Stimulation of muscle protein synthesis by whey and caseinate ingestion after resistance exercise in elderly individuals

The aim was to evaluate the role of insulin and insulin-like growth factor I (IGF-I) in activation of muscle protein synthesis after oral feeding. Synthesis rate of globular and myofibrillar proteins in muscle tissue was quantified by a flooding dose of radioactive phenylalanine. Muscle tissue expression of IGF-I mRNA was measured. Normal (C57 Bl) and diabetic mice (type I and type II) were subjected to an overnight fast (18 h) with subsequent refeeding procedures for 3 h with either oral chow intake or provision of insulin, IGF-I, glucose, and amino acids. Anti-insulin and anti-IGF-I were provided intraperitoneally before oral refeeding in some experiments. An overnight fast reduced synthesis of both globular (38 +/- 3%) and myofibrillar proteins (54 +/- 3%) in skeletal muscles, which was reversed by oral refeeding. Muscle protein synthesis, after starvation/ refeeding, was proportional and similar to changes in skeletal muscle IGF-I mRNA expression. Diabetic mice responded quantitatively similarly to starvation/refeeding in muscle protein synthesis compared with normal mice (C57 Bl). Both anti-insulin and anti-IGF-I attenuated significantly the stimulation of muscle protein synthesis in response to oral feeding, whereas exogenous provision of either insulin or IGF-I to overnight-starved and freely fed mice did not clearly stimulate protein synthesis in skeletal muscles. Our results support the suggestion that insulin and IGF-I either induce or facilitate the protein synthesis machinery in skeletal muscles rather than exerting a true stimulation of the biosynthetic process during feeding.

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The response of muscle protein synthesis following whole-body resistance exercise is greater following 40 g than 20 g of ingested whey protein

Physiological Reports ◽

10.14814/phy2.12893 ◽

2016 ◽

Vol 4 (15) ◽

pp. e12893 ◽

Cited By ~ 75

Author(s):

Lindsay S. Macnaughton ◽

Sophie L. Wardle ◽

Oliver C. Witard ◽

Chris McGlory ◽

D. Lee Hamilton ◽

...

Keyword(s):

Protein Synthesis ◽

Resistance Exercise ◽

Whey Protein ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Whole Body ◽

Body Resistance

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Resistance exercise maintains skeletal muscle protein synthesis during bed rest

Journal of Applied Physiology ◽

10.1152/jappl.1997.82.3.807 ◽

1997 ◽

Vol 82 (3) ◽

pp. 807-810 ◽

Cited By ~ 147

Author(s):

Arny A. Ferrando ◽

Kevin D. Tipton ◽

Marcas M. Bamman ◽

Robert R. Wolfe

Keyword(s):

Skeletal Muscle ◽

Protein Synthesis ◽

Resistance Training ◽

Resistance Exercise ◽

Lean Body Mass ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Bed Rest ◽

Skeletal Muscle Protein ◽

Skeletal Muscle Protein Synthesis

Ferrando, Arny A., Kevin D. Tipton, Marcas M. Bamman, and Robert R. Wolfe. Resistance exercise maintains skeletal muscle protein synthesis during bed rest. J. Appl. Physiol. 82(3): 807–810, 1997.—Spaceflight results in a loss of lean body mass and muscular strength. A ground-based model for microgravity, bed rest, results in a loss of lean body mass due to a decrease in muscle protein synthesis (MPS). Resistance training is suggested as a proposed countermeasure for spaceflight-induced atrophy because it is known to increase both MPS and skeletal muscle strength. We therefore hypothesized that scheduled resistance training throughout bed rest would ameliorate the decrease in MPS. Two groups of healthy volunteers were studied during 14 days of simulated microgravity. One group adhered to strict bed rest (BR; n = 5), whereas a second group engaged in leg resistance exercise every other day throughout bed rest (BREx; n = 6). MPS was determined directly by the incorporation of infusedl-[ ring-13C6]phenylalanine into vastus lateralis protein. After 14 days of bed rest, MPS in the BREx group did not change and was significantly greater than in the BR group. Thus moderate-resistance exercise can counteract the decrease in MPS during bed rest.

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Stimulation of Muscle Protein Synthesis by Prolonged Parenteral Infusion of Leucine Is Dependent on Amino Acid Availability in Neonatal Pigs

Journal of Nutrition ◽

10.3945/jn.109.113621 ◽

2009 ◽

Vol 140 (2) ◽

pp. 264-270 ◽

Cited By ~ 52

Author(s):

Fiona A. Wilson ◽

Agus Suryawan ◽

Maria C. Gazzaneo ◽

Renán A. Orellana ◽

Hanh V. Nguyen ◽

...

Keyword(s):

Protein Synthesis ◽

Amino Acid ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Neonatal Pigs ◽

Amino Acid Availability ◽

Stimulation Of

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Exercise May Promote Skeletal Muscle Hypertrophy via Enhancing Leucine-Sensing: Preliminary Evidence

Frontiers in Physiology ◽

10.3389/fphys.2021.741038 ◽

2021 ◽

Vol 12 ◽

Author(s):

Yan Zhao ◽

Jason Cholewa ◽

Huayu Shang ◽

Yueqin Yang ◽

Xiaomin Ding ◽

...

Keyword(s):

Protein Synthesis ◽

Resistance Exercise ◽

Aerobic Exercise ◽

Protein Concentration ◽

Muscle Hypertrophy ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Muscle Fibers ◽

Mtor Signaling ◽

Treadmill Running

Several studies have indicated a positive effect of exercise (especially resistance exercise) on the mTOR signaling that control muscle protein synthesis and muscle remodeling. However, the relationship between exercise, mTOR activation and leucine-sensing requires further clarification. Two month old Sprague-Dawley rats were subjected to aerobic exercise (treadmill running at 20 m/min, 6° incline for 60 min) and resistance exercise (incremental ladder climbing) for 4 weeks. The gastrocnemius muscles were removed for determination of muscle fibers diameter, cross-sectional area (CSA), protein concentration and proteins involved in muscle leucine-sensing and protein synthesis. The results show that 4 weeks of resistance exercise increased the diameter and CSA of gastrocnemius muscle fibers, protein concentration, the phosphorylation of mTOR (Ser2448), 4E-BP1(Thr37/46), p70S6K (Thr389), and the expression of LeuRS, while aerobic exercise just led to a significant increase in protein concentration and the phosphorylation of 4E-BP1(Thr37/46). Moreover, no difference was found for Sestrin2 expression between groups. The current study shows resistance exercise, but not aerobic exercise, may increase muscle protein synthesis and protein deposition, and induces muscle hypertrophy through LeuRS/mTOR signaling pathway. However, further studies are still warranted to clarify the exact effects of vary intensities and durations of aerobic exercise training.

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