Allard Joanne S, Heilbronn Leonie K, Smith Carolina, Hunt Nicole D, Ingram Donald K, Ravussin Eric, de Cabo Rafael
Laboratory of Experimental Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America.
PLoS One. 2008 Sep 15;3(9):e3211. doi: 10.1371/journal.pone.0003211.
Calorie restriction (CR) produces several health benefits and increases lifespan in many species. Studies suggest that alternate-day fasting (ADF) and exercise can also provide these benefits. Whether CR results in lifespan extension in humans is not known and a direct investigation is not feasible. However, phenotypes observed in CR animals when compared to ad libitum fed (AL) animals, including increased stress resistance and changes in protein expression, can be simulated in cells cultured with media supplemented with blood serum from CR and AL animals. Two pilot studies were undertaken to examine the effects of ADF and CR on indicators of health and longevity in humans. In this study, we used sera collected from those studies to culture human hepatoma cells and assessed the effects on growth, stress resistance and gene expression. Cells cultured in serum collected at the end of the dieting period were compared to cells cultured in serum collected at baseline (before the dieting period). Cells cultured in serum from ADF participants, showed a 20% increase in Sirt1 protein which correlated with reduced triglyceride levels. ADF serum also induced a 9% decrease in proliferation and a 25% increase in heat resistance. Cells cultured in serum from CR participants induced an increase in Sirt1 protein levels by 17% and a 30% increase in PGC-1alpha mRNA levels. This first in vitro study utilizing human serum to examine effects on markers of health and longevity in cultured cells resulted in increased stress resistance and an up-regulation of genes proposed to be indicators of increased longevity. The use of this in vitro technique may be helpful for predicting the potential of CR, ADF and other dietary manipulations to affect markers of longevity in humans.
热量限制（CR）对许多物种都有诸多健康益处并能延长寿命。研究表明，隔日禁食（ADF）和运动也能带来这些益处。CR是否能延长人类寿命尚不清楚，且直接进行相关研究并不可行。然而，与自由进食（AL）的动物相比，CR动物所观察到的表型，包括应激抗性增加和蛋白质表达变化，在使用补充了CR和AL动物血清的培养基培养的细胞中能够被模拟出来。开展了两项初步研究来检验ADF和CR对人类健康和长寿指标的影响。在本研究中，我们使用从这些研究中收集的血清来培养人肝癌细胞，并评估其对细胞生长、应激抗性和基因表达的影响。将在节食期结束时收集的血清中培养的细胞与在基线期（节食期之前）收集的血清中培养的细胞进行比较。在ADF参与者的血清中培养的细胞，其Sirt1蛋白增加了20%，这与甘油三酯水平降低相关。ADF血清还使细胞增殖减少了9%，耐热性增加了25%。在CR参与者的血清中培养的细胞，其Sirt1蛋白水平增加了17%，PGC-1α mRNA水平增加了30%。这项首次利用人血清在体外研究对培养细胞中健康和长寿标志物影响的研究，导致了应激抗性增加以及被认为是长寿增加指标的基因上调。这种体外技术的应用可能有助于预测CR、ADF和其他饮食干预对人类长寿标志物的潜在影响。
