Ling Pei-Ra, Bistrian Bruce R
Department of Medicine, Nutrition/Infection Laboratory, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
Metabolism. 2009 Jun;58(6):835-42. doi: 10.1016/j.metabol.2009.03.002.
We previously demonstrated that feeding a 2% protein AIN-76 diet ad libitum for 14 days resulted in substantial clinical and biochemical changes including weight loss, hypoglycemia, hypoalbuminemia, higher levels of plasma cytokines, oxidative stress in the liver, and activation of inflammatory signaling to interleukin (IL)-6, as compared with a 20% protein diet. In the present study, 54 rats were randomly given a standard rat chow diet ad libitum, or a 25% or 50% reduction of this intake for 14 days. The results showed that weight gain was less in the 25% food-restricted group and halted in the 50% group as compared with the control group. Unlike protein restriction, neither level of food restriction altered plasma levels of albumin and glucose, the hepatic protein abundance of signal transducers and activators of transcriptions and of mitogen-activated protein kinases, or the hepatic contents of total glutathione and malondialdehyde. The intracellular signaling in response to IL-6 stimulation was also well maintained. However, both levels of food restriction elevated IL-1 and corticosterone in plasma, did not alter ghrelin, and decreased plasma levels of free fatty acids. Because these latter 3 markers were not examined previously, 20 rats were fed an AIN-76 diet, either with 20% or 2% protein, ad libitum for 14 days. The 2% protein diet significantly decreased plasma levels of free fatty acids and increased ghrelin and corticosterone as compared with the 20% protein diet. Thus, food restriction, where all essential nutrients are reduced in proportion, is a physiologic stress that, while limiting growth, does not activate or impair the systemic inflammatory response, whereas a very low protein diet with little change in energy intake has a substantial impact on systemic inflammation, body composition, and growth.
我们之前证明，与20%蛋白质饮食相比，随意喂食2%蛋白质的AIN - 76饮食14天会导致显著的临床和生化变化，包括体重减轻、低血糖、低白蛋白血症、血浆细胞因子水平升高、肝脏氧化应激以及炎症信号向白细胞介素（IL）- 6的激活。在本研究中，54只大鼠被随机随意给予标准大鼠饲料，或减少25%或50%的摄入量，持续14天。结果显示，与对照组相比，25%食物限制组的体重增加较少，而50%食物限制组的体重增加停止。与蛋白质限制不同，两种食物限制水平均未改变血浆白蛋白和葡萄糖水平、肝脏中信号转导和转录激活因子以及丝裂原活化蛋白激酶的蛋白质丰度，也未改变肝脏中总谷胱甘肽和丙二醛的含量。对IL - 6刺激的细胞内信号传导也保持良好。然而，两种食物限制水平均提高了血浆中IL - 1和皮质酮水平，未改变胃饥饿素，并降低了血浆游离脂肪酸水平。由于之前未检测后这3种标志物，20只大鼠被随意喂食含20%或2%蛋白质的AIN - 76饮食，持续14天。与20%蛋白质饮食相比，2%蛋白质饮食显著降低了血浆游离脂肪酸水平，并增加了胃饥饿素和皮质酮水平。因此，食物限制（所有必需营养素按比例减少）是一种生理应激，虽然会限制生长，但不会激活或损害全身炎症反应，而能量摄入变化不大的极低蛋白质饮食对全身炎症、身体组成和生长有重大影响。
