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

项目摘要 这项提议的中心目标是阐明瘦素是如何转运到脑脊液中的。 和大脑在脉络丛(CHP)的门控，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，以及饱和的CHP转运如何促进瘦素抵抗 肥胖。能量消耗和进食的调节对动物的生存和维持能力至关重要 生理动态平衡。瘦素是脂肪细胞分泌的一种内分泌因子，参与调节 食物摄入量和体重。瘦素作用于大脑中的受体，发挥整体作用以减少 喂食，增加能量消耗，促进瘦肉型。瘦素必须进入大脑才能到达它的 感受器。在肥胖患者中，循环瘦素水平升高，但脑脊液与血清瘦素的比率降低， 瘦素在中枢给药而不是外周给药时会抑制食物的摄入。这表明不充分 脑脊液中瘦素的运输是肥胖发生的潜在因素。前期工作已完成 通过CHP上皮的血-脑脊液屏障作为关键途径的跨细胞反应 瘦素进入大脑。事实上，内吞受体低密度脂蛋白受体相关的局部缺失 CHP上皮细胞中的蛋白1(LRP1)在保持正常摄食的同时，减轻外周瘦素对摄食的抑制 中枢释放的瘦素引起的食物摄入量的减少。然而，它的实时动态 关于CHP跨细胞转运的提议，人们知之甚少。我建议将新的活体成像应用于 研究瘦素通过慢性幽门螺杆菌上皮细胞转运的技术及其获得途径和影响 清醒状态下腹侧被盖区(VTA)瘦素敏感型多巴胺能神经回路的研究 行为不端的老鼠。在目标1中，我将改进最近开发的工具，以实时可视化CHP中的瘦素跨细胞作用 时间(见初步数据)并定量评估LRP1缺失或过表达对瘦素的影响 从血液传输到脑脊液。瘦素一旦到达大脑，已知会与许多神经联系起来。 电路。VTA中的多巴胺能神经元编码食物的动机突显，通常被抑制 由瘦素引起，导致食物消费动力降低。然而，在肥胖症中，VTA调节失调 多巴胺能活动促进强迫性进食。在Aim 2中，我将扩展成像工具包以跟踪访问 同时记录单个VTA多巴胺能神经元的活动， 并严格评估CHP的瘦素细胞转运和VTA多巴胺能反应之间的相互作用 到瘦小和肥胖小鼠的可口食物。此外，我将确认LRP1是否在CHP上皮细胞中过表达 可以预防肥胖症的发展。这些研究将为我们提供对 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 以前所未有的精度发出信号，并提出治疗肥胖症和其他疾病的新方法 代谢紊乱。

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.