Synergistic effects of citrulline supplementation and exercise on performance in male rats: evidence for implication of protein and energy metabolisms

2017 ◽  
Vol 131 (8) ◽  
pp. 775-790 ◽  
Author(s):  
Arthur Goron ◽  
Frédéric Lamarche ◽  
Valérie Cunin ◽  
Hervé Dubouchaud ◽  
Christophe Hourdé ◽  
...  
Keyword(s):  
Body Composition ◽  
Protein Synthesis ◽  
Endurance Training ◽  
Protein Metabolism ◽  
Muscle Protein ◽  
Synergistic Effects ◽  
Male Rats ◽  
Healthy Male ◽  
Proteomic Approach ◽  
Muscle Protein Metabolism

Background: Exercise and citrulline (CIT) are both regulators of muscle protein metabolism. However, the combination of both has been under-studied yet may have synergistic effects on muscle metabolism and performance. Methods: Three-month-old healthy male rats were randomly assigned to be fed ad libitum for 4 weeks with either a citrulline-enriched diet (1 g·kg−1·day−1) (CIT) or an isonitrogenous standard diet (by addition of nonessential amino acid) (Ctrl) and trained (running on treadmill 5 days·week−1) (ex) or not. Maximal endurance activity and body composition were assessed, and muscle protein metabolism (protein synthesis, proteomic approach) and energy metabolism [energy expenditure, mitochondrial metabolism] were explored. Results: Body composition was affected by exercise but not by CIT supplementation. Endurance training was associated with a higher maximal endurance capacity than sedentary groups (P<0.001), and running time was 14% higher in the CITex group than the Ctrlex group (139±4 min versus 122±6 min, P<0.05). Both endurance training and CIT supplementation alone increased muscle protein synthesis (by +27% and +33%, respectively, versus Ctrl, P<0.05) with an additive effect (+48% versus Ctrl, P<0.05). Mitochondrial metabolism was modulated by exercise but not directly by CIT supplementation. However, the proteomic approach demonstrated that CIT supplementation was able to affect energy metabolism, probably due to activation of pathways generating acetyl-CoA. Conclusion: CIT supplementation and endurance training in healthy male rats modulates both muscle protein and energy metabolisms, with synergic effects on an array of parameters, including performance and protein synthesis.

scholarly journals Glucocorticoid effects on insulin- and IGF-I-regulated muscle protein metabolism during aging

1998 ◽  
Vol 156 (1) ◽  
pp. 83-89 ◽  
Author(s):  
D Dardevet ◽  
C Sornet ◽  
I Savary ◽  
E Debras ◽  
P Patureau-Mirand ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Muscle Atrophy ◽  
Protein Metabolism ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Recovery Period ◽  
Adult Rats ◽  
Igf I ◽  
Muscle Protein Metabolism ◽  
Old Rats

This study was performed to assess the effect of glucocorticoids (dexamethasone) on insulin- and IGF-I-regulated muscle protein metabolism in adult and old rats. Muscle atrophy occurred more rapidly in old rats, and recovery of muscle mass was impaired when compared with adults. Muscle wasting resulted mainly from increased protein breakdown in adult rat but from depressed protein synthesis in the aged animal. Glucocorticoid treatment significantly decreased the stimulatory effect of insulin and IGF-I on muscle protein synthesis in adult rats by 25.9 and 58.1% respectively. In old rats, this effect was even greater, being 49.3 and 100% respectively. With regard to muscle proteolysis, glucocorticoids blunted the anti-proteolytic action of insulin and IGF-I in both age groups. During the recovery period, adult rats reversed the glucocorticoid-induced resistance of muscle protein metabolism within 3 days, at which time old rats still exhibited the decrease in insulin-regulated proteolysis. In conclusion, the higher sensitivity of old rat muscle to glucocorticoids may in part result from the greater modification of the effects of insulin and IGF-I on muscle protein metabolism. These responses to glucocorticoids in old rats may be associated with the emergence of muscle atrophy with advancing age.

Age and aerobic exercise training effects on whole body and muscle protein metabolism

2004 ◽  
Vol 286 (1) ◽  
pp. E92-E101 ◽  
Author(s):  
Kevin R. Short ◽  
Janet L. Vittone ◽  
Maureen L. Bigelow ◽  
David N. Proctor ◽  
K. Sreekumaran Nair
Keyword(s):  
Protein Synthesis ◽  
Exercise Training ◽  
Protein Metabolism ◽  
Protein Turnover ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Fat Free Mass ◽  
Whole Body ◽  
Men And Women ◽  
Muscle Protein Metabolism

Aging in humans is associated with loss of lean body mass, but the causes are incompletely defined. Lean tissue mass and function depend on continuous rebuilding of proteins. We tested the hypotheses that whole body and mixed muscle protein metabolism declines with age in men and women and that aerobic exercise training would partly reverse this decline. Seventy-eight healthy, previously untrained men and women aged 19-87 yr were studied before and after 4 mo of bicycle training (up to 45 min at 80% peak heart rate, 3-4 days/wk) or control (flexibility) activity. At the whole body level, protein breakdown (measured as [13C]leucine and [15N]phenylalanine flux), Leu oxidation, and protein synthesis (nonoxidative Leu disposal) declined with age at a rate of 4-5% per decade ( P < 0.001). Fat-free mass was closely correlated with protein turnover and declined 3% per decade ( P < 0.001), but even after covariate adjustment for fat-free mass, the decline in protein turnover with age remained significant. There were no differences between men and women after adjustment for fat-free mass. Mixed muscle protein synthesis also declined with age 3.5% per decade ( P < 0.05). Exercise training improved aerobic capacity 9% overall ( P < 0.01), and mixed muscle protein synthesis increased 22% ( P < 0.05), with no effect of age on the training response for either variable. Fat-free mass, whole body protein turnover, and resting metabolic rate were unchanged by training. We conclude that rates of whole body and muscle protein metabolism decline with age in men and women, thus indicating that there is a progressive decline in the body's remodeling processes with aging. This study also demonstrates that aerobic exercise can enhance muscle protein synthesis irrespective of age.

Muscle protein metabolism in female swimmers after a combination of resistance and endurance exercise

1996 ◽  
Vol 81 (5) ◽  
pp. 2034-2038 ◽  
Author(s):  
Kevin D. Tipton ◽  
Arny A. Ferrando ◽  
Bradley D. Williams ◽  
Robert R. Wolfe
Keyword(s):  
Protein Synthesis ◽  
Resistance Training ◽  
Endurance Exercise ◽  
Protein Metabolism ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Whole Body ◽  
Protein Breakdown ◽  
Body Protein ◽  
Muscle Protein Metabolism

Tipton, Kevin D., Arny A. Ferrando, Bradley D. Williams, and Robert R. Wolfe. Muscle protein metabolism in female swimmers after a combination of resistance and endurance exercise. J. Appl. Physiol. 81(5): 2034–2038, 1996.—There is little known about the responses of muscle protein metabolism in women to exercise. Furthermore, the effect of adding resistance training to an endurance training regimen on net protein anabolism has not been established in either men or women. The purpose of this study was to quantify the acute effects of combined swimming and resistance training on protein metabolism in female swimmers by the direct measurement of muscle protein synthesis and whole body protein degradation. Seven collegiate female swimmers were each studied on four separate occasions with a primed constant infusion of ring-[13C6]phenylalanine (Phe) to measure the fractional synthetic rate (FSR) of the posterior deltoid and whole body protein breakdown. Measurements were made over a 5-h period at rest and after each of three randomly ordered workouts: 1) 4,600 m of intense interval swimming (SW); 2) a whole body resistance-training workout with no swimming on that day (RW); and 3) swimming and resistance training combined (SR). Whole body protein breakdown was similar for all treatments (0.75 ± 0.04, 0.69 ± 0.03, 0.69 ± 0.02, and 0.71 ± 0.04 μmol ⋅ min−1 ⋅ kg−1for rest, RW, SW, and SR, respectively). The FSR of the posterior deltoid was significantly greater ( P< 0.05) after SR (0.082 ± 0.015%/h) than at rest (0.045 ± 0.006%/h). There was no significant difference in the FSR after RW (0.048 ± 0.004%/h) or SW (0.064 ± 0.008%/h) from rest or from SR. These data indicate that the combination of swimming and resistance exercise stimulates net muscle protein synthesis above resting levels in female swimmers.

Interleukin-1 receptor antagonist prevents sepsis-induced inhibition of protein synthesis

1994 ◽  
Vol 267 (5) ◽  
pp. E636-E641 ◽  
Author(s):  
R. Cooney ◽  
E. Owens ◽  
C. Jurasinski ◽  
K. Gray ◽  
J. Vannice ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Receptor Antagonist ◽  
Protein Metabolism ◽  
Muscle Protein ◽  
Interleukin 1 ◽  
Skeletal Muscle Protein ◽  
Inhibition Of Protein Synthesis ◽  
Muscle Protein Metabolism

To understand the role of interleukin-1 (IL-1) as a mediator of the sepsis-induced skeletal muscle catabolism, we investigated the effects of a specific IL-1 receptor antagonist (IL-1ra) on skeletal muscle protein metabolism in a rodent model of chronic abdominal sepsis. A constant infusion of IL-1ra (2 mg.kg-1.h-1) or saline was begun immediately after the induction of sepsis and continued for 5 days. The effect of IL-1ra on protein metabolism was examined in individual muscles (gastrocnemius, soleus, heart) containing different fiber types. Infusion of IL-1ra in control animals did not alter protein metabolism in any of the muscles examined. Muscle weight, protein content, and the rate of protein synthesis in gastrocnemius were reduced by sepsis, whereas none of these parameters were affected in soleus or heart. Infusion of IL-1ra prevented the sepsis-induced loss of muscle protein and inhibition of protein synthesis in gastrocnemius but was without effect in soleus or heart. IL-1ra infusion restored translational efficiency in the gastrocnemius of septic rats and was without effect on the RNA content. These results provide evidence for a role of IL-1 as a mediator of the sepsis-induced abnormalities in skeletal muscle protein metabolism.

Anabolic resistance: the effects of aging, sexual dimorphism, and immobilization on human muscle protein turnoverThis paper is one of a selection of papers published in this Special Issue, entitled 14th International Biochemistry of Exercise Conference – Muscles as Molecular and Metabolic Machines, and has undergone the Journal’s usual peer review process.

2009 ◽  
Vol 34 (3) ◽  
pp. 377-381 ◽  
Author(s):  
Michael J. Rennie
Keyword(s):  
Protein Synthesis ◽  
Protein Metabolism ◽  
Older Persons ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Response Relationship ◽  
Dose Response Relationship ◽  
Anabolic Resistance ◽  
Muscle Protein Metabolism ◽  
The Right

In healthy active older persons, there is no derangement of muscle protein metabolism. However, there is a major deficit in the ability of older muscles to regulate their maintenance during feeding and exercise. The dose–response relationship between myofibrillar protein synthesis and the availability of essential amino acids (EAA) is shifted down and to the right, and giving extra amino acids is unable to overcome this. There is no sex difference in basal or fed muscle protein metabolism in the young, but postmenopausal women have a greater anabolic resistance than older men. Anabolic resistance is also shown by the decreased phosphorylation in the PKB–mTOR–eIF4BP1 pathway in response to increased EAA. The muscle synthetic system is refractory to EAA provision, irrespective of the availability of insulin, insulin-like growth factor 1, and growth hormone. However, insulin is a major regulator of muscle protein breakdown, and there is a blunting of the ability of older muscle to decrease proteolysis in response to low concentrations of insulin, such as those observed after a light breakfast. Providing more EAA seems not to be useful, and modern N-balance data confirm that the dietary protein requirements of older persons are not increased. The sigmoidal dose–response relationship between muscle protein synthesis and resistance exercise intensity is shifted downward and to the right in older men. Decreased physical activity itself, even in young subjects, can produce anabolic resistance of muscle protein synthesis, which cannot be overcome by increasing amino acid availability. Exercise may retune the amino acid and (or) insulin sensitivity of muscle in older people.

Epinephrine depletion exacerbates the fasting-induced protein breakdown in fast-twitch skeletal muscles

2013 ◽  
Vol 305 (12) ◽  
pp. E1483-E1494 ◽  
Author(s):  
Flávia A. Graça ◽  
Dawit A. P. Gonçalves ◽  
Wilian A. Silveira ◽  
Eduardo C. Lira ◽  
Valéria Ernestânia Chaves ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Protein Metabolism ◽  
Skeletal Muscles ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Physiological Role ◽  
Protein Breakdown ◽  
Muscle Protein Metabolism ◽  
Fast Twitch ◽  
Fasted Rats

The physiological role of epinephrine in the regulation of skeletal muscle protein metabolism under fasting is unknown. We examined the effects of plasma epinephrine depletion, induced by adrenodemedullation (ADMX), on muscle protein metabolism in fed and 2-day-fasted rats. In fed rats, ADMX for 10 days reduced muscle mass, the cross-sectional area of extensor digitorum longus (EDL) muscle fibers, and the phosphorylation levels of Akt. In addition, ADMX led to a compensatory increase in muscle sympathetic activity, as estimated by the rate of norepinephrine turnover; this increase was accompanied by high rates of muscle protein synthesis. In fasted rats, ADMX exacerbated fasting-induced proteolysis in EDL but did not affect the low rates of protein synthesis. Accordingly, ADMX activated lysosomal proteolysis and further increased the activity of the ubiquitin (Ub)-proteasome system (UPS). Moreover, expression of the atrophy-related Ub ligases atrogin-1 and MuRF1 and the autophagy-related genes LC3b and GABARAPl1 were upregulated in EDL muscles from ADMX-fasted rats compared with sham-fasted rats, and ADMX reduced cAMP levels and increased fasting-induced Akt dephosphorylation. Unlike that observed for EDL muscles, soleus muscle proteolysis and Akt phosphorylation levels were not affected by ADMX. In isolated EDL, epinephrine reduced the basal UPS activity and suppressed overall proteolysis and atrogin-1 and MuRF1 induction following fasting. These data suggest that epinephrine released from the adrenal medulla inhibits fasting-induced protein breakdown in fast-twitch skeletal muscles, and these antiproteolytic effects on the UPS and lysosomal system are apparently mediated through a cAMP-Akt-dependent pathway, which suppresses ubiquitination and autophagy.

Effects of the anabolic steroid stanozolol on growth and protein metabolism in the rat

1987 ◽  
Vol 114 (3) ◽  
pp. 373-381 ◽  
Author(s):  
P. C. Bates ◽  
L. F. Chew ◽  
D. J. Millward
Keyword(s):  
Protein Synthesis ◽  
Anabolic Steroid ◽  
Protein Metabolism ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Muscle Growth ◽  
Female Rats ◽  
Male Rats ◽  
Anabolic Action ◽  
Rna Concentration

ABSTRACT The effects of the anabolic steroid stanozolol on whole body and muscle growth and protein metabolism in the rat have been examined. No responses could be found in normal well-fed male rats. Female rats responded to 1 mg/kg per day with an increased body and skeletal muscle growth rate and an increase in muscle protein synthesis. The anabolic action on muscle protein synthesis was due to increased RNA concentration with no change in the rate of protein synthesis per unit RNA (KRNA). Investigation of any anticatabolic effects of stanozolol treatment in male rats deprived of food for 24 h indicated no response of protein balance and turnover. However, rats treated with catabolic doses of corticosterone (50 mg/kg per day) did respond to stanozolol with decreased muscle growth inhibition due to better-maintained muscle protein synthesis. The latter response was due to a reversal of the corticosterone-induced reduction of KRNA, but with no effect on RNA concentration. Thus there appear to be at least two effects of stanozolol; an anabolic action evident only in female rats, involving increased muscle RNA concentrations, and an anticatabolic action involving inhibition of the corticosterone-induced fall in muscle RNA activity. In both cases, stanozolol influenced muscle protein synthesis with no evident effects on protein degradation. J. Endocr. (1987) 114, 373–381

The Effect of Feeding during Recovery from Aerobic Exercise on Skeletal Muscle Intracellular Signaling

2014 ◽  
Vol 24 (1) ◽  
pp. 70-78 ◽  
Author(s):  
Paul T. Reidy ◽  
Adam R. Konopka ◽  
J. Matthew Hinkley ◽  
Miranda K. Suer ◽  
Matthew P. Harber
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Aerobic Exercise ◽  
P38 Mapk ◽  
Protein Metabolism ◽  
Intracellular Signaling ◽  
Muscle Protein ◽  
Mapk Signaling ◽  
Skeletal Muscle Protein ◽  
Muscle Protein Metabolism

We previously reported an increase in skeletal muscle protein synthesis during fasted and fed recovery from nonexhaustive aerobic exercise (Harber et al., 2010). The current study examined skeletal muscle intracellular signaling in the same subjects to further investigate mechanisms of skeletal muscle protein metabolism with and without feeding following aerobic exercise. Eight males (VO2peak: 52 ± 2 ml−1.kg−1.min−1) performed 60-min of cycle ergometry at 72 ± 1% VO2peak on two occasions in a counter-balanced design. Exercise trials differed only in the postexercise nutritional intervention: EX-FED (5kcal, 0.83g carbohydrate, 0.37g protein, 0.03g fat per kg body weight) and EX-FAST (noncaloric, isovolumic placebo) ingested immediately and one hour after exercise. Muscle biopsies were obtained from the vastus lateralis at rest (on a separate day) and two hours postexercise to assess intracellular signaling via western blotting of p70S6K1, eEF2, 4EBP1, AMPKα and p38 MAPK. p70S6K1 phosphorylation was elevated (p < .05) in EX-FED relative to REST and EX-FAST. eEF2, 4EBP1, AMPKα and p38 MAPK signaling were unaltered at 2h after exercise independent of feeding status when expressed as the ratio of phosphorylated to total protein normalized to actin. These data demonstrate that feeding after a nonexhaustive bout of aerobic exercise stimulates skeletal muscle p70S6K1 intracellular signaling favorable for promoting protein synthesis which may, as recent literature has suggested, better prepare the muscle for subsequent exercise bouts. These data provide further support into the role of feeding on mechanisms regulating muscle protein metabolism during recovery from aerobic exercise.

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