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Effects of oral phosphatidic acid feeding with or without whey protein on muscle protein synthesis and anabolic signaling in rodent skeletal muscle.

Mobley CB, Hornberger TA, Fox CD, Healy JC, Ferguson BS, Lowery RP, McNally RM, Lockwood CM, Stout JR, Kavazis AN, Wilson JM, Roberts MD - J Int Soc Sports Nutr (2015)

Bottom Line: Three hours post-feeding, gastrocnemius muscle was removed for markers of Akt-mTOR signaling, gene expression patterns related to skeletal muscle mass regulation and metabolism, and MPS analysis via the SUnSET method.C2C12 myoblast data agreed with the in vivo data herein showing that PA increased MPS levels 51% (p < 0.001) phosphorylated p70s6k (Thr389) levels 67% (p < 0.001).Our results are the first in vivo evidence to demonstrate that PA tends to increases MPS 3 h post-feeding, though PA may delay WPC-mediated MPS kinetics within a 3 h post-feeding window.

View Article: PubMed Central - PubMed

Affiliation: School of Kinesiology, Auburn University, Auburn, AL USA.

ABSTRACT

Background: Phosphatidic acid (PA) is a diacyl-glycerophospholipid that acts as a signaling molecule in numerous cellular processes. Recently, PA has been proposed to stimulate skeletal muscle protein accretion, but mechanistic studies are lacking. Furthermore, it is unknown whether co-ingesting PA with other leucine-containing ingredients can enhance intramuscular anabolic signaling mechanisms. Thus, the purpose of this study was to examine if oral PA feeding acutely increases anabolic signaling markers and muscle protein synthesis (MPS) in gastrocnemius with and without whey protein concentrate (WPC).

Methods: Overnight fasted male Wistar rats (~250 g) were randomly assigned to four groups: control (CON, n = 6-13), PA (29 mg; n = 8), WPC (197 mg; n = 8), or PA + WPC (n = 8). Three hours post-feeding, gastrocnemius muscle was removed for markers of Akt-mTOR signaling, gene expression patterns related to skeletal muscle mass regulation and metabolism, and MPS analysis via the SUnSET method.

Results: Compared to CON rats, PA, WPC and PA + WPC resulted in a significant elevation in the phosphorylation of mTOR (Ser2481) and rps6 (Ser235/236) (p < 0.05) in the gastrocnemius though there were no differences between the supplemented groups. MPS levels in the gastrocnemius were significantly (p < 0.05) elevated in WPC versus CON rats, and tended to be elevated in PA versus CON rats (p = 0.08), though MPS was less in PA + WPC versus WPC rats (p < 0.05) in spite of robust increases in mTOR pathway activity markers in the former group. C2C12 myoblast data agreed with the in vivo data herein showing that PA increased MPS levels 51% (p < 0.001) phosphorylated p70s6k (Thr389) levels 67% (p < 0.001).

Conclusions: Our results are the first in vivo evidence to demonstrate that PA tends to increases MPS 3 h post-feeding, though PA may delay WPC-mediated MPS kinetics within a 3 h post-feeding window.

No MeSH data available.


PA increases C2C12 myoblast mTOR signaling and MPS. Legend: Data are presented as means ± standard error. All data were obtained from 2–3 independent experiments (n = 6–11 wells per condition). Significant between-treatment differences (p < 0.001) existed for p-p70s6k (Thr389) and MPS levels as determined by independent samples t-tests (denoted by different superscript letters). Panel a: C2C12 myoblasts were serum starved for 18 h and then stimulated for 30 min with 30 μM PA, or PBS as a control condition. Measurements of mTOR signaling were assessed by evaluating the phospho to total ratio (P:T) for p-p70s6k (Thr389) and total p70S6k. Panel b: C2C12 myoblasts were treated as described in panel a and measurements of protein synthesis were performed by assessing puromycin incorporation during the final 30 min of a 60 min stimulation period. The Western blot membranes were stained with Coomassie Blue to verify equal loading of protein in all lanes
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Fig4: PA increases C2C12 myoblast mTOR signaling and MPS. Legend: Data are presented as means ± standard error. All data were obtained from 2–3 independent experiments (n = 6–11 wells per condition). Significant between-treatment differences (p < 0.001) existed for p-p70s6k (Thr389) and MPS levels as determined by independent samples t-tests (denoted by different superscript letters). Panel a: C2C12 myoblasts were serum starved for 18 h and then stimulated for 30 min with 30 μM PA, or PBS as a control condition. Measurements of mTOR signaling were assessed by evaluating the phospho to total ratio (P:T) for p-p70s6k (Thr389) and total p70S6k. Panel b: C2C12 myoblasts were treated as described in panel a and measurements of protein synthesis were performed by assessing puromycin incorporation during the final 30 min of a 60 min stimulation period. The Western blot membranes were stained with Coomassie Blue to verify equal loading of protein in all lanes

Mentions: p-p70s6k (Thr389) increased 67 % in 30 min PA-treated myoblasts compared to the control condition (p < 0.001; Fig. 4a). Moreover, MPS levels were increased 51 % in 60 min PA-treated myoblasts compared to the control condition (p < 0.001; Fig. 4b). These data further validate the aforementioned in vivo results suggesting that the soy-derived PA studied herein increases mTOR signaling and likely increases MPS.Fig. 4


Effects of oral phosphatidic acid feeding with or without whey protein on muscle protein synthesis and anabolic signaling in rodent skeletal muscle.

Mobley CB, Hornberger TA, Fox CD, Healy JC, Ferguson BS, Lowery RP, McNally RM, Lockwood CM, Stout JR, Kavazis AN, Wilson JM, Roberts MD - J Int Soc Sports Nutr (2015)

PA increases C2C12 myoblast mTOR signaling and MPS. Legend: Data are presented as means ± standard error. All data were obtained from 2–3 independent experiments (n = 6–11 wells per condition). Significant between-treatment differences (p < 0.001) existed for p-p70s6k (Thr389) and MPS levels as determined by independent samples t-tests (denoted by different superscript letters). Panel a: C2C12 myoblasts were serum starved for 18 h and then stimulated for 30 min with 30 μM PA, or PBS as a control condition. Measurements of mTOR signaling were assessed by evaluating the phospho to total ratio (P:T) for p-p70s6k (Thr389) and total p70S6k. Panel b: C2C12 myoblasts were treated as described in panel a and measurements of protein synthesis were performed by assessing puromycin incorporation during the final 30 min of a 60 min stimulation period. The Western blot membranes were stained with Coomassie Blue to verify equal loading of protein in all lanes
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4537536&req=5

Fig4: PA increases C2C12 myoblast mTOR signaling and MPS. Legend: Data are presented as means ± standard error. All data were obtained from 2–3 independent experiments (n = 6–11 wells per condition). Significant between-treatment differences (p < 0.001) existed for p-p70s6k (Thr389) and MPS levels as determined by independent samples t-tests (denoted by different superscript letters). Panel a: C2C12 myoblasts were serum starved for 18 h and then stimulated for 30 min with 30 μM PA, or PBS as a control condition. Measurements of mTOR signaling were assessed by evaluating the phospho to total ratio (P:T) for p-p70s6k (Thr389) and total p70S6k. Panel b: C2C12 myoblasts were treated as described in panel a and measurements of protein synthesis were performed by assessing puromycin incorporation during the final 30 min of a 60 min stimulation period. The Western blot membranes were stained with Coomassie Blue to verify equal loading of protein in all lanes
Mentions: p-p70s6k (Thr389) increased 67 % in 30 min PA-treated myoblasts compared to the control condition (p < 0.001; Fig. 4a). Moreover, MPS levels were increased 51 % in 60 min PA-treated myoblasts compared to the control condition (p < 0.001; Fig. 4b). These data further validate the aforementioned in vivo results suggesting that the soy-derived PA studied herein increases mTOR signaling and likely increases MPS.Fig. 4

Bottom Line: Three hours post-feeding, gastrocnemius muscle was removed for markers of Akt-mTOR signaling, gene expression patterns related to skeletal muscle mass regulation and metabolism, and MPS analysis via the SUnSET method.C2C12 myoblast data agreed with the in vivo data herein showing that PA increased MPS levels 51% (p < 0.001) phosphorylated p70s6k (Thr389) levels 67% (p < 0.001).Our results are the first in vivo evidence to demonstrate that PA tends to increases MPS 3 h post-feeding, though PA may delay WPC-mediated MPS kinetics within a 3 h post-feeding window.

View Article: PubMed Central - PubMed

Affiliation: School of Kinesiology, Auburn University, Auburn, AL USA.

ABSTRACT

Background: Phosphatidic acid (PA) is a diacyl-glycerophospholipid that acts as a signaling molecule in numerous cellular processes. Recently, PA has been proposed to stimulate skeletal muscle protein accretion, but mechanistic studies are lacking. Furthermore, it is unknown whether co-ingesting PA with other leucine-containing ingredients can enhance intramuscular anabolic signaling mechanisms. Thus, the purpose of this study was to examine if oral PA feeding acutely increases anabolic signaling markers and muscle protein synthesis (MPS) in gastrocnemius with and without whey protein concentrate (WPC).

Methods: Overnight fasted male Wistar rats (~250 g) were randomly assigned to four groups: control (CON, n = 6-13), PA (29 mg; n = 8), WPC (197 mg; n = 8), or PA + WPC (n = 8). Three hours post-feeding, gastrocnemius muscle was removed for markers of Akt-mTOR signaling, gene expression patterns related to skeletal muscle mass regulation and metabolism, and MPS analysis via the SUnSET method.

Results: Compared to CON rats, PA, WPC and PA + WPC resulted in a significant elevation in the phosphorylation of mTOR (Ser2481) and rps6 (Ser235/236) (p < 0.05) in the gastrocnemius though there were no differences between the supplemented groups. MPS levels in the gastrocnemius were significantly (p < 0.05) elevated in WPC versus CON rats, and tended to be elevated in PA versus CON rats (p = 0.08), though MPS was less in PA + WPC versus WPC rats (p < 0.05) in spite of robust increases in mTOR pathway activity markers in the former group. C2C12 myoblast data agreed with the in vivo data herein showing that PA increased MPS levels 51% (p < 0.001) phosphorylated p70s6k (Thr389) levels 67% (p < 0.001).

Conclusions: Our results are the first in vivo evidence to demonstrate that PA tends to increases MPS 3 h post-feeding, though PA may delay WPC-mediated MPS kinetics within a 3 h post-feeding window.

No MeSH data available.