你有沒有飯后犯困的經(jīng)歷？英國研究人員近期表示,，這或許與食物的成分有關，含糖較多的食物容易讓人犯困，而蛋白質含量較大的食物有助人們保持清醒,。
英國劍橋大學等機構研究人員在新一期《神經(jīng)元》雜志上報告說，他們監(jiān)測了實驗鼠在攝入不同食物時大腦中一種特殊細胞的變化,。這種細胞能分泌一種名為“下丘腦泌素”的物質,，這種物質能刺激肌體保持清醒和活躍。
研究人員發(fā)現(xiàn),，當實驗鼠的食物中含有較多糖分時,，由此產(chǎn)生的葡萄糖會妨礙這種細胞的功能，使其分泌下丘腦泌素的量減少,，從而讓實驗鼠易困,。如果食物中含有較多的蛋白質，由此產(chǎn)生的氨基酸則能起到相反的效果,，有助實驗鼠保持清醒,。
研究人員丹尼斯·布爾達科夫說：“這項發(fā)現(xiàn)說明我們也許可以通過選擇食物來幫助自己入睡或保持清醒，比如要保持清醒時，就不要在面包上涂抹果醬了,，換而吃一些雞蛋是不錯的選擇,。”（生物谷 Bioon.com）
doi:10.1016/j.neuron.2011.08.027
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Activation of Central Orexin/Hypocretin Neurons by Dietary Amino Acids
Mahesh M. Karnani, John Apergis-Schoute, Antoine Adamantidis, Lise T. Jensen, Luis de Lecea, Lars Fugger, Denis Burdakov
Hypothalamic orexin/hypocretin (orx/hcrt) neurons regulate energy balance, wakefulness, and reward; their loss produces narcolepsy and weight gain. Glucose can lower the activity of orx/hcrt cells, but whether other dietary macronutrients have similar effects is unclear. We show that orx/hcrt cells are stimulated by nutritionally relevant mixtures of amino acids (AAs), both in brain slice patch-clamp experiments, and in c-Fos expression assays following central or peripheral administration of AAs to mice in vivo. Physiological mixtures of AAs electrically excited orx/hcrt cells through a dual mechanism involving inhibition of KATP channels and activation of system-A amino acid transporters. Nonessential AAs were more potent in activating orx/hcrt cells than essential AAs. Moreover, the presence of physiological concentrations of AAs suppressed the glucose responses of orx/hcrt cells. These results suggest a new mechanism of hypothalamic integration of macronutrient signals and imply that orx/hcrt cells sense macronutrient balance, rather than net energy value, in extracellular fluid.
