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Limited effect of over-the-counter doses of ibuprofen on mechanisms regulating muscle hypertrophy during resistance training in young adults.
Lilja, M, Moberg, M, Apró, W, Martínez-Aranda, LM, Rundqvist, H, Langlet, B, Gustafsson, T, Lundberg, TR
Journal of applied physiology (Bethesda, Md. : 1985). 2023;(3):753-765
Abstract
We have previously shown that maximal over-the-counter doses of ibuprofen, compared with low doses of acetylsalicylic acid, reduce muscle hypertrophy in young individuals after 8 wk of resistance training. Because the mechanism behind this effect has not been fully elucidated, we here investigated skeletal muscle molecular responses and myofiber adaptations in response to acute and chronic resistance training with concomitant drug intake. Thirty-one young (aged 18-35 yr) healthy men (n = 17) and women (n = 14) were randomized to receive either ibuprofen (IBU; 1,200 mg daily; n = 15) or acetylsalicylic acid (ASA; 75 mg daily; n = 16) while undergoing 8 wk of knee extension training. Muscle biopsies from the vastus lateralis were obtained before, at week 4 after an acute exercise session, and after 8 wk of resistance training and analyzed for mRNA markers and mTOR signaling, as well as quantification of total RNA content (marker of ribosome biogenesis) and immunohistochemical analysis of muscle fiber size, satellite cell content, myonuclear accretion, and capillarization. There were only two treatment × time interaction in selected molecular markers after acute exercise (atrogin-1 and MuRF1 mRNA), but several exercise effects. Muscle fiber size, satellite cell and myonuclear accretion, and capillarization were not affected by chronic training or drug intake. RNA content increased comparably (∼14%) in both groups. Collectively, these data suggest that established acute and chronic hypertrophy regulators (including mTOR signaling, ribosome biogenesis, satellite cell content, myonuclear accretion, and angiogenesis) were not differentially affected between groups and therefore do not explain the deleterious effects of ibuprofen on muscle hypertrophy in young adults.NEW & NOTEWORTHY Here we show that mTOR signaling, fiber size, ribosome biogenesis, satellite cell content, myonuclear accretion, and angiogenesis were not differentially affected between groups undergoing 8 wk of resistance training with concomitant anti-inflammatory medication (ibuprofen versus low-dose aspirin). Atrogin-1 and MuRF-1 mRNA were more downregulated after acute exercise in the low-dose aspirin group than in the ibuprofen group. Taken together it appears that these established hypertrophy regulators do not explain the previously reported deleterious effects of high doses of ibuprofen on muscle hypertrophy in young adults.
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Molecular Regulators of Muscle Mass and Mitochondrial Remodeling Are Not Influenced by Testosterone Administration in Young Women.
Horwath, O, Moberg, M, Hirschberg, AL, Ekblom, B, Apró, W
Frontiers in endocrinology. 2022;13:874748
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Plain language summary
Testosterone is a sex hormone normally found in higher amounts in adult males than females. Testosterone plays a number of important roles, including influencing muscle size and strength. Treatment with testosterone has been shown to increase lean mass and muscle strength in women as well as men. However, female-only studies are limited, and the precise mechanisms underlying these changes are not well understood. This randomised control trial examined the effect of testosterone administration on regulators of muscle protein turnover and mitochondrial function in muscle samples collected from young women. 48 healthy, pre-menopausal women were assigned to receive either 10mg of transdermal testosterone gel per day, or a placebo, for 10 weeks. Muscle samples were collected via biopsy before and after the intervention. Testosterone administration did not appear to have a significant effect on androgen receptors, 5-alpha reductase, anabolic signalling, or mitochondrial remodelling in muscle tissue. The researchers concluded that improvements in muscle size and oxidative capacity following testosterone administration cannot be explained by changes in protein expression related to muscle protein turnover or mitochondrial remodelling. The authors went on to suggest that the small sample size in this study may have reduced the ability to detect small but biologically relevant changes in protein levels. Within the research, there is large variability among studies in terms of sex, age, route of administration and length of treatment, which makes putting these findings into context of the wider literature difficult.
Abstract
Testosterone (T) administration has previously been shown to improve muscle size and oxidative capacity. However, the molecular mechanisms underlying these adaptations in human skeletal muscle remain to be determined. Here, we examined the effect of moderate-dose T administration on molecular regulators of muscle protein turnover and mitochondrial remodeling in muscle samples collected from young women. Forty-eight healthy, physically active, young women (28 ± 4 years) were assigned in a random double-blind fashion to receive either T (10 mg/day) or placebo for 10-weeks. Muscle biopsies collected before and after the intervention period were divided into sub-cellular fractions and total protein levels of molecular regulators of muscle protein turnover and mitochondrial remodeling were analyzed using Western blotting. T administration had no effect on androgen receptor or 5α-reductase levels, nor on proteins involved in the mTORC1-signaling pathway (mTOR, S6K1, eEF2 and RPS6). Neither did it affect the abundance of proteins associated with proteasomal protein degradation (MAFbx, MuRF-1 and UBR5) and autophagy-lysosomal degradation (AMPK, ULK1 and p62). T administration also had no effect on proteins in the mitochondria enriched fraction regulating mitophagy (Beclin, BNIP3, LC3B-I, LC3B-II and LC3B-II/I ratio) and morphology (Mitofilin), and it did not alter the expression of mitochondrial fission- (FIS1 and DRP1) or fusion factors (OPA1 and MFN2). In summary, these data indicate that improvements in muscle size and oxidative capacity in young women in response to moderate-dose T administration cannot be explained by alterations in total expression of molecular factors known to regulate muscle protein turnover or mitochondrial remodeling.
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Acute normobaric hypoxia blunts contraction-mediated mTORC1- and JNK-signaling in human skeletal muscle.
Moberg, M, Apró, W, Horwath, O, van Hall, G, Blackwood, SJ, Katz, A
Acta physiologica (Oxford, England). 2022;(2):e13771
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Abstract
AIM: Hypoxia has been shown to reduce resistance exercise-induced stimulation of protein synthesis and long-term gains in muscle mass. However, the mechanism whereby hypoxia exerts its effect is not clear. Here, we examine the effect of acute hypoxia on the activity of several signalling pathways involved in the regulation of muscle growth following a bout of resistance exercise. METHODS Eight men performed two sessions of leg resistance exercise in normoxia or hypoxia (12% O2 ) in a randomized crossover fashion. Muscle biopsies were obtained at rest and 0, 90,180 minutes after exercise. Muscle analyses included levels of signalling proteins and metabolites associated with energy turnover. RESULTS Exercise during normoxia induced a 5-10-fold increase of S6K1Thr389 phosphorylation throughout the recovery period, but hypoxia blunted the increases by ~50%. Phosphorylation of JNKThr183/Tyr185 and the JNK target SMAD2Ser245/250/255 was increased by 30- to 40-fold immediately after the exercise in normoxia, but hypoxia blocked almost 70% of the activation. Throughout recovery, phosphorylation of JNK and SMAD2 remained elevated following the exercise in normoxia, but the effect of hypoxia was lost at 90-180 minutes post-exercise. Hypoxia had no effect on exercise-induced Hippo or autophagy signalling and ubiquitin-proteasome related protein levels. Nor did hypoxia alter the changes induced by exercise in high-energy phosphates, glucose 6-P, lactate or phosphorylation of AMPK or ACC. CONCLUSION We conclude that acute severe hypoxia inhibits resistance exercise-induced mTORC1- and JNK signalling in human skeletal muscle, effects that do not appear to be mediated by changes in the degree of metabolic stress in the muscle.
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High-intensity leg cycling alters the molecular response to resistance exercise in the arm muscles.
Moberg, M, Apró, W, Cervenka, I, Ekblom, B, van Hall, G, Holmberg, HC, Ruas, JL, Blomstrand, E
Scientific reports. 2021;(1):6453
Abstract
This study examined acute molecular responses to concurrent exercise involving different muscles. Eight men participated in a randomized crossover-trial with two sessions, one where they performed interval cycling followed by upper body resistance exercise (ER-Arm), and one with upper body resistance exercise only (R-Arm). Biopsies were taken from the triceps prior to and immediately, 90- and 180-min following exercise. Immediately after resistance exercise, the elevation in S6K1 activity was smaller and the 4E-BP1:eIF4E interaction greater in ER-Arm, but this acute attenuation disappeared during recovery. The protein synthetic rate in triceps was greater following exercise than at rest, with no difference between trials. The level of PGC-1α1 mRNA increased to greater extent in ER-Arm than R-Arm after 90 min of recovery, as was PGC-1α4 mRNA after both 90 and 180 min. Levels of MuRF-1 mRNA was unchanged in R-Arm, but elevated during recovery in ER-Arm, whereas MAFbx mRNA levels increased slightly in both trials. RNA sequencing in a subgroup of subjects revealed 862 differently expressed genes with ER-Arm versus R-Arm during recovery. These findings suggest that leg cycling prior to arm resistance exercise causes systemic changes that potentiate induction of specific genes in the triceps, without compromising the anabolic response.
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Enhanced Skeletal Muscle Oxidative Capacity and Capillary-to-Fiber Ratio Following Moderately Increased Testosterone Exposure in Young Healthy Women.
Cardinale, DA, Horwath, O, Elings-Knutsson, J, Helge, T, Godhe, M, Bermon, S, Moberg, M, Flockhart, M, Larsen, FJ, Hirschberg, AL, et al
Frontiers in physiology. 2020;:585490
Abstract
Background: Recently, it was shown that exogenously administered testosterone enhances endurance capacity in women. In this study, our understanding on the effects of exogenous testosterone on key determinants of oxygen transport and utilization in skeletal muscle is expanded. Methods: In a double-blinded, randomized, placebo-controlled trial, 48 healthy active women were randomized to 10 weeks of daily application of 10 mg of testosterone cream or placebo. Before and after the intervention, VO2 max, body composition, total hemoglobin (Hb) mass and blood volumes were assessed. Biopsies from the vastus lateralis muscle were obtained before and after the intervention to assess mitochondrial protein abundance, capillary density, capillary-to-fiber (C/F) ratio, and skeletal muscle oxidative capacity. Results: Maximal oxygen consumption per muscle mass, Hb mass, blood, plasma and red blood cell volumes, capillary density, and the abundance of mitochondrial protein levels (i.e., citrate synthase, complexes I, II, III, IV-subunit 2, IV-subunit 4, and V) were unchanged by the intervention. However, the C/F ratio, specific mitochondrial respiratory flux activating complex I and linked complex I and II, uncoupled respiration and electron transport system capacity, but not leak respiration or fat respiration, were significantly increased following testosterone administration compared to placebo. Conclusion: This study provides novel insights into physiological actions of increased testosterone exposure on key determinants of oxygen diffusion and utilization in skeletal muscle of women. Our findings show that higher skeletal muscle oxidative capacity coupled to higher C/F ratio could be major contributing factors that improve endurance performance following moderately increased testosterone exposure.
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Proactive Prophylaxis With Azithromycin and HydroxyChloroquine in Hospitalised Patients With COVID-19 (ProPAC-COVID): A structured summary of a study protocol for a randomised controlled trial.
Sivapalan, P, Ulrik, CS, Bojesen, RD, Lapperre, TS, Eklöf, JV, Håkansson, KEJ, Browatzki, A, Tidemansen, C, Wilcke, JT, Janner, J, et al
Trials. 2020;(1):513
Abstract
OBJECTIVES The aim of this randomised GCP-controlled trial is to clarify whether combination therapy with the antibiotic azithromycin and hydroxychloroquine via anti-inflammation/immune modulation, antiviral efficacy and pre-emptive treatment of supra-infections can shorten hospitalisation duration for patients with COVID-19 (measured as "days alive and out of hospital" as the primary outcome), reduce the risk of non- invasive ventilation, treatment in the intensive care unit and death. TRIAL DESIGN This is a multi-centre, randomised, Placebo-controlled, 2-arm ratio 1:1, parallel group double-blind study. PARTICIPANTS 226 participants are recruited at the trial sites/hospitals, where the study will take place in Denmark: Aalborg, Bispebjerg, Gentofte, Herlev, Hillerød, Hvidovre, Odense and Slagelse hospitals. INCLUSION CRITERIA • Patient admitted to Danish emergency departments, respiratory medicine departments or internal medicine departments • Age≥ 18 years • Hospitalized ≤48 hours • Positive COVID-19 test / diagnosis during the hospitalization (confirmed). • Men or non-fertile women. Fertile women* must not be pregnant, i.e. negative pregnancy test must be available at inclusion • Informed consent signed by the patient *Defined as after menarche and until postmenopausal (no menstruation for 12 months) Exclusion criteria: • At the time of recruitment, the patient uses >5 LO2/min (equivalent to 40% FiO2 if measured) • Known intolerance/allergy to azithromycin or hydroxychloroquine or hypersensitivity to quinine or 4-aminoquinoline derivatives • Neurogenic hearing loss • Psoriasis • Retinopathy • Maculopathy • Visual field changes • Breastfeeding • Severe liver diseases other than amoebiasis (INR> 1.5 spontaneously) • Severe gastrointestinal, neurological and hematological disorders (investigator-assessed) • eGFR <45 ml/min/1.73 m2 • Clinically significant cardiac conduction disorders/arrhythmias or prolonged QTc interval (QTc (f) of> 480/470 ms). • Myasthenia gravis • Treatment with digoxin* • Glucose-6-phosphate dehydrogenase deficiency • Porphyria • Hypoglycaemia (Blood glucose at any time since hospitalization of <3.0 mmol/L) • Severe mental illness which significantly impedes cooperation • Severe linguistic problems that significantly hinder cooperation • Treatment with ergot alkaloids *The patient must not be treated with digoxin for the duration of the intervention. For atrial fibrillation/flutter, select according to the Cardiovascular National Treatment Guide (NBV): Calcium antagonist, Beta blocker, direct current (DC) conversion or amiodarone. In case of urgent need for digoxin treatment (contraindication for the aforementioned equal alternatives), the test drug should be paused, and ECG should be taken daily. INTERVENTION AND COMPARATOR Control group: The control group will receive the standard treatment + placebo for both types of intervention medication at all times. If part or all the intervention therapy being investigated becomes standard treatment during the study, this may also be offered to the control group. Intervention group: The patients in the intervention group will also receive standard care. Immediately after randomisation to the intervention group, the patient will begin treatment with: Azithromycin: Day 1-3: 500 mg x 1 Day 4-15: 250 mg x 1 If the patient is unable to take the medication orally by themselves, the medication will, if possible, be administered by either stomach-feeding tube, or alternatively, temporary be changed to clarithromycin 500 mg x 2 (this only in agreement with either study coordinator Pradeesh Sivapalan or principal investigator Jens-Ulrik Stæhr Jensen). This will also be done in the control group if necessary. The patient will switch back to azithromycin when possible. Hydroxychloroquine: Furthermore, the patient will be treated with hydroxychloroquine as follows: Day 1-15: 200 mg x 2 MAIN OUTCOMES • Number of days alive and discharged from hospital within 14 days (summarises both whether the patient is alive and discharged from hospital) ("Days alive and out of hospital") RANDOMISATION The sponsor (Chronic Obstructive Pulmonary Disease Trial Network, COP:TRIN) generates a randomisation sequence. Randomisation will be in blocks of unknown size and the final allocation will be via an encrypted website (REDCap). There will be stratification for age (>70 years vs. <=70 years), site of recruitment and whether the patient has any of the following chronic lung diseases: COPD, asthma, bronchiectasis, interstitial lung disease (Yes vs. No). BLINDING (MASKING): Participants and study personnel will both be blinded, i.e. neither will know which group the participant is allocated to. NUMBERS TO BE RANDOMISED (SAMPLE SIZE): This study requires 226 patients randomised 1:1 with 113 in each group. TRIAL STATUS Protocol version 1.8, from April 16, 2020. Recruitment is ongoing (first patient recruited April 6, 2020; final patient expected to be recruited October 31, 2020). TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT04322396 (registered March 26, 2020) FULL PROTOCOL The full protocol is attached as an additional file, accessible from the Trials website (Additional file 1). In the interest in expediting dissemination of this material, the familiar formatting has been eliminated; this Letter serves as a summary of the key elements of the full protocol. The study protocol has been reported in accordance with the Standard Protocol Items: Recommendations for Clinical Interventional Trials (SPIRIT) guidelines (Additional file 2).
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An exploration of the methods to determine the protein-specific synthesis and breakdown rates in vivo in humans.
Holm, L, Dideriksen, K, Nielsen, RH, Doessing, S, Bechshoeft, RL, Højfeldt, G, Moberg, M, Blomstrand, E, Reitelseder, S, van Hall, G
Physiological reports. 2019;(17):e14143
Abstract
The present study explores the methods to determine human in vivo protein-specific myofibrillar and collagenous connective tissue protein fractional synthesis and breakdown rates. We found that in human myofibrillar proteins, the protein-bound tracer disappearance method to determine the protein fractional breakdown rate (FBR) (via 2 H2 O ingestion, endogenous labeling of 2 H-alanine that is incorporated into proteins, and FBR quantified by its disappearance from these proteins) has a comparable intrasubject reproducibility (range: 0.09-53.5%) as the established direct-essential amino acid, here L-ring-13 C6 -phenylalanine, incorporation method to determine the muscle protein fractional synthesis rate (FSR) (range: 2.8-56.2%). Further, the determination of the protein breakdown in a protein structure with complex post-translational processing and maturation, exemplified by human tendon tissue, was not achieved in this experimentation, but more investigation is encouraged to reveal the possibility. Finally, we found that muscle protein FBR measured with an essential amino acid tracer prelabeling is inappropriate presumably because of significant and prolonged intracellular recycling, which also may become a significant limitation for determination of the myofibrillar FSR when repeated infusion trials are completed in the same participants.
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Activation of mTORC1 by leucine is potentiated by branched-chain amino acids and even more so by essential amino acids following resistance exercise.
Moberg, M, Apró, W, Ekblom, B, van Hall, G, Holmberg, HC, Blomstrand, E
American journal of physiology. Cell physiology. 2016;(11):C874-84
Abstract
Protein synthesis is stimulated by resistance exercise and intake of amino acids, in particular leucine. Moreover, activation of mammalian target of rapamycin complex 1 (mTORC1) signaling by leucine is potentiated by the presence of other essential amino acids (EAA). However, the contribution of the branched-chain amino acids (BCAA) to this effect is yet unknown. Here we compare the stimulatory role of leucine, BCAA, and EAA ingestion on anabolic signaling following exercise. Accordingly, eight trained volunteers completed four sessions of resistance exercise during which they ingested either placebo, leucine, BCAA, or EAA (including the BCAA) in random order. Muscle biopsies were taken at rest, immediately after exercise, and following 90 and 180 min of recovery. Following 90 min of recovery the activity of S6 kinase 1 (S6K1) was greater than at rest in all four trials (Placebo
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Leucine does not affect mechanistic target of rapamycin complex 1 assembly but is required for maximal ribosomal protein s6 kinase 1 activity in human skeletal muscle following resistance exercise.
Apró, W, Moberg, M, Hamilton, DL, Ekblom, B, Rooyackers, O, Holmberg, HC, Blomstrand, E
FASEB journal : official publication of the Federation of American Societies for Experimental Biology. 2015;(10):4358-73
Abstract
We examined how the stimulatory effect of leucine on the mechanistic target of rapamycin complex 1 (mTORC1) pathway is affected by the presence of the remaining essential amino acids (EAAs). Nine male subjects performed resistance exercise on 4 occasions and were randomly supplied EAAs with leucine, EAAs without leucine (EAA-Leu), leucine alone, or flavored water (placebo; control). Muscle biopsies were taken from the vastus lateralis before and 60 and 90 min after exercise. Biopsies were analyzed for protein phosphorylation, kinase activity, protein-protein interactions, amino acid concentrations, and tracer incorporation. Leucine alone stimulated ribosomal protein s6 kinase 1 (S6K1) phosphorylation ∼280% more than placebo and EAA-Leu after exercise. Moreover, this response was enhanced by 60-75% after intake of EAAs compared with that of leucine alone (P < 0.05). Kinase activity of S6K1 reflected that of S6K1 phosphorylation; 60 min after exercise, the activity was elevated 3.3- and 4.2-fold with intake of leucine alone and with EAAs, respectively (P < 0.05). The interaction between mammalian target of rapamycin and regulatory-associated protein of mammalian target of rapamycin was unaltered in response to both resistance exercise and amino acid provision. Leucine alone stimulates mTORC1 signaling, although this response is enhanced by other EAAs and does not appear to be caused by alterations in mTORC1 assembly.
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Absence of leucine in an essential amino acid supplement reduces activation of mTORC1 signalling following resistance exercise in young females.
Moberg, M, Apró, W, Ohlsson, I, Pontén, M, Villanueva, A, Ekblom, B, Blomstrand, E
Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme. 2014;(2):183-94
Abstract
The purpose of the study was to investigate the specific effect of leucine on mTORC1 signalling and amino acid metabolism in connection with resistance exercise. Comparisons were made between ingestion of supplements with and without leucine. Eight young women performed leg press exercise on 2 occasions. In randomized order they received either an aqueous solution of essential amino acids with leucine (EAA) or without leucine (EAA-Leu), given as small boluses throughout the experiment. Muscle biopsies were taken after an overnight fast before exercise and 1 and 3 h postexercise and samples of blood were taken repeatedly during the experiment. Plasma and muscle concentrations of leucine rose 60%-140% (p < 0.05) with EAA and fell 35%-45% (p < 0.05) with the EAA-Leu supplement. In the EAA-trial, plasma and muscle levels of tyrosine (not present in the supplement) and the sum of the EAA were 15%-25% (p < 0.05) lower during recovery. Phosphorylation of mTOR and p70S6k was elevated to a larger extent following 1 h of recovery with leucine in the supplement (120% vs. 49% (p < 0.05) and 59- vs. 8-fold (p < 0.05) for EAA and EAA-Leu, respectively). The levels of MAFbx and MuRF-1 mRNA and of the corresponding proteins were not significantly altered after 3 h recovery from exercise. In conclusion, the presence of leucine in the supplement enhances the stimulatory effect on mTORC1 signalling and reduces the level of tyrosine and the sum of the EAA in muscle and plasma, suggesting a stimulation of protein synthesis and (or) inhibition of breakdown, leading to improvement in net protein balance.