Food for Health Ireland, University of Limerick, Limerick, Ireland.
Human Sciences Research Unit, University of Limerick, Limerick, Ireland.
PLoS One. 2019 Nov 19;14(11):e0220757. doi: 10.1371/journal.pone.0220757. eCollection 2019.
The purpose of this study was to compare the effect of treating skeletal muscle cells with media conditioned by postprandial ex vivo human serum fed with either isonitrogenous Non-Essential Amino Acid (NEAA) or a whey protein hydrolysate (WPH) on stimulating Muscle Protein Synthesis (MPS) in C2C12 skeletal muscle cells.
Blood was taken from six young healthy males following overnight fast (fasted) and 60 min postprandial (fed) ingestion of either WPH or NEAA (0.33 g.kg-1 Body Mass). C2C12 myotubes were treated with media conditioned by ex vivo human serum (20%) for 4 h. Activation of MPS signalling (phosphorylation of mTOR, P70S6K and 4E-BP1) were determined in vitro by Western Blot and subsequent MPS were determined in vitro by Western Blot and surface sensing of translation technique (SUnSET) techniques, respectively.
Media conditioned by NEAA fed serum had no effect on protein signalling or MPS compared to fasted, whereas media conditioned by WPH fed serum significantly increased mTOR (Ser2448), P70S6K and 4E-BP1 phosphorylation (p<0.01, p<0.05) compared to fasted serum. Furthermore, the effect of media conditioned by WPH fed serum on protein signalling and MPS was significantly increased (p<0.01, p<0.05) compared to NEAA fed serum.
In summary, media conditioned by NEAA fed serum did not result in activation of MPS. Therefore, these in vitro findings suggest the use of isonitrogenous NEAA acts as an effective control for comparing bioactivity of different proteins on activation of MPS.
本研究旨在比较经餐后离体人血清培养并分别添加等氮非必需氨基酸（NEAA）或乳清蛋白水解物（WPH）后，处理骨骼肌细胞对刺激 C2C12 骨骼肌细胞肌肉蛋白合成（MPS）的影响。
6 名年轻健康男性空腹过夜（禁食）后，分别口服 WPH 或 NEAA（0.33g/kg 体重）60min 后取血。C2C12 肌管用离体人血清（20%）培养 4 小时。通过 Western Blot 检测体外 MPS 信号转导（mTOR、P70S6K 和 4E-BP1 的磷酸化），并通过 Western Blot 和表面翻译感应技术（SUnSET）分别检测体外 MPS。
与禁食相比，NEAA 喂养血清培养的条件培养基对蛋白质信号或 MPS 没有影响，而 WPH 喂养血清培养的条件培养基显著增加了 mTOR（Ser2448）、P70S6K 和 4E-BP1 的磷酸化（p<0.01，p<0.05），与禁食血清相比。此外，与 NEAA 喂养血清相比，WPH 喂养血清培养的条件培养基对蛋白质信号和 MPS 的影响显著增加（p<0.01，p<0.05）。
综上所述，NEAA 喂养血清并未导致 MPS 的激活。因此，这些体外研究结果表明，使用等氮 NEAA 作为比较不同蛋白质对 MPS 激活的生物活性的有效对照。
