Department of Food and Nutrition, Obesity/Diabetes Research Center, Hoseo University, Asan 31499, Republic of Korea; Department of Bio-Convergence System, Hoseo University, Asan 31499, Republic of Korea.
Department of Bio-Convergence System, Hoseo University, Asan 31499, Republic of Korea.
Biomed Pharmacother. 2021 May;137:111415. doi: 10.1016/j.biopha.2021.111415. Epub 2021 Feb 23.
Aging alters body composition to induce sarcopenia, particularly in women, but the mechanism remains unclear. We hypothesized that silk peptide(SP) intake could prevent an age-related decrease in muscle mass and strength in middle-aged female rats and explored the action mechanism. After the acute intake of SP and defatted soybean peptides, serum concentrations of amino acids were measured in ten middle-aged rats in each group. Forty 12-month-old female Sprague-Dawley rats were fed a high-fat and high-carbohydrate diet for 12 weeks including 0.5 g casein/kg body weight(BW)/day(Aged), 0.15 g SP plus 0.35 g casein/kg BW/day(Low-SP), 0.5 g SP/kg BW/day(High-SP), or 40 mg metformin plus 0.5 g casein/kg BW/day(Metformin). Ten rats aged 7-week old(Young) had the same treatment as the Aged-group. The body composition, grip strength, glucose metabolism, intestinal tissue morphology, and gut microbiota were also determined. After an acute consumption, total amino acids were more quickly absorbed and maintained at higher levels in SP than soybean peptides. Lean body mass(LBM) and grip strength were lower in the Aged-group than the Young and Low-SP groups, and the High-SP regimen increased these parameters as much as the Young-group. Serum concentrations and mRNA expression of TNF-α in the gastrocnemius and quadriceps muscles were higher in the Aged-group than the Young-group, whereas SP intake reduced their serum levels and skeletal muscles. Glucose and insulin tolerance indicated that insulin resistance was elevated in the Aged-group compared to the Young-group, while Low-SP and High-SP alleviated them as much as the Young-group. High-SP increased serum propionate and butyrate concentrations compared to the Aged-group. SP intake increased the relative abundance of Bacteroides and Prevotella and decreased Blautia and Clostridium in the feces. In conclusion, SP intake protects against a decrease in lean body mass and grip strength in middle-aged female rats. The protection was partly related to maintaining higher serum concentrations of total amino acids after SP consumption and decreasing inflammation and insulin resistance through gut microbiota modulation.
衰老是引起肌肉减少症的原因，特别是在女性中，但具体机制尚不清楚。我们假设丝肽（SP）的摄入可以防止中年雌性大鼠的肌肉质量和力量随着年龄的增长而下降，并探索其作用机制。在 SP 和脱脂大豆肽的急性摄入后，每组 10 只中年大鼠的血清氨基酸浓度进行了测量。40 只 12 月龄的雌性 Sprague-Dawley 大鼠喂食高脂肪和高碳水化合物饮食 12 周，包括 0.5g 酪蛋白/kg 体重/天（老龄组）、0.15g SP 和 0.35g 酪蛋白/kg BW/天（低 SP 组）、0.5g SP/kg BW/天（高 SP 组）或 40mg 二甲双胍加 0.5g 酪蛋白/kg BW/天（二甲双胍组）。10 只 7 周龄的大鼠（年轻组）与老龄组进行相同的处理。还测定了身体成分、握力、葡萄糖代谢、肠道组织形态和肠道微生物群。急性消耗后，总氨基酸在 SP 中的吸收速度更快，维持水平更高。与年轻组和低 SP 组相比，老龄组的瘦体重（LBM）和握力较低，高 SP 方案使这些参数增加到与年轻组相同的水平。与年轻组相比，老龄组腓肠肌和股四头肌的血清 TNF-α浓度和 mRNA 表达更高，而 SP 摄入降低了其血清水平和骨骼肌水平。葡萄糖和胰岛素耐量表明，与年轻组相比，老龄组的胰岛素抵抗升高，而低 SP 和高 SP 组则与年轻组一样缓解了胰岛素抵抗。与老龄组相比，高 SP 组血清丙酸盐和丁酸盐浓度增加。SP 摄入增加了粪便中拟杆菌属和普雷沃氏菌属的相对丰度，降低了 Blautia 和 Clostridium 的丰度。总之，SP 摄入可防止中年雌性大鼠瘦体重和握力下降。这种保护部分与 SP 摄入后总氨基酸血清浓度升高以及通过肠道微生物群调节降低炎症和胰岛素抵抗有关。
