睡眠过程中的大脑能量补充
睡眠过程中的大脑能量补充
2010/07/11 06:33:31
根据6月30日的Journal of Neuroscience杂志上的一项最新研究，在睡眠的初始阶段，大脑一些区域中的能量水平显著降低，而这些区域在清醒状态下是表现活跃的。研究表明大脑在睡眠的时候经历着细胞能量的补充过程，该过程对清醒状态下大脑执行正常的功能来说是必需的。
晚间良好的休息能够使我们恢复精力，但是在睡眠过程中实际发生的生物学过程却很难捉摸。科学家认为大脑的能量水平是夜间恢复的关键。文章作者Basheer教授表示，他们的这项研究将解释一个重要的生物学问题，即睡眠的功能。在某种程度上他们也有点惊讶，因为最近这些年还没有科研人员使用最敏感的测量方法进行大脑能量研究。
在这项研究中，研究人员测量了大鼠中三磷酸腺苷（ATP）的水平，结果发现当老鼠处在非快速动眼睡眠中，在4个清醒状态下活跃的大脑关键区域中，ATP水平增加，同时伴随着大脑活性的全面降低。当大鼠处在清醒状态时，ATP水平是稳定的。此外，当轻轻触碰正常睡眠时间过去3或6个小时的清醒老鼠，ATP水平也不会增加。因此，研究人员得出结论睡眠对于ATP能量补充是必需的，保持大鼠处在清醒状态则会阻止ATP水平上升。
美国睡眠研究方面的专家Robert Greene博士认为，这项研究为”依赖于睡眠的能量上升对于促进能量补充的生物合成过程来说是必需的”这一理论提供了一个十分有趣的证据。另外Robert Greene博士就该发现提出了一个疑问，这项研究的作者提出睡眠过程中能量的上升和大脑中细胞活性的降低有关，但是这同样也可能是一些其他的因素导致的，其中就包括大脑的细胞信号过程。
The Journal of Neuroscience doi:10.1523/JNEUROSCI.1423-10.2010
Sleep and Brain Energy Levels: ATP Changes during Sleep
Markus Dworak, Robert W. McCarley, Tae Kim, Anna V. Kalinchuk, and Radhika Basheer
Sleep is one of the most pervasive biological phenomena, but one whose function remains elusive. Although many theories of function, indirect evidence, and even common sense suggest sleep is needed for an increase in brain energy, brain energy levels have not been directly measured with modern technology. We here report that ATP levels, the energy currency of brain cells, show a surge in the initial hours of spontaneous sleep in wake-active but not in sleep-active brain regions of rat. The surge is dependent on sleep but not time of day, since preventing sleep by gentle handling of rats for 3 or 6 h also prevents the surge in ATP. A significant positive correlation was observed between the surge in ATP and EEG non-rapid eye movement delta activity (0.5–4.5 Hz) during spontaneous sleep. Inducing sleep and delta activity by adenosine infusion into basal forebrain during the normally active dark period also increases ATP. Together, these observations suggest that the surge in ATP occurs when the neuronal activity is reduced, as occurs during sleep. The levels of phosphorylated AMP-activated protein kinase (P-AMPK), well known for its role in cellular energy sensing and regulation, and ATP show reciprocal changes. P-AMPK levels are lower during the sleep-induced ATP surge than during wake or sleep deprivation. Together, these results suggest that sleep-induced surge in ATP and the decrease in P-AMPK levels set the stage for increased anabolic processes during sleep and provide insight into the molecular events leading to the restorative biosynthetic processes occurring during sleep.