Activation of the mechanistic target of rapamycin (mTOR)-controlled anabolic signaling pathways in skeletal muscle of rodents and humans are responsive to level of dietary protein supply, with maximal activation and rates of protein synthesis achieved with 0.2-0.4 g protein/kg body weight (BW). In horses, few data are available on required level of dietary protein to maximize protein synthesis for maintenance and growth of skeletal muscle. To evaluate the effect of dietary protein level on muscle mTOR pathway activation, five mares received different amounts of a protein supplement that provided 0, 0.06, 0.125, 0.25 or 0.5 g of CP/kg BW per meal in a 5 x 5 Latin square design. On each sample day, horses were fasted overnight and were fed only their protein meal the following morning. A pre- (0 min) and postprandial (90 min) blood sample was collected and a gluteus medius muscle sample was obtained 90 min after feeding the protein meal. Blood samples were analyzed for glucose, insulin and amino acid concentrations. Activation of mTOR pathway components (mTOR and S6-ribosomal protein, rpS6) in the muscle samples was measured by western immunoblot analysis.

中文翻译：

---

调节马骨骼肌蛋白质合成的途径以剂量依赖性方式对蛋白质摄入的分级水平做出反应。

啮齿动物和人类骨骼肌中雷帕霉素 (mTOR) 控制的合成代谢信号通路的机械靶标的激活对膳食蛋白质供应水平有反应，最大激活和蛋白质合成速率达到 0.2-0.4 g 蛋白质/kg 体重（体重）。在马中，很少有关于膳食蛋白质所需水平的数据，以最大限度地提高蛋白质合成以维持和生长骨骼肌。为了评估膳食蛋白质水平对肌肉 mTOR 通路激活的影响，五匹母马接受了不同量的蛋白质补充剂，在 5 x 5 拉丁方设计中，每餐提供 0、0.06、0.125、0.25 或 0.5 克 CP/kg BW . 在每个采样日，马都禁食过夜，第二天早上只喂它们的蛋白质餐。收集餐前（0 分钟）和餐后（90 分钟）的血液样本，并在喂食蛋白质餐后 90 分钟获取臀中肌样本。分析血样的葡萄糖、胰岛素和氨基酸浓度。通过蛋白质免疫印迹分析测量肌肉样品中 mTOR 通路组分（mTOR 和 S6-核糖体蛋白，rpS6）的激活。