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）：肥胖是美国1和全球2的严重公共卫生问题，是高血压，心律失常，心肌缺血，心力衰竭，心力衰竭1、3-6和糖尿病的主要危险因素。4。和心肌缺血8，11-13。然而，迄今为止，肥胖症中降低的PSN功能降低的机制仍然鲜为人知。 乙酰胆碱（ACH）是PSN的主要神经递质。囊泡乙酰胆碱转运蛋白（VACHT）负责PSNS胆碱能末端的ACH包装。高血浆胆固醇（高胆固醇血症）会影响脑部14-16中的神经元，但其对外周胆碱能系统的影响尚不清楚。我们最近的研究确定了单泛素化涉及VACHT回收和ACH吸收活性。在高脂肪饮食（HFD）诱导的肥胖小鼠中，vacht泛素化降低，以及衰减的心脏调节。 这项研究是为了检验一个中心假设，即肥胖症中对PSNS对心脏的作用减弱与高胆固醇对泛素化介导的VACHT回收的抑制作用有关，从而导致VACHT水平降低和突触中的功能，并在PSNS胆碱能术中降低ACH释放。 AIM 1将测试HFD诱导的肥胖小鼠对心脏的衰减效果是否涉及心脏副交感神经末端的ACH释放和VACHT表达降低。喂养常规饮食（RD）或HFD 6周的小鼠将用作肥胖模型。将检查迷走神经刺激（VS）诱导的心房中的心动过缓和ACH释放，将检查来自PSNS心脏末端的突触囊泡中的VACHT蛋白水平和ACH摄取活性。 AIM 2将阐明高胆固醇是否在心脏的PSNS胆碱能功能障碍中起作用。小鼠Fed Rd，Rd Plus Statin，HFD，HFD Plus Statin，RD Plus 2％胆固醇和RD Plus 2％胆固醇加毒酚将使用他汀类药物。对VS和VACHT水平的反应以及PSNS心脏终末中的ACH吸收将与胆固醇水平进行检查并相关。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。 AIM 3将描绘高胆固醇是否抑制单泛素化介导的VACHT回收，从而在PSNS末端起作用。血浆胆固醇水平与AIM 2中六组的心房样本中分析了血浆胆固醇水平与vacht的单量化和吸收活性的相关性；胆固醇对VACHT单泛素化，回收和活性的直接抑制作用将使用SN56细胞进行测试。 总体而言，这项研究的结果将表明，高胆固醇对泛素化介导的VACHT回收的负面影响有助于降低肥胖症对心脏的PSNS胆碱能作用。这个新颖的概念可能会开放一个新的研究领域，并可能提出预防和治疗肥胖相关自主和心血管疾病的新型策略。