Background A previous clinical study reported that the addition of an amylopectin/chromium complex (ACr; Velositol®) to 6 g of whey protein (WP) significantly enhanced muscle protein synthesis (MPS). Branched-chain amino acids (BCAAs) are also well-known to enhance MPS. The aim of this study was to determine if the addition of ACr to BCAAs can enhance MPS and activate expression of the mammalian target of the rapamycin (mTOR) pathway compared to BCAAs and exercise alone in exercise-trained rats. Methods Twenty-four male Wistar rats were randomly divided into three groups ( n = 8 per group): (I) Exercise control, (II) Exercise plus BCAAs (0.465 g/kg BW, a 6 g human equivalent dose (HED)), and (III) Exercise plus BCAAs (0.465 g/kg BW) and ACr (0.155 g/kg BW, a 2 g HED). All animals were trained with treadmill exercise for 10 days. On the day of the single-dose experiment, rats were exercised at 26 m/min for 2 h and then fed, via oral gavage, study product. One hour after the consumption of study product, rats were injected with a bolus dose (250 mg/kg BW, 25 g/L) of phenylalanine labeled with deuterium to measure the fractional rate of protein synthesis (FSR). Ten minutes later, muscle tissue samples were taken to determine MPS measured by FSR and the phosphorylation of proteins involved in the mTOR pathway including mTOR, S6K1, and 4E-BP1. Results ACr combined with BCAAs increased MPS by 71% compared to the exercise control group, while BCAAs alone increased MPS by 57% over control ( p < 0.05). ACr plus BCAAs significantly enhanced phosphorylation of mTOR, S6K1 and 4E-BP1 compared to exercise control rats ( p < 0.05). The addition of ACr to BCAAs enhanced insulin levels, mTOR and S6K1 phosphorylation compared to BCAAs alone ( p < 0.05). Serum insulin concentration was positively correlated with the levels of mTOR, ( r = 0.923), S6K1 ( r = 0.814) and 4E-BP1 ( r = 0.953). Conclusions In conclusion, the results of this study provide evidence that the addition of ACr to BCAAs significantly enhances exercise-induced MPS, and the phosphorylation of mTOR signaling proteins, compared to BCAAs and exercise alone.

中文翻译：

---

在支链氨基酸中添加支链淀粉/铬复合物可增强大鼠骨骼肌中的肌肉蛋白质合成

背景 先前的一项临床研究报道，在 6 克乳清蛋白 (WP) 中添加支链淀粉/铬复合物 (ACr; Velositol®) 可显着增强肌肉蛋白合成 (MPS)。支链氨基酸 (BCAA) 也是众所周知的增强 MPS。本研究的目的是确定在运动训练的大鼠中，与 BCAAs 和单独运动相比，在 BCAAs 中添加 ACr 是否可以增强 MPS 并激活哺乳动物雷帕霉素 (mTOR) 通路靶标的表达。方法 24 只雄性 Wistar 大鼠随机分为三组（每组 n = 8）：（I）运动控制，（II）运动加 BCAA（0.465 g/kg BW，6 g 人体当量剂量（HED））和 (III) 运动加 BCAAs (0.465 g/kg BW) 和 ACr (0.155 g/kg BW, 2 g HED)。所有动物都接受了 10 天的跑步机运动训练。在单剂量实验当天，大鼠以 26 m/min 的速度运动 2 小时，然后通过口服管饲法喂食研究产品。消耗研究产品一小时后，给大鼠注射大剂量（250 mg/kg BW，25 g/L）的用氘标记的苯丙氨酸以测量蛋白质合成的分数速率（FSR）。十分钟后，采集肌肉组织样本以确定通过 FSR 测量的 MPS 和参与 mTOR 途径的蛋白质的磷酸化，包括 mTOR、S6K1 和 4E-BP1。结果 与运动对照组相比，ACr 联合 BCAAs 使 MPS 增加了 71%，而单独 BCAAs 比对照组增加了 57% (p < 0.05)。与运动对照组相比，ACr 加 BCAAs 显着增强了 mTOR、S6K1 和 4E-BP1 的磷酸化（p < 0.05）。与单独的 BCAA 相比，在 BCAA 中添加 ACr 可增强胰岛素水平、mTOR 和 S6K1 磷酸化 (p < 0.05)。血清胰岛素浓度与mTOR（r = 0.923）、S6K1（r = 0.814）和4E-BP1（r = 0.953）水平呈正相关。结论 总之，本研究结果提供的证据表明，与 BCAA 和单独运动相比，在 BCAA 中添加 ACr 可显着增强运动诱导的 MPS 和 mTOR 信号蛋白的磷酸化。