青岛诺德和华韩哪家好:头脑中年轻的源泉

Dracula(那个著名的吸血鬼)也许真的说对了一件事情：年轻的血液可以修复一个年老的身躯。科学家们已经发现一只三个月大的老鼠的血液可以慢慢的使一只年老的老鼠的大脑重造新的脑细胞。他们还没有确定重新变年轻的因素，但是他们发现了一种血液中的化合物似乎会促进大脑衰老。

As the body ages, the brain gradually becomes more sluggish. Even in people lucky enough to dodge neurodegenerative disorders such as Alzheimer's disease, fewer new neurons are created from stem cells in the brain, and the activity of existing neurons weakens. Neuroscientist Tony Wyss-Coray of Stanford University School of Medicine in Palo Alto, California, suspected that the changes could be mediated by factors in the blood.

随着身体变老，大脑会逐渐变迟钝。即使在那些幸免于神经退化性疾病(例如老年痴呆症)的人之中，也很少有新的神经元从大脑的原细胞中再被创造出来，而且已经存在的神经元也会逐渐的变弱。来自加州圣保罗斯坦福医药学院的神经科学家Tony Wyss Coray猜想这些衰老变化也许可以被血液中的某些因素调停缓和。

Previous research has shown that giving young blood to older mice boosts their immune system and muscle function. Wyss-Coray wondered whether the same might be true in the brain. Although the so-called blood-brain barrier blocks many large molecules from entering the brain from the bloodstream, the barrier isn't sealed tight everywhere, which might allow some compounds to get through. It's leakiest at places where there are brain stem cells, suggesting that these neuron precursors may have interaction with the circulatory system.

以前的一些研究显示给老老鼠注射年轻老鼠血液会激发老老鼠的免疫系统和肌肉功能。Wyss Coray就想这个现象会不会也出现在大脑中。虽然血液大脑界限阻隔了很多血液中的大分子进入大脑，但这层界限不是在所有地方都密封得很好的，这就有机会让某些混合物通过。这些界限在大脑原细胞处尤其密封性的不好，暗示着这些神经元前体也许有机会和循环系统接触。

Wyss-Coray's team measured neurogenesis, the creation of new neurons from stem cells, in mice that were 3 months old and mice that were almost 2 years old and considered adults. Then they surgically connected the circulatory systems of pairs of young and old mice. The number of new cells in one region of the brain's hippocampus, related to memory formation, went from fewer than 400 to almost 1000 in the older mice. In the younger mice, it dropped by almost a quarter, the scientists report today in Nature. "It worked in both directions," says Wyss-Coray. "The age of the blood has a special effect on the brain."

Wyss Coray的团队测量了三个月大的老鼠和大概有两岁大的老鼠的神经形成---就是新的神经元细胞从原细胞中产生的过程。然后他们用手术办法把年轻老鼠和老老鼠的循环系统连接起来。研究者在自然杂志中说：老老鼠大脑中的海马体---一种和记忆形成有关的组织---里面的新细胞从少于400个暴涨到将近1000个，而年轻老鼠的新细胞几乎下降了1/4。“这是双向运作的”，Wyss Coray说，“血液的年龄对大脑有特殊影响”。

When the researchers gave young mice daily injections of older blood, not only did neurogenesis decrease, but their learning and memory scores in a water maze test got worse. They made more than twice the number of mistakes in the maze after a day of training and a day of testing.

当研究者们每天把老的血液注入年轻老鼠中，年轻老鼠下降的不只有神经形成，他们在水迷宫测试中表现出的的学习和记忆能力也会变差。经过一天训练和一天测试，他们比原来(没被注射的正常年轻老鼠)多犯了一倍的错误。

To isolate the compound responsible for these changes, Wyss-Coray and his colleagues focused on 66 blood-borne chemicals. They identified 17 that increased in concentration as a mouse aged. One of them, a protein called CCL11, was enough to slow neurogenesis when injected into the bloodstream on its own. The researchers haven't yet found a compound that does the reverse—turning up neurogenesis. But finding more neurogenesis in old mice given young blood suggests that it exists.

为了隔离出导致这些改变的混合物，Wyss Coray和他的同事把目标锁定在血液中的66种化学品。他们确认了17种随着年龄增长而增长的化合物。其中一种叫CCL11的蛋白质，足以在单独被注射入血液的情况下导致神经形成减缓。研究者们还没有找到一种能起到相反效果---加快神经形成的化合物。但是被注射了年轻血液后老老鼠体内形成了更多神经元这一现象暗示了这种化合物的存在。

The findings offer a proof of principle that neurogenesis can be controlled through the blood, a paradigm-shifting idea for treating neurodegenerative disease, Wyss-Coray says. "The big implication here is that we can potentially affect brain aging and degradation, even dementia, by targeting factors in the periphery rather than having to target the brain directly."

这些发现证明了神经形成这一过程可以通过血液控制的原理，这一原理会是对治疗神经退化性疾病一个思考模式的转移。Wyss Coray 说“大画面是我们可以通过控制边缘因素而不是大脑本身来影响大脑的老化和退化，甚至痴呆程度”。

Richard Ransohoff, a neuroscientist at the Cleveland Clinic in Ohio, says the new study is a leap toward understanding how neurogenesis is controlled in the adult brain. "I think it's very exciting to know that the aging stem cell population can remain responsive to environmental cues." But more work is needed to fully understand how all the cues work, he says, and whether the findings hold true in people.

Richard Ransohoff，俄亥俄克利夫兰诊所的神经学家，说这个新的发现是对于成熟大脑中神经形成方式了解的一大步飞跃。“我认为能知道老化的原细胞还会对外界诱因有所反应这一点是很令人兴奋的”。但是还需要进一步地研究具体这些诱因有何作用，他说，还有这些结果在人体内是否适用。

"One of the next steps is to take these factors and measure them in aging humans," Ransohoff says. "You might take patients with neurodegenerative diseases and see how the factors are different, or follow how they change over time in people with early cases of disease."

“接下来的一步就是在人体内发现并测量这些因素”，Ransohoff说，“你可以试验一下有神经退化疾病的病人，然后看这些因素有什么不同，也可以追踪这些因素从轻度神经退化到严重的过程中是如何变化的”。

Wyss-Coray plans to start out by analyzing more blood-borne factors in mice. His team is planning a screen of hundreds more factors to see what else may be controlling the aging of the brain.

Wyss Coray计划先分析老鼠体内更多的血液因素，他的团队计划着扫描几百个其他因素来看还有没有其他因素也对大脑老化起着决定性作用。