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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.


Related in: MedlinePlus

Effects of PA with or without the co-ingestion of WPC on skeletal muscle mRNA expression patterns. Legend: Data are presented as means ± standard error. Bars not sharing similar superscript letters are significantly different (p < 0.05) as determined by one-way ANOVAs with protected LSD post hoc comparisons. CON n-size = 13, PA, WPC, and PA + WPC n-sizes = 7–8. Panels a & b: Genes linked to skeletal muscle hypertrophy. Panels c & d: Genes linked to skeletal muscle metabolism. Panels e & f: Genes linked to skeletal muscle atrophy (Atrogin-1) and remodeling (MuRF-1)
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Fig5: Effects of PA with or without the co-ingestion of WPC on skeletal muscle mRNA expression patterns. Legend: Data are presented as means ± standard error. Bars not sharing similar superscript letters are significantly different (p < 0.05) as determined by one-way ANOVAs with protected LSD post hoc comparisons. CON n-size = 13, PA, WPC, and PA + WPC n-sizes = 7–8. Panels a & b: Genes linked to skeletal muscle hypertrophy. Panels c & d: Genes linked to skeletal muscle metabolism. Panels e & f: Genes linked to skeletal muscle atrophy (Atrogin-1) and remodeling (MuRF-1)

Mentions: Beyond examining the effects that PA with or without WPC exhibited on mTOR signaling and MPS, we also were interested in prospectively exploring if these treatments acutely affected gene expression patterns related to skeletal muscle mass regulation and metabolism. Interestingly, PA or WPC did not cause a change in Mstn mRNA compared to CON, though PA + WPC rats presented statistically lower Mstn mRNA levels relative to the PA- and WPC-fed rats (p < 0.05; Fig. 5a); however, Mstn mRNA in WPC + PA did not change compared to the control group. Compared to CON, PA robustly increased p21Cip1 mRNA expression patterns over 5.6-fold (p < 0.05, Fig. 5b). Likewise, compared to CON, WPC and PA + WPC increased p21Cip1 mRNA expression over 3-fold, though this only tended to be greater than fasting (p < 0.10) due to the high post-feeding variation in this transcript. No between-group differences existed in PGC-1α mRNA levels (Fig. 5c). Compared to CON, PA increased Glut-4 mRNA levels 43 % (p < 0.05; Fig. 5d) and PA + WPC increased Glut-4 mRNA expression patterns ~60 % (p < 0.05, Fig. 5d). All treatments presented similar Atrogin-1 mRNA levels (Fig. 5e). Finally, PA + WPC increased MuRF-1 mRNA 2.3-fold relative to CON (p < 0.05, Fig. 5f).Fig. 5


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)

Effects of PA with or without the co-ingestion of WPC on skeletal muscle mRNA expression patterns. Legend: Data are presented as means ± standard error. Bars not sharing similar superscript letters are significantly different (p < 0.05) as determined by one-way ANOVAs with protected LSD post hoc comparisons. CON n-size = 13, PA, WPC, and PA + WPC n-sizes = 7–8. Panels a & b: Genes linked to skeletal muscle hypertrophy. Panels c & d: Genes linked to skeletal muscle metabolism. Panels e & f: Genes linked to skeletal muscle atrophy (Atrogin-1) and remodeling (MuRF-1)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4537536&req=5

Fig5: Effects of PA with or without the co-ingestion of WPC on skeletal muscle mRNA expression patterns. Legend: Data are presented as means ± standard error. Bars not sharing similar superscript letters are significantly different (p < 0.05) as determined by one-way ANOVAs with protected LSD post hoc comparisons. CON n-size = 13, PA, WPC, and PA + WPC n-sizes = 7–8. Panels a & b: Genes linked to skeletal muscle hypertrophy. Panels c & d: Genes linked to skeletal muscle metabolism. Panels e & f: Genes linked to skeletal muscle atrophy (Atrogin-1) and remodeling (MuRF-1)
Mentions: Beyond examining the effects that PA with or without WPC exhibited on mTOR signaling and MPS, we also were interested in prospectively exploring if these treatments acutely affected gene expression patterns related to skeletal muscle mass regulation and metabolism. Interestingly, PA or WPC did not cause a change in Mstn mRNA compared to CON, though PA + WPC rats presented statistically lower Mstn mRNA levels relative to the PA- and WPC-fed rats (p < 0.05; Fig. 5a); however, Mstn mRNA in WPC + PA did not change compared to the control group. Compared to CON, PA robustly increased p21Cip1 mRNA expression patterns over 5.6-fold (p < 0.05, Fig. 5b). Likewise, compared to CON, WPC and PA + WPC increased p21Cip1 mRNA expression over 3-fold, though this only tended to be greater than fasting (p < 0.10) due to the high post-feeding variation in this transcript. No between-group differences existed in PGC-1α mRNA levels (Fig. 5c). Compared to CON, PA increased Glut-4 mRNA levels 43 % (p < 0.05; Fig. 5d) and PA + WPC increased Glut-4 mRNA expression patterns ~60 % (p < 0.05, Fig. 5d). All treatments presented similar Atrogin-1 mRNA levels (Fig. 5e). Finally, PA + WPC increased MuRF-1 mRNA 2.3-fold relative to CON (p < 0.05, Fig. 5f).Fig. 5

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.


Related in: MedlinePlus