AS THE COMMAND centre of the human body, the brain requires the best protection biology can supply. The hard, bony casing of the skull helps to shield the organ from threats outside the body. But dangers lie within, too. Blood can contain toxins and pathogens which would wreak havoc(造成严重破坏) in the brain’s delicate environment. Keeping such vandals out is the job of the blood-brain barrier, a tightly packed network of cells coating the interior surfaces of blood vessels leading to the brain.(阻止这些破坏分子进入，正是血脑屏障的职责——它是一层紧密排列的细胞网络，覆盖在通往大脑的血管内表面。)
作为人体的指挥中心，大脑需要生物学所能提供的最佳保护。坚硬多骨的颅骨外壳有助于保护这一器官免受体外威胁。但危险也存在于体内。血液中可能含有毒素和病原体，它们会在人脑脆弱的环境中造成严重破坏。阻止这些“破坏分子”进入大脑，正是血脑屏障的职责——这是一层紧密排列的细胞网络，覆盖在通往大脑的血管内表面。
In a new study, published in Cell on November 11th, a team led by Andrew Yang, a neuroscientist at the Gladstone Institute of Neurological Disease(格拉德斯通神经疾病研究所) in San Francisco, has shown that the blood-brain barrier is surprisingly sophisticated(复杂精密的). By cataloguing the proteins that were allowed through the barrier in mice, the researchers found that it plays a far more active role in brain health than previously thought.(通过记录小鼠体内被允许穿过屏障的蛋白质，研究人员发现，它在维持大脑健康方面发挥的作用远比此前认为的更为主动。) The barrier both protects the organ and keeps it supplied with beneficial proteins. The team believe their results may suggest a new approach to treating Alzheimer’s disease(阿尔茨海默病).
在11月11日发表于《细胞》杂志的一项新研究中，由旧金山格拉德斯通神经疾病研究所神经科学家安德鲁·杨领导的研究团队表明，血脑屏障的复杂程度令人惊讶。通过记录小鼠体内被允许穿过屏障的蛋白质，研究人员发现，血脑屏障在维持大脑健康方面发挥的作用远比此前认为的更为主动。它既保护大脑，又为其持续供应有益蛋白质。该团队认为，他们的结果可能为治疗阿尔茨海默病提示一种新途径。
The blood-brain barrier is more like a bouncer(保安，门卫) than a brick wall. Its cells keep the harmful stuff out while letting in a select few essential molecules found in blood, such as oxygen and glucose, which fuel neural processes. It also ensures that conditions inside the brain are optimal by expelling(排出，驱逐) any unwanted molecular by-products(副产物) back into the bloodstream. By controlling what gets in and out, the barrier keeps the brain’s chemical environment stable and its neurons firing properly. But which molecules are on the brain’s guest list, and why, have so far remained unclear.(但哪些分子在受邀名单上、原因何在，迄今仍不清楚。)
血脑屏障更像一名保安，而不是一堵砖墙。它的细胞将有害物质挡在外面，同时允许血液中少数必需分子进入，例如为神经活动提供能量的氧气和葡萄糖。它还通过将不需要的分子副产物排回血液，确保大脑内部环境处于最佳状态。通过控制进出，血脑屏障维持大脑化学环境稳定，使神经元正常放电。但哪些分子在受邀名单上、原因何在，迄今仍不清楚。