Department of Anatomy & Neuroscience, Faculty of Medicine, Nara Medical University, 840 Shijo-cho, Kashihara, Nara ,634-8521, Japan.
Department of Anatomy & Neuroscience, Faculty of Medicine, Nara Medical University, 840 Shijo-cho, Kashihara, Nara ,634-8521, Japan.
Neurochem Int. 2019 Sep;128:135-142. doi: 10.1016/j.neuint.2019.04.007. Epub 2019 Apr 16.
The arcuate nucleus (Arc) integrates circulating hormonal and metabolic signals to control energy expenditure and intake. One of the most important routes that enables the Arc to sense circulating molecules is through the median eminence (ME), which lacks a typical blood-brain barrier. However, the mechanism by which circulating molecules reach the Arc neurons remains unclear. This review focuses on what is known to date regarding the special structure and permeability of the ME vasculature and active transport of circulating molecules from the ME to the Arc. Recent studies have demonstrated that the ME displays angiogenic behavior that is expected to provide high vascular permeability. Parenchymal diffusion of circulating molecules from the ME vasculature is size-dependent, and tanycytes actively transport circulating molecules from the ME to the Arc. Finally, we highlight structural plasticity of the Arc and ME as playing an important role in maintaining energy balance homeostasis.
弓状核（Arc）整合循环激素和代谢信号，以控制能量消耗和摄入。使 Arc 能够感知循环分子的最重要途径之一是通过正中隆起（ME），ME 缺乏典型的血脑屏障。然而，循环分子到达 Arc 神经元的机制尚不清楚。本综述重点介绍了迄今为止关于 ME 血管的特殊结构和通透性以及循环分子从 ME 向 Arc 的主动转运的已知内容。最近的研究表明，ME 表现出血管生成行为，预计会提供高血管通透性。循环分子从 ME 血管的实质扩散是大小依赖性的，并且 tanycytes 从 ME 主动转运循环分子到 Arc。最后，我们强调了 Arc 和 ME 的结构可塑性在维持能量平衡稳态中起着重要作用。
