Mice fed a regular diet (RD) or HFD for 6 weeks will be used as an obesity model. Vagal stimulation (VS)-induced bradycardia and Ach release in atria, and VAChT protein levels and Ach uptake activity in synaptic vesicles from PSNS cardiac terminals will be examined. Aim 2 will elucidate whether high cholesterol plays a role in the PSNS cholinergic dysfunction in the heart. Mice fed RD, RD plus Statin, HFD, HFD plus Statin, RD plus 2% cholesterol and RD plus 2% cholesterol plus Statin will be used. Responses to VS and VAChT level and Ach uptake in the PSNS cardiac terminals will be examined and correlated with cholesterol levels. The direct effect of cholesterol on VAChT expression and Ach uptake will also be tested in a cholinergic cell line, SN56. Aim 3 will delineate whether high cholesterol inhibits the mono-ubiquitination-mediated VAChT recycling and thus function in the PSNS terminals. Correlation of plasma cholesterol levels with mono- ubiquitination and Ach uptake activity of VAChT will be analyzed in atria samples from the six groups in Aim 2; The direct inhibitory effect of cholesterol on VAChT mono-ubiquitination, recycling and activity will be tested using SN56 cells. Overall, results of this study will demonstrate that the negative effect of high cholesterol on the ubiquitination-mediated VAChT recycling contributes to the reduced PSNS cholinergic action on the heart in obesity. This novel concept may open a new area of research and may suggest novel strategies for prevention and treatments of obesity-related autonomic and cardiovascular disorders.

描述（由申请人提供）：肥胖在美国 1 和全世界 2 都是一个严重的公共卫生问题，并且是高血压、心律失常、心肌缺血、心力衰竭 1, 3-6 和糖尿病 4, 7 的主要危险因素。肥胖时，心脏的副交感神经系统 (PSNS) 调节显着减弱 8-10，这可能导致肥胖相关的心律失常 和心肌缺血8, 11-13。然而，迄今为止，肥胖患者心脏 PSNS 功能降低的机制仍知之甚少。 乙酰胆碱 (Ach) 是 PSNS 的主要神经递质。囊泡乙酰胆碱转运蛋白 (VAChT) 负责 PSNS 胆碱能终端中的 Ach 包装。高血浆胆固醇（高胆固醇血症）会影响大脑中的神经元14-16，但其对周围胆碱能系统的影响尚不清楚。我们最近的研究发现单泛素化参与 VAChT 回收和 Ach 摄取活动。在高脂饮食 (HFD) 诱导的肥胖小鼠中，VAChT 泛素化水平降低，同时 PSNS 对心脏的调节也减弱。 本研究旨在检验一个中心假设，即肥胖患者 PSNS 对心脏的作用减弱与高胆固醇对泛素化介导的 VAChT 循环的抑制作用有关，导致突触小泡中 VAChT 水平和功能降低，以及 PSNS 胆碱能末端 Ach 释放减少。目标 1 将测试 HFD 诱导的肥胖小鼠中 PSNS 对心脏的影响减弱是否涉及心脏副交感神经末梢 Ach 释放和 VAChT 表达的减少。喂养常规饮食 (RD) 或 HFD 6 周的小鼠将被用作肥胖模型。将检查迷走神经刺激 (VS) 诱导的心动过缓和心房 Ach 释放，以及 PSNS 心脏末梢突触小泡中 VAChT 蛋白水平和 Ach 摄取活性。目标 2 将阐明高胆固醇是否在心脏 PSNS 胆碱能功能障碍中发挥作用。将使用RD、RD加他汀类药物、HFD、HFD加他汀类药物、RD加2%胆固醇和RD加2%胆固醇加他汀类药物喂养的小鼠。将检查对 VS 和 VAChT 水平的反应以及 PSNS 心脏末梢的 Ach 摄取，并将其与胆固醇水平相关联。胆固醇对 VAChT 表达和 Ach 摄取的直接影响也将在胆碱能细胞系 SN56 中进行测试。目标 3 将描述高胆固醇是否会抑制单泛素化介导的 VAChT 循环，从而抑制 PSNS 终端的功能。将在目标 2 中的六组心房样本中分析血浆胆固醇水平与 VAChT 的单泛素化和 Ach 摄取活性的相关性；将使用 SN56 细胞测试胆固醇对 VAChT 单泛素化、回收和活性的直接抑制作用。 总的来说，这项研究的结果将证明，高胆固醇对泛素化介导的 VAChT 回收的负面影响导致肥胖患者 PSNS 对心脏的胆碱能作用降低。这一新概念可能会开辟一个新的研究领域，并可能提出预防和治疗肥胖相关自主神经和心血管疾病的新策略。