Institut für Neuro- und Verhaltensbiologie, Universität Münster, Badestr. 9, 48149 Münster, Germany.
Institut für Neuro- und Verhaltensbiologie, Universität Münster, Badestr. 9, 48149 Münster, Germany.
Neurobiol Dis. 2017 Nov;107:15-31. doi: 10.1016/j.nbd.2017.02.008. Epub 2017 Feb 24.
The nervous system in higher vertebrates is separated from the circulation by a layer of specialized endothelial cells. It protects the sensitive neurons from harmful blood-derived substances, high and fluctuating ion concentrations, xenobiotics or even pathogens. To this end, the brain endothelial cells and their interlinking tight junctions build an efficient diffusion barrier. A structurally analogous diffusion barrier exists in insects, where glial cell layers separate the hemolymph from the neural cells. Both types of diffusion barriers, of course, also prevent influx of metabolites from the circulation. Because neuronal function consumes vast amounts of energy and necessitates influx of diverse substrates and metabolites, tightly regulated transport systems must ensure a constant metabolite supply. Here, we review the current knowledge about transport systems that carry key metabolites, amino acids, lipids and carbohydrates into the vertebrate and Drosophila brain and how this transport is regulated. Blood-brain and hemolymph-brain transport functions are conserved and we can thus use a simple, genetically accessible model system to learn more about features and dynamics of metabolite transport into the brain.
高等脊椎动物的神经系统通过一层特殊的内皮细胞与循环系统分开。它保护敏感的神经元免受有害的血液衍生物质、高浓度和波动的离子、外来物质甚至病原体的侵害。为此，脑内皮细胞及其相互连接的紧密连接形成了有效的扩散屏障。在昆虫中也存在结构类似的扩散屏障，其中神经胶质细胞层将血淋巴与神经细胞隔开。这两种类型的扩散屏障当然也阻止了代谢物从循环中流入。由于神经元功能消耗大量能量，并需要多种底物和代谢物的流入，因此必须有严格调控的运输系统来确保代谢物的持续供应。在这里，我们回顾了有关将关键代谢物、氨基酸、脂质和碳水化合物运入脊椎动物和果蝇大脑的运输系统的最新知识，以及这种运输是如何被调节的。血脑和血淋巴脑运输功能是保守的，因此我们可以使用简单的、遗传上可及的模式系统来了解更多关于代谢物进入大脑的运输的特征和动态。
