你有没有饭后犯困的经历?英国研究人员近期表示,这或许与食物的成分有关,含糖较多的食物容易让人犯困,而蛋白质含量较大的食物有助人们保持清醒。
英国剑桥大学等机构研究人员在新一期《神经元》杂志上报告说,他们监测了实验鼠在摄入不同食物时大脑中一种特殊细胞的变化。这种细胞能分泌一种名为“下丘脑泌素”的物质,这种物质能刺激肌体保持清醒和活跃。
研究人员发现,当实验鼠的食物中含有较多糖分时,由此产生的葡萄糖会妨碍这种细胞的功能,使其分泌下丘脑泌素的量减少,从而让实验鼠易困。如果食物中含有较多的蛋白质,由此产生的氨基酸则能起到相反的效果,有助实验鼠保持清醒。
研究人员丹尼斯·布尔达科夫说:“这项发现说明我们也许可以通过选择食物来帮助自己入睡或保持清醒,比如要保持清醒时,就不要在面包上涂抹果酱了,换而吃一些鸡蛋是不错的选择。”(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.