Androgen receptors and testosterone in men—Effects of protein ingestion, resistance exercise and fiber type

Hulmi, Juha J.; Ahtiainen, Juha P.; Selänne, Harri; Volek, Jeff S.; Häkkinen, Keijo; Kovanen, Vuokko; Mero, Antti

doi:10.1016/j.jsbmb.2008.03.030

Cited by 38 publications

(38 citation statements)

References 57 publications

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“…Whey protein also seemed to prevent the elevation in serum total testosterone seen in the placebo group after the bout of RE, thereby supporting the previous results of protein ingestion (4,20,23). The testosterone response may be due to a decrease in the synthesis/secretion of testosterone and/or an increase in metabolic clearance.…”

Section: Muscle Hypertrophy After Rt and Myostatinsupporting

confidence: 80%

Resistance exercise with whey protein ingestion affects mTOR signaling pathway and myostatin in men

Hulmi¹,

Tannerstedt²,

Selänne³

et al. 2009

Journal of Applied Physiology

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120

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Hulmi JJ, Tannerstedt J, Selä nne H, Kainulainen H, Kovanen V, Mero AA. Resistance exercise with whey protein ingestion affects mTOR signaling pathway and myostatin in men. J Appl Physiol 106: 1720 -1729. First published March 19, 2009 doi:10.1152/japplphysiol.00087.2009.-Signaling pathways sense local and systemic signals and regulate muscle hypertrophy. The effects of whey protein ingestion on acute and long-term signaling responses of resistance exercise are not well known. Previously untrained young men were randomized into protein (n ϭ 9), placebo (n ϭ 9), and control (n ϭ 11) groups. Vastus lateralis (VL) muscle biopsies were taken before and 1 h and 48 h after a leg press of 5 ϫ 10 repetitions [resistance exercise (RE)] and after 21 wk (2 times per week) of resistance training (RT). Protein (15 g of whey) or nonenergetic placebo was ingested before and after a single RE bout and each RE workout throughout the RT. The protein group increased its body mass and VL muscle thickness (measured by ultrasonography) already at week 10.5 (P Ͻ 0.05). At week 21, the protein and placebo groups had similarly increased their myofiber size. No changes were observed in the nonexercised controls. However, the phosphorylation of p70 S6K and ribosomal protein S6 (rpS6) were increased at 1 h post-RE measured by Western blotting, the former being the greatest with protein ingestion. Mammalian target of rapamycin (mTOR) phosphorylation was increased after the RE bout and RT only in the protein group, whereas the protein ingestion prevented the post-RE decrease in phosphorylated eukaryotic initiation factor 4E binding protein 1 (p-4E-BP1). Akt phosphorylation decreased after RT, whereas no change was observed in phosphorylated eukaryotic elongation factor 2. A post-RE decrease in muscle myostatin protein occurred only in the placebo group. The results indicate that resistance exercise rapidly increases mTOR signaling and may decrease myostatin protein expression in muscle and that whey protein increases and prolongs the mTOR signaling response.hypertrophy; training; nutrition; S6K1; skeletal muscle ADEQUATE MUSCLE MASS is crucial for human well-being. It is, therefore, important to identify the mechanisms that stimulate muscle hypertrophy or prevent atrophy. The most efficient way to increase the size of a skeletal muscle is by resistance training (RT) in combination with protein-containing nutrition. Muscle hypertrophy due to RT and protein nutrition seems largely to result from cumulative acute increases in muscle protein synthesis. One resistance exercise (RE) bout can within 1 h increase muscle protein synthesis (9), which can last up to 72 h after exercise (39). Protein ingestion before or after a bout of RE has been shown to significantly enhance this response (52) and be possibly more beneficial in terms of muscle hypertrophy than nutrient ingestion at other times of day (7, 11). It would thus be important to understand how protein ingestion affects pathways regulating intracellular hypertrophy of muscle in the context ...

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Section: Muscle Hypertrophy After Rt and Myostatinsupporting

confidence: 80%

Resistance exercise with whey protein ingestion affects mTOR signaling pathway and myostatin in men

Hulmi¹,

Tannerstedt²,

Selänne³

et al. 2009

Journal of Applied Physiology

Self Cite

120

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“…Androgen receptor mRNA and protein have been observed to increase after 1-3 strength training sessions where levels of serum testosterone was acutely elevated (Bamman et al 2001;Willoughby and Taylor 2004;Hulmi et al 2008;Spiering et al 2009). Furthermore, administration of testosterone (without strength training) increases the content of androgen receptors in animal muscles (Carson et al 2002;Lee et al 2003) and humans (Ferrando et al 2002).…”

Section: Discussionmentioning

confidence: 99%

Physiological elevation of endogenous hormones results in superior strength training adaptation

Rønnestad¹,

Nygaard²,

Raastad

2011

Eur J Appl Physiol

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This file was dowloaded from the institutional repository Brage NIH -brage.bibsys.no/nih Rønnestad, B. R., Nygaard, H., Raastad, T. (2011) ABSTRACTThe purpose of this study was to determine the influence of transiently elevated endogenous hormone concentrations during exercise on strength training adaptations. Nine subjects performed four unilateral strength training session per week on the elbow flexors for 11 weeks. During two of the weekly sessions, leg exercises were performed to acutely increase the systemic anabolic hormone concentration immediately before the exercises for one of the elbow flexors (L+A). On the two other weekly training sessions, the contralateral elbow flexors were trained without prior leg exercises (A). By randomizing one arm of the subjects to serve as a control and the other as experimental, both conditions have the same nutritional and genetic environment. Serum testosterone and growth hormone was significantly increased during the L+A training session, while no hormonal changes occurred in the A session. Both A and L+A increased 1RM in biceps curl, peak power in elbow flexors at 30% and 60% of 1RM, and muscle volume of the elbow flexors (p<0.05). However, only L+A achieved increase in CSA at the part of the arm flexors with largest cross sectional area (p<0.001), while no changes occurred in A. L+A had superior relative improvement in 1RM biceps curl and favorable muscle adaptations in elbow flexors compared to A (p<0.05). In conclusion, performing leg exercises prior to arm exercises, and thereby increasing the levels of serum testosterone and growth hormone, induced superior strength training adaptations compared to arm training without acute elevation of hormones.

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“…material, see www.karger.com/doi/10.1159/000/499826). We examined the effect of AR on types of muscle fiber because the androgen/AR pathway has been shown to play important roles in determining the ratios of muscle fiber types [25]. In our EPS model, expression of myosin heavy chain (MHC) I, a slow type of MHC, was significantly increased.…”

Section: Resultsmentioning

confidence: 99%

“…Conversely, myostatin infusion into mice led to a 33% decrease in body weight and a 35–50% decrease in muscle mass, whereas gene deletion or loss of function in myostatin is associated with a marked increase in muscle mass of mice or humans [19-23]. Furthermore, exogenous testosterone decreased muscle expression of myostatin in a dose-dependent manner [24] and castration increased its expression [25]. However, the molecular mechanism, especially the role of the androgen receptor (AR), is poorly understood.…”

Section: Introductionmentioning

confidence: 99%

Low-Intensity Exercise Suppresses CCAAT/Enhancer-Binding Protein δ/Myostatin Pathway Through Androgen Receptor in Muscle Cells

et al. 2019

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Background: Androgen production following exercise has been suggested to contribute anabolic actions of muscle. However, the underlying mechanisms of the androgen receptor (AR) in androgen’s action are still unclear. Objective: In the present study, we examined androgen/AR-mediated action in exercise, especially for the suppression of myostatin, a potent negative regulator of muscle mass. Methods: To examine the effects of exercise, we employed low-intensity exercise in mice and electric pulse stimulation (EPS) in C2C12 myotubes. Androgen production by C2C12 myotubes was measured by enzyme-linked immunosorbent assay. To block the action of AR, we pretreated C2C12 myotubes with flutamide. Quantitative real-time polymerase chain reaction was used to determine the expression levels of proteolytic genes including CCAAT/enhancer-binding protein delta (C/EBPδ), myostatin and muscle E3 ubiquitin ligases, as well as myogenic genes such as myogenin and PGC1α. The activation of 5′-adenosine-activated protein kinase and STAT3 was determined by Western blot analysis. Results: Both mRNA and protein levels of AR significantly increased in skeletal muscle of low-intensity exercised mice and C2C12 myotubes exposed to EPS. Production of testosterone and dihydrotestosterone from EPS-treated C2C12 myotubes was markedly increased. Of interest, we found that myostatin was clearly inhibited by EPS, and its inhibition was significantly abrogated when AR was blocked by flutamide. To test how AR suppresses myostatin, we examined the effects of EPS on C/EBPδ because the promoter region of myostatin has several C/EBP recognition sites. C/EBPδ expression was decreased by EPS, and this decrease was negated by flutamide. IL-6 and phospho-STAT3 (pSTAT3) expression, the downstream pathway of myostatin, were decreased by EPS and this was also reversed by flutamide. Similar downregulation of C/EBPδ, myostatin, and IL-6 was seen in skeletal muscle of low-intensity exercised mice. Conclusions: Muscle AR expression and androgen production were increased by exercise and EPS treatment. As a mechanistical insight, it is suggested that AR inhibited myostatin expression transcriptionally by C/EBPδ suppression, which negatively influences IL-6/pSTAT3 expression and consequently contributes to the prevention of muscle proteolysis during exercise.

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Androgen receptors and testosterone in men—Effects of protein ingestion, resistance exercise and fiber type

Cited by 38 publications

References 57 publications

Resistance exercise with whey protein ingestion affects mTOR signaling pathway and myostatin in men

Resistance exercise with whey protein ingestion affects mTOR signaling pathway and myostatin in men

Physiological elevation of endogenous hormones results in superior strength training adaptation

Low-Intensity Exercise Suppresses CCAAT/Enhancer-Binding Protein δ/Myostatin Pathway Through Androgen Receptor in Muscle Cells

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