生物周期节律与衰老

海量资料下载 免费学习英语 www.englishvip.com/xinlw.htm （申请网址） Human sleeping and waking patterns are largely governed by an internal circadian clock that corresponds closely with the 24-hour cycle of light and darkness. This circadian clock also controls other body functions, such as metabolism and temperature regulation. Studies in animals have found that when that rhythm gets thrown off（摆脱，关闭）, health problems including obesity and metabolic disorders such as diabetes can arise. Studies of people who work night shifts have also revealed an increased susceptibility to diabetes.   A new study from MIT shows that a gene called SIRT1, previously shown to protect against diseases of aging, plays a key role in controlling these circadian rhythms. The researchers found that circadian function decays with aging in normal mice, and that boosting their SIRT1 levels in the brain could prevent this decay. Conversely, loss of SIRT1 function impairs circadian control in young mice, mimicking what happens in normal aging.   Since the SIRT1 protein itself was found to decline with aging in the normal mice, the findings suggest that drugs that enhance SIRT1 activity in humans could have widespread health benefits, says Leonard Guarente, the Novartis Professor of Biology at MIT and senior author of a paper describing the findings in the June 20 issue of Cell.   "If we could keep SIRT1 as active as possible as we get older, then we'd be able to retard aging in the central clock in the brain, and health benefits would radiate from that," Guarente says.   Staying on schedule   In humans and animals, circadian patterns follow a roughly 24-hour cycle, directed by the circadian control center of the brain, called the suprachiasmatic nucleus (SCN), located in the hypothalamus.   "Just about everything that takes place physiologically is really staged along the circadian cycle," Guarente says. "What's now emerging is the idea that maintaining the circadian cycle is quite important in health maintenance, and if it gets broken, there's a penalty to be paid in health and perhaps in aging."   Last year, Guarente found that a robust circadian period correlated with longer lifespan in mice. That got him wondering what role SIRT1, which has been shown to prolong lifespan in many animals, might play in that phenomenon. SIRT1, which Guarente first linked with aging more than 15 years ago, is a master regulator of cell responses to stress, coordinating a variety of hormone networks, proteins and genes to help keep cells alive and healthy. 密切对应光明与黑暗的24小时周期的内部生物钟主要受人类睡眠和醒来模式。这种生物钟也控制身体其他功能，如新陈代谢和体温调节。对动物的研究已经发现，当被揭去，节奏（摆脱，关闭），肥胖和代谢性疾病如糖尿病的健康问题，包括可能出现。上夜班的人谁的研究也显示糖尿病的易感性增加。   来自麻省理工学院的一项新研究显示，一种基因名为SIRT1，先前的研究显示，以防止疾病的老化，在控制这些昼夜节律起着关键的作用。研究人员发现，与正常小鼠的老化，提高他们的SIRT1水平在大脑的生物钟功能衰减可以防止这种衰变。相反，SIRT1的功能丧失损害年轻小鼠的昼夜节律的控制，模仿正常老化会发生什么。   伦纳德·瓜伦特，诺华在麻省理工学院的生物学教授和资深作者的论文说，由于SIRT1的蛋白本身被发现在正常小鼠老化下降，研究结果明，提高SIRT1的活性在人类的药物可能产生广泛的健康益处描述的结果，在6月20日的Cell杂志上。   ，“瓜伦特说：”如果我们能保持尽可能活跃SIRT1当我们变老，那么我们就能够在大脑中的中央时钟延缓衰老，健康的好处会从该辐射。   按行事   在人类和动物中，按照大约24小时的周期，直接由大脑的生物钟控制中心，称位于下丘脑视交叉上核（SCN），昼夜模式。   “只是生理上发生的一切，真的是沿昼夜周期上演，”瓜伦特说。“什么是现在新兴的想法，保持昼夜周期是非常重要的健康维护，如果它被打破，有一个也许在健康和老化支付的罚款。”   去年，瓜伦特发现，一个强有力的昼夜周期与小鼠寿命更长。让他知道SIRT1什么样的角色，这已被证明在许多动物的寿命延长，可能发挥这种现象。SIRT1，瓜伦特与衰老超过15年前，第一个链接是一个主控调节细胞反应的压力，协调各种激素的网络，蛋白质和基因，以帮助保持细胞健康地活着。 “成千上万人疯狂下载。。。。。。 更多价值连城的绝密英语学习资料， 洛基内部秘密英语，技巧，策略 请在 网上 申请报名” 洛基国际英语 竭诚为您服务