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摘要 : 2017年8月1日,国际顶级学术期刊《PLOS One》发表了美国加州大学旧金山分校Kaveh Ashrafi研究员的一篇研究论文,研究发现限制卡路里摄入可能还会促进大脑发展。

2017年8月1日,国际顶级学术期刊《PLOS ONE》发表了美国加州大学旧金山分校Kaveh Ashrafi研究员的一篇研究论文,研究发现限制卡路里摄入可能还会促进大脑发展。

人们已对限制卡路里摄入的好处略知一二,比如可让苍蝇、小鼠和猴子的寿命更长。Ashrafi团队训练秀丽隐杆线虫将化学物质——丁酮的气味同食物奖励联系起来。从圆形中间移动到掺有丁酮的一边的蠕虫比例,可证明它们在多大程度上消化了上述“课程”。圆形的相反一边则闻起来像是酒精。

接受测试的蠕虫可以自由进食,或者禁食1小时,也可以选用卡路里摄入受限的饮食。少摄入一半正常卡路里的蠕虫发生移动的比例,是被允许自由进食的蠕虫的两倍。禁食的蠕虫也发生了同样的情况。这表明,低卡路里饮食和短期禁食能产生类似效果。

摄入较少卡路里可能通过消耗一种被称为犬尿喹啉酸的大脑化学物质发挥作用。这反过来激活了同学习过程相关的神经元。当研究人员减少了犬尿喹啉酸,蠕虫的学习能力在卡路里摄入未受限的情况下也得到了改善。

Ashrafi介绍说,类似的现象同样出现在哺乳动物中。一项2008年的研究发现,卡路里摄入减少30%的60岁左右的人,更擅长学习单词列表。

澳大利亚悉尼大学的Devin Wahl表示,从进化论的角度来看,这是合理的。“当你在寻找食物时,大脑运行需要维持在高水平状态,因为你正试图击败竞争者。”Wahl说,“一旦你吃过一顿大餐后,就只想要睡觉了。”不过,研究发现,强烈的饥饿感会损伤认知功能。这可能是因为过度饥饿让人们全神贯注于对食物的念想上。

原文链接:

The beneficial effects of dietary restriction on learning are distinct from its effects on longevity and mediated by depletion of a neuroinhibitory metabolite

原文摘要:

In species ranging from humans to Caenorhabditis elegans, dietary restriction (DR) grants numerous benefits, including enhanced learning. The precise mechanisms by which DR engenders benefits on processes related to learning remain poorly understood. As a result, it is unclear whether the learning benefits of DR are due to myriad improvements in mechanisms that collectively confer improved cellular health and extension of organismal lifespan or due to specific neural mechanisms. Using an associative learning paradigm in C. elegans, we investigated the effects of DR as well as manipulations of insulin, mechanistic target of rapamycin (mTOR), AMP-activated protein kinase (AMPK), and autophagy pathways—processes implicated in longevity—on learning. Despite their effects on a vast number of molecular effectors, we found that the beneficial effects on learning elicited by each of these manipulations are fully dependent on depletion of kynurenic acid (KYNA), a neuroinhibitory metabolite. KYNA depletion then leads, in an N-methyl D-aspartate receptor (NMDAR)-dependent manner, to activation of a specific pair of interneurons with a critical role in learning. Thus, fluctuations in KYNA levels emerge as a previously unidentified molecular mechanism linking longevity and metabolic pathways to neural mechanisms of learning. Importantly, KYNA levels did not alter lifespan in any of the conditions tested. As such, the beneficial effects of DR on learning can be attributed to changes in a nutritionally sensitive metabolite with neuromodulatory activity rather than indirect or secondary consequences of improved health and extended longevity.

doi:10.1371/journal.pbio.2002032

作者:Kaveh Ashrafi 点击:

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