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Blue whiting (BW) represents an underutilised fish species containing a high-quality protein and amino acid (AA) profile with numerous potentially bioactive peptide sequences, making BW an economic and sustainable alternative source of protein. This study investigated the impact of three different BW protein hydrolysates (BWPH-X, Y and Z) on growth, proliferation and muscle protein synthesis (MPS) in skeletal muscle (C2C12) myotubes. BWPHs were hydrolysed using different enzymatic and heat exposures and underwent simulated gastrointestinal digestion (SGID), each resulting in a high degree of hydrolysis (33.41–37.29%) and high quantities of low molecular mass peptides (86.17–97.12% <1 kDa). C2C12 myotubes were treated with 1 mg protein equivalent/mL of SGID-BWPHs for 4 h. Muscle growth and myotube thickness were analysed using an xCelligence™ platform. Anabolic signalling (phosphorylation of mTOR, rpS6 and 4E-BP1) and MPS measured by puromycin incorporation were assessed using immunoblotting. BWPH-X significantly increased muscle growth (p < 0.01) and myotube thickness (p < 0.0001) compared to the negative control (amino acid and serum free media). Muscle protein synthesis (MPS), as measured by puromycin incorporation, was significantly higher after incubation with BWPH-X compared with the negative control, but did not significantly change in response to BWPH-Y and Z treatments. Taken together, these preliminary findings demonstrate the anabolic potential of some but not all BWPHs on muscle enhancement, thus providing justification for human dietary intervention studies to confirm and translate the results of such investigations to dietary recommendations and practices. [ABSTRACT FROM AUTHOR]

Purpose: 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. Methods: 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. Results: 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. Conclusion: 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. [ABSTRACT FROM AUTHOR]

New Findings: What is the central question of this study? Can medium conditioned by ex vivo human serum regulate muscle protein synthesis in skeletal muscle cells in vitro? What is the main finding and its importance? This study demonstrates that medium conditioned by ex vivo human serum can regulate muscle protein synthesis in skeletal muscle cells in vitro via the mammalian Target of Rapomycin (mTOR) pathway, and this can be regulated differentially by fed and fasted ex vivo human serum. Abstract: Human serum embodies the integrated systemic response to any condition or perturbation, which may regulate muscle protein synthesis (MPS). Conditioning of medium with human serum represents a physiologically relevant method of regulating MPS in vitro. The primary purpose of the study was the development of a model using ex vivo human serum to condition medium and regulate MPS in in vitro skeletal muscle cells. Four young healthy men reported to the laboratory after an overnight fast and were fed with 0.33 g (kg body mass)−1 whey protein. Blood samples were taken before (Fasted) and 60 min postprandial (Fed). Fully differentiated C2C12 skeletal muscle cells were nutrient and serum deprived for 1 h and subsequently treated with medium conditioned with Fasted or Fed ex vivo human serum (20%) for 4 h. The MPS was measured using the surface sensing of translation technique and activation of mTOR, P70S6K and 4EBP1 by Western blot. Fasted and fed ex vivo human serum increased MPS (P < 0.05). Although a strong effect (ƞ2 = 0.36) for increased MPS in Fed relative to Fasted was observed, this was not statistically significant (P > 0.05). Activation of mTOR, P70S6K and 4EBP1 was significantly increased after treatment with Fed compared with Fasted ex vivo human serum (P < 0.05). Here, we developed and optimized the conditions for culture of C2C12 skeletal muscle cells, measurement of MPS and signalling in medium conditioned by ex vivo human serum. Furthermore, the functionality of the model was demonstrated by comparison of the response to medium conditioned by Fasted and Fed ex vivo human serum. [ABSTRACT FROM AUTHOR]

The aim of this study was to test the effects of two disparate isonitrogenous, isocaloric pre-exercise feeds on deuterium-oxide (D2O) derived measures of myofibrillar protein synthesis (myoPS) in humans. Methods: In a double-blind parallel group design, 22 resistance-trained men aged 18 to 35 years ingested a meal (6 kcal·kg−1, 0.8 g·kg−1 carbohydrate, 0.2 g·kg−1 fat) with 0.33 g·kg−1 nonessential amino acids blend (NEAA) or whey protein (WHEY), prior to resistance exercise (70% 1RM back-squats, 10 reps per set to failure, 25% duty cycle). Biopsies of M. vastus lateralis were obtained pre-ingestion (PRE) and +3 h post-exercise (POST). The myofibrillar fractional synthetic rate (myoFSR) was calculated via deuterium labelling of myofibrillar-bound alanine, measured by gas chromatography–pyrolysis–isotope ratio mass spectrometry (GC-Pyr-IRMS). Data are a mean percentage change (95% CI). Results: There was no discernable change in myoFSR following NEAA (10(−5, 25) %, p = 0.235), whereas an increase in myoFSR was observed after WHEY (28 (13, 43) %, p = 0.003). Conclusions: Measured by a D2O tracer technique, a disparate myoPS response was observed between NEAA and WHEY. Pre-exercise ingestion of whey protein increased post-exercise myoPS, whereas a NEAA blend did not, supporting the use of NEAA as a viable isonitrogenous negative control. [ABSTRACT FROM AUTHOR]