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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.


Effects of PA with or without the co-ingestion of WPC on 3 h post-feeding MPS. Legend: Data are presented as means ± standard error, and 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, PA, WPC, and PA + WPC n-sizes = 6–8. Panel a: Effects of each treatment on 3 h post-feeding MPS levels. Panel b: Representative image of the SUnSET blot. PA, WPC, and PA + WPC all significantly increased MPS levels compared to fasting conditions
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Fig3: Effects of PA with or without the co-ingestion of WPC on 3 h post-feeding MPS. Legend: Data are presented as means ± standard error, and 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, PA, WPC, and PA + WPC n-sizes = 6–8. Panel a: Effects of each treatment on 3 h post-feeding MPS levels. Panel b: Representative image of the SUnSET blot. PA, WPC, and PA + WPC all significantly increased MPS levels compared to fasting conditions

Mentions: Of note, WPC rats have been used in a prior study whereby we reported the significant two-fold increase in MPS relative to CON [22]. However, in the current study samples were re-run and normalized to Ponceau staining instead of beta-actin normalization given that mixed gastrocnemius fiber types may potentially yield varying normalization values. As expected, WPC robustly increased MPS levels compared to CON rats confirming our prior data. Compared to CON rats, MPS trended to be higher in PA-fed rats (p = 0.08; Fig. 3). Interestingly, however, PA + WPC-fed rats exhibited lower MPS levels compared to WPC-fed rats (p < 0.05, Fig. 3).Fig. 3


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 3 h post-feeding MPS. Legend: Data are presented as means ± standard error, and 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, PA, WPC, and PA + WPC n-sizes = 6–8. Panel a: Effects of each treatment on 3 h post-feeding MPS levels. Panel b: Representative image of the SUnSET blot. PA, WPC, and PA + WPC all significantly increased MPS levels compared to fasting conditions
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Fig3: Effects of PA with or without the co-ingestion of WPC on 3 h post-feeding MPS. Legend: Data are presented as means ± standard error, and 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, PA, WPC, and PA + WPC n-sizes = 6–8. Panel a: Effects of each treatment on 3 h post-feeding MPS levels. Panel b: Representative image of the SUnSET blot. PA, WPC, and PA + WPC all significantly increased MPS levels compared to fasting conditions
Mentions: Of note, WPC rats have been used in a prior study whereby we reported the significant two-fold increase in MPS relative to CON [22]. However, in the current study samples were re-run and normalized to Ponceau staining instead of beta-actin normalization given that mixed gastrocnemius fiber types may potentially yield varying normalization values. As expected, WPC robustly increased MPS levels compared to CON rats confirming our prior data. Compared to CON rats, MPS trended to be higher in PA-fed rats (p = 0.08; Fig. 3). Interestingly, however, PA + WPC-fed rats exhibited lower MPS levels compared to WPC-fed rats (p < 0.05, Fig. 3).Fig. 3

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.