Gating of Leptin Transport into the Cerebrospinal Fluid at the Choroid Plexus

瘦素转运至脉络丛脑脊液的门控

• 批准号: 10598456
• 负责人: Peter Nikolaevich Kalugin
• 金额: $ 3.96万
• 依托单位: HARVARD MEDICAL SCHOOL
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-04-01 至 2026-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10598456
• 关键词: Acute; Adipocytes; Adipose tissue; Adult; Animals; Apical; Area; Binge Eating; Blood; Blood - brain barrier anatomy; Blood capillaries; Body Weight; Brain; Calcium; Central Nervous System; Cerebrospinal Fluid; Choroid Plexus Epithelium; Critical Pathways; Cues; Data; Disease; Dopamine; Eating; Endocrine; Endothelium; Energy Metabolism; Epithelial Cells; Epithelium; Exhibits; Fasting; Fatty acid glycerol esters; Feeding behaviors; Food; Food Intake Regulation; Genetic Polymorphism; Goals; High Fat Diet; Homeostasis; Hormones; Human; Image; Imaging Techniques; Impairment; Individual; Infusion procedures; Insulin Resistance; Knock-out; LDL-Receptor Related Protein 1; Label; Leptin; Leptin resistance; Lipoprotein Receptor; Liquid substance; Low Density Lipoprotein Receptor; Measures; Mediating; Metabolic; Metabolic Diseases; Methods; Molecular; Motivation; Mus; Neurons; Neurosecretory Systems; Obese Mice; Obesity; Pathway interactions; Peripheral; Phenotype; Plasma; Prediabetes syndrome; Process; Proteins; Regulation; Rewards; Role; Satiation; Serum; Signal Transduction; Structure of choroid plexus; Surface; Testing; Thinness; Time; Tropism; Ventral Tegmental Area; Viral Vector; Visualization; Wild Type Mouse; Work; awake; blood cerebrospinal fluid barrier; calcium indicator; design; dopaminergic neuron; experimental study; feeding; food consumption; gene therapy; glucose tolerance; in vivo; in vivo imaging; insight; insulin tolerance; median eminence; monolayer; neural; neural circuit; novel; novel therapeutic intervention; obesity development; obesity treatment; overexpression; receptor; response; tool; transcytosis; two-photon

Project Summary The central goal of this proposal is to elucidate how leptin transport into the cerebrospinal fluid (CSF) and brain is gated at the choroid plexus (ChP), how such gating influences the action of leptin on reward- related dopaminergic neurons, and how saturated ChP transport may contribute to leptin resistance in obesity. Regulation of energy expenditure and feeding are crucial to an animal’s ability to survive and maintain physiological homeostasis. Leptin is an endocrine factor secreted by adipocytes that participates in the regulation of food intake and body weight. Acting on receptors in the brain, leptin exerts an overall effect to decrease feeding, increase energy expenditure, and promote a lean phenotype. Leptin must enter the brain to reach its receptors. In obesity, circulating leptin levels are elevated, but the ratio of CSF to serum leptin is reduced, and leptin suppresses food intake when administered centrally but not peripherally. This suggests insufficient transport of leptin into the CSF as a potential contributor to the development of obesity. Preliminary work has implicated transcytosis through the blood-cerebrospinal fluid barrier of the ChP epithelium as a critical pathway of leptin entry into the brain. In fact, local deletion of endocytic receptor low density lipoprotein receptor-related protein 1 (LRP1) in the ChP epithelium impairs feeding suppression by peripheral leptin while keeping intact the decrease in food intake in response to centrally delivered leptin. However, the real time dynamics of this proposed transcytotic transport at the ChP are poorly understood. I propose to apply novel in vivo imaging techniques to study leptin transcytosis through the ChP epithelium as well as its access to and effects on leptin-sensitive dopaminergic circuitry in the ventral tegmental area (VTA) in real time in awake, behaving mice. In Aim 1, I will refine recently developed tools to visualize leptin transcytosis at the ChP in real time (see preliminary data) and quantitatively assess the effects of LRP1 deletion or overexpression on leptin transport from the blood into the CSF. Once it reaches the brain, leptin is known to engage a number of neural circuits. Dopaminergic neurons in the VTA encode the motivational salience of food and are normally inhibited by leptin, leading to reduced motivation for food consumption. In obesity, however, dysregulated VTA dopaminergic activity promotes compulsive eating. In Aim 2, I will extend the imaging toolkit to track the access of leptin to the VTA parenchyma in parallel with recording the activity of individual VTA dopaminergic neurons, and rigorously assess the interplay between leptin transcytosis at the ChP and the VTA dopaminergic responses to palatable food in lean and obese mice. Additionally, I will confirm if LRP1 overexpression in the ChP epithelium could be protective against the development of obesity. These studies will provide novel insights into the pathways and mechanisms of leptin entry into the brain, assess the dynamics and downstream effects of leptin signaling with unprecedented precision, and propose new therapeutic approaches for obesity and other metabolic disorders.

项目概要 该提案的中心目标是阐明瘦素如何转运到脑脊液 (CSF) 中 大脑在脉络丛（ChP）处被门控，这种门控如何影响瘦素对奖赏的作用- 相关的多巴胺能神经元，以及饱和 ChP 运输如何导致瘦素抵抗 能量消耗和喂养的调节对于动物的生存和维持能力至关重要。 瘦素是脂肪细胞分泌的一种内分泌因子，参与调节。 瘦素作用于大脑中的受体，发挥总体作用来减少食物摄入量和体重。 喂养、增加能量消耗并促进瘦素表型。瘦素必须进入大脑才能达到其作用。 在肥胖症中，循环瘦素水平升高，但脑脊液与血清瘦素的比率降低，并且 瘦素在中枢而非外周给药时会抑制食物摄入，这表明瘦素不足。 瘦素转运至脑脊液是导致肥胖的潜在因素。 涉及通过 ChP 上皮血脑脊液屏障的转胞吞作用作为关键途径 瘦素进入大脑的过程实际上与内吞受体低密度脂蛋白受体的局部缺失有关。 ChP 上皮中的蛋白 1 (LRP1) 会损害外周瘦素的摄食抑制，同时保持完整的瘦素 然而，集中传递的瘦素导致食物摄入量减少，但这种情况的实时动态。 人们对 ChP 的转细胞转运知之甚少，我建议应用新颖的体内成像。 研究瘦素通过 ChP 上皮的转胞吞作用及其进入和影响的技术 清醒时实时观察腹侧被盖区（VTA）瘦素敏感的多巴胺能回路， 在目标 1 中，我将改进最近开发的工具，以真实地观察 ChP 中的瘦素转胞吞作用。 时间（参见初步数据）并定量评估 LRP1 缺失或过度表达对瘦素的影响 瘦素从血液运输到脑脊液后，会参与许多神经系统。 VTA 中的多巴胺能神经元编码食物的动机显着性，并且通常受到抑制。 然而，在肥胖症中，VTA 失调。 多巴胺能活动促进强迫性饮食 在目标 2 中，我将扩展成像工具包来跟踪访问。 瘦素到 VTA 实质的同时记录单个 VTA 多巴胺能神经元的活动， 并严格评估 ChP 的瘦素转胞吞作用与 VTA 多巴胺能反应之间的相互作用 此外，我将确认 ChP 上皮细胞中 LRP1 是否过度表达。 这些研究将为肥胖的发展提供新的见解。 瘦素进入大脑的途径和机制，评估瘦素的动力学和下游效应 以前所未有的精确度发出信号，并提出肥胖和其他疾病的新治疗方法 代谢紊乱。