Tong Xing, Li Wei, Xu Jia-Ying, Han Shufen, Qin Li-Qiang
Department of Nutrition and Food Hygiene, School of Public Health, Soochow University, Suzhou, China; Laboratory Center, Medical College of Soochow University, Suzhou, China.
Department of Nutrition and Food Hygiene, School of Public Health, Soochow University, Suzhou, China; Department of Nutrition, Shanghai 10th People's Hospital, Shanghai, China.
Nutrition. 2014 Sep;30(9):1076-80. doi: 10.1016/j.nut.2014.01.013. Epub 2014 Feb 15.
Whey protein (WP) has been reported to reduce body weight gain and improve glucose metabolism in obese individuals. This study aims to assess and compare the effects of WP and its hydrolysate-leucine (Leu) supplementation in non-obese, insulin-resistant (IR) rat models, particularly the effects on insulin sensitivity, lipid profile, and antioxidant activity.
Wistar rats were fed a diet consisting of 38.5% fat for 12 wk and 51.3% fat for an additional 4 wk to establish non-obese IR rats. The IR rats were then switched to regular AIN-93 diet containing 0% WP, 5% WP, 15% WP or 1.6% Leu for 8 wk. The Leu content was the same in the 15% WP and 1.6% Leu groups based on high-performance liquid chromatography. The IR rats' body weight, fasting blood glucose, fasting insulin, and homeostasis model assessment-insulin resistance were measured before and after supplementation. An oral glucose tolerance test was performed after supplementation. Body composition, plasma concentrations of the lipids profile, and antioxidant index also were analyzed.
No significant difference was observed in body weight, energy intake, and fasting blood glucose in the non-obese IR rats at the end of the experiment. Compared with the 0% WP group, the fasting insulin and homeostasis model assessment-insulin resistance significantly decreased in the 15% WP and 1.6% Leu groups. Furthermore, the blood glucose area under the curve of the oral glucose tolerance test was significantly less in the 15% WP and 1.6% Leu groups. There were no differences in the lipids profile, except for the increase in the high-density lipoprotein cholesterol in the 15% WP and 1.6% Leu groups. For the antioxidant index, the 15% WP group had significantly increased plasma levels for total antioxidation capacity, superoxide dismutase, and glutathione, and a decreased malondialdehyde concentration. The 1.6% Leu group was shown to have the same effect as the 15% WP group, except for the glutathione.
Our findings demonstrate that the supplementation of WP and Leu may improve IR and antioxidant stress without resulting in changes in body weight and energy intake in non-obese IR rats.
据报道，乳清蛋白（WP）可减少肥胖个体的体重增加并改善葡萄糖代谢。本研究旨在评估和比较WP及其水解产物 - 亮氨酸（Leu）补充剂对非肥胖、胰岛素抵抗（IR）大鼠模型的影响，特别是对胰岛素敏感性、血脂谱和抗氧化活性的影响。
将Wistar大鼠喂养含38.5%脂肪的饮食12周，然后再喂养含51.3%脂肪的饮食4周，以建立非肥胖IR大鼠模型。然后将IR大鼠转换为含0% WP、5% WP、15% WP或1.6% Leu的常规AIN - 93饮食，持续8周。基于高效液相色谱法，15% WP组和1.6% Leu组中的亮氨酸含量相同。在补充前后测量IR大鼠的体重、空腹血糖、空腹胰岛素和稳态模型评估 - 胰岛素抵抗。补充后进行口服葡萄糖耐量试验。还分析了身体组成、血脂谱的血浆浓度和抗氧化指数。
在实验结束时，非肥胖IR大鼠的体重、能量摄入和空腹血糖未观察到显著差异。与0% WP组相比，15% WP组和1.6% Leu组的空腹胰岛素和稳态模型评估 - 胰岛素抵抗显著降低。此外，15% WP组和1.6% Leu组口服葡萄糖耐量试验的血糖曲线下面积显著更小。除了15% WP组和1.6% Leu组中高密度脂蛋白胆固醇增加外，血脂谱没有差异。对于抗氧化指数，15% WP组的总抗氧化能力、超氧化物歧化酶和谷胱甘肽的血浆水平显著升高，丙二醛浓度降低。1.6% Leu组显示出与15% WP组相同的效果，但谷胱甘肽除外。
我们的研究结果表明，补充WP和Leu可能改善非肥胖IR大鼠的IR和抗氧化应激，而不会导致体重和能量摄入的变化。
