Mattison Julie A, Black Angela, Huck Jennifer, Moscrip Tammy, Handy April, Tilmont Edward, Roth George S, Lane Mark A, Ingram Donald K
Laboratory of Cardiovascular Science, Gerontology Research Center, National Institute on Aging, National Institutes of Health, 5600 Nathan Shock Drive, Baltimore, MD 21224, USA.
Neurobiol Aging. 2005 Jul;26(7):1117-27. doi: 10.1016/j.neurobiolaging.2004.09.013. Epub 2004 Dec 10.
Human studies have documented age-related declines in caloric intake that are pronounced at advanced ages. We examined caloric intake from a longitudinal study of aging in 60 male and 60 female rhesus monkeys (Macaca mulatta) collected for up to 10 years. Monkeys were provided a standardized, nutritionally fortified diet during two daily meals, and intake was measured quarterly. About half of the monkeys were on a regimen of caloric restriction (CR) representing about a 30% reduction in caloric intake compared to controls (CON) of comparable age and body weight. CR was applied to determine if this nutritional intervention retards the rate of aging in monkeys similar to observations in other mammalian studies. Following reproductive maturity at 6 years of age, there was a consistent age-related decline in caloric intake in these monkeys. Although males had higher intake than females, and CON had higher intake compared to CR, the sex and diet differences converged at older ages (>20 years); thus, older CR monkeys were no longer consuming 30% less than the CON. When adjusted for body weight, an age-related decline in caloric intake was still evident; however, females had higher intake compared to males while CR monkeys still consumed less food, and again differences converged at older ages. Motivation for food was assessed in 65 of the monkeys following at least 8 years in their respective diet groups. Using an apparatus attached to the home cage, following an overnight fast, monkeys were trained to reach out of their cage to retrieve a biscuit of their diet by pushing open a clear plastic door on the apparatus. The door was then locked, and thus the biscuit was irretrievable. The time spent trying to retrieve the biscuit was recorded as a measure of motivation for food. We observed an age-related decline in this measure, but found no consistent differences in retrieval time between CR and CON groups of comparable age and time on diet. The results demonstrate an age-related decline in food intake and motivation for food in rhesus monkeys paralleling findings in humans; however, we found no evidence that monkeys on a long-term CR regimen were more motivated for food compared to CON. Examining the relationship of selected blood proteins to food intake following 7-11 years on the study, we found a negative correlation between globulin and intake among males and females after accounting for differences in age. In addition, a positive correlation was observed between leptin and intake in males.
人体研究已记录到热量摄入随年龄增长而下降，在高龄时尤为明显。我们通过一项对60只雄性和60只雌性恒河猴（猕猴）进行的长达10年的衰老纵向研究，来检测热量摄入情况。在每日两餐时，给猴子提供标准化的、营养强化的饮食，并每季度测量摄入量。大约一半的猴子采用热量限制（CR）方案，与年龄和体重相当的对照组（CON）相比，热量摄入减少约30%。采用CR方案是为了确定这种营养干预措施是否能像在其他哺乳动物研究中观察到的那样，延缓猴子的衰老速度。在6岁达到生殖成熟后，这些猴子的热量摄入呈现出与年龄相关的持续下降。尽管雄性的摄入量高于雌性，且CON组的摄入量高于CR组，但在老年（>20岁）时，性别和饮食差异趋于一致；因此，老年CR组猴子的摄入量不再比CON组少30%。在根据体重进行调整后，热量摄入与年龄相关的下降仍然明显；然而，雌性的摄入量高于雄性，而CR组猴子仍然摄入较少的食物，并且差异在老年时再次趋于一致。在65只猴子分别处于各自饮食组至少8年后，评估了它们对食物的动机。使用连接在笼舍上的装置，在禁食一夜后，训练猴子伸出笼子，通过推开装置上的透明塑料门来获取它们饮食中的一块饼干。然后门被锁住，因此饼干无法取回。记录猴子试图取回饼干所花费的时间，作为对食物动机的一种衡量。我们观察到这一衡量指标随年龄增长而下降，但在年龄和饮食时间相当的CR组和CON组之间，未发现取回时间存在一致差异。结果表明，恒河猴的食物摄入量和对食物的动机随年龄增长而下降，这与人类的研究结果相似；然而，我们没有发现证据表明长期采用CR方案的猴子比CON组对食物更有动机。在研究进行7至11年后，检查选定血液蛋白与食物摄入量之间的关系，我们发现，在考虑年龄差异后，球蛋白与雄性和雌性的摄入量之间呈负相关。此外，在雄性中观察到瘦素与摄入量之间呈正相关。
