RESUMO
The purpose of this study is to investigate exosome-like vesicle (ELV) plasma concentrations and markers of multivesicular body (MVB) biogenesis in skeletal muscle in response to acute exercise. Seventeen healthy [body mass index (BMI): 23.5 ± 0.5 kg·m-2] and 15 prediabetic (BMI: 27.3 ± 1.2 kg·m-2) men were randomly assigned to two groups performing an acute cycling bout in normoxia or hypoxia ([Formula: see text] 14.0%). Venous blood samples were taken before (T0), during (T30), and after (T60) exercise, and biopsies from m. vastus lateralis were collected before and after exercise. Plasma ELVs were isolated by size exclusion chromatography, counted by nanoparticle tracking analysis (NTA), and characterized according to international standards, followed by expression analyses of canonical ELV markers in skeletal muscle. In the healthy normoxic group, the total number of particles in the plasma increased during exercise from T0 to T30 (+313%) followed by a decrease from T30 to T60 (-53%). In the same group, an increase in TSG101, CD81, and HSP60 protein expression was measured after exercise in plasma ELVs; however, in the prediabetic group, the total number of particles in the plasma was not affected by exercise. The mRNA content of TSG101, ALIX, and CD9 was upregulated in skeletal muscle after exercise in normoxia, whereas CD9 and CD81 were downregulated in hypoxia. ELV plasma abundance increased in response to acute aerobic exercise in healthy subjects in normoxia, but not in prediabetic subjects, nor in hypoxia. Skeletal muscle analyses suggested that this tissue did not likely play a major role of the exercise-induced increase in circulating ELVs.
Assuntos
Exercício Físico , Vesículas Extracelulares/metabolismo , Hipóxia/sangue , Corpos Multivesiculares/metabolismo , Contração Muscular , Estado Pré-Diabético/sangue , Músculo Quadríceps/metabolismo , Adulto , Ciclismo , Proteínas de Ligação ao Cálcio/sangue , Estudos de Casos e Controles , Proteínas de Ciclo Celular/sangue , Proteínas de Ligação a DNA/sangue , Complexos Endossomais de Distribuição Requeridos para Transporte/sangue , Humanos , Hipóxia/diagnóstico , Hipóxia/fisiopatologia , Masculino , Pessoa de Meia-Idade , Biogênese de Organelas , Estado Pré-Diabético/diagnóstico , Estado Pré-Diabético/fisiopatologia , Músculo Quadríceps/fisiopatologia , Distribuição Aleatória , Tetraspanina 29/sangue , Fatores de Tempo , Fatores de Transcrição/sangueRESUMO
This study aimed to investigate the mechanisms known to regulate glucose homeostasis in human skeletal muscle of healthy and prediabetic subjects exercising in normobaric hypoxia. Seventeen healthy (H; 28.8 ± 2.4 yr; maximal oxygen consumption (VÌO2max): 45.1 ± 1.8 mL·kg-1·min-1) and 15 prediabetic (P; 44.6 ± 3.9 yr; VÌO2max: 30.8 ± 2.5 mL·kg-1·min-1) men were randomly assigned to two groups performing an acute exercise bout (heart rate corresponding to 55% VÌO2max) either in normoxic (NE) or in hypoxic (HE; fraction of inspired oxygen [Formula: see text] 14.0%) conditions. An oral glucose tolerance test (OGTT) was performed in a basal state and after an acute exercise bout. Muscle biopsies from m. vastus lateralis were taken before and after exercise. Venous blood samples were taken at regular intervals before, during, and after exercise. The two groups exercising in hypoxia had a larger area under the curve of blood glucose levels during the OGTT after exercise compared with baseline (H: +11%; P: +4%). Compared with pre-exercise, an increase in p-TBC1D1 Ser237 and in p-AMPK Thr172 was observed postexercise in P NE (+95%; +55%, respectively) and H HE (+91%; +43%, respectively). An increase in p-ACC Ser212 was measured after exercise in all groups (H NE: +228%; P NE: +252%; H HE: +252%; P HE: +208%). Our results show that an acute bout of exercise in hypoxia reduces glucose tolerance in healthy and prediabetic subjects. At a molecular level, some adaptations regulating glucose transport in muscle were found in all groups without associations with glucose tolerance after exercise. The results suggest that hypoxia negatively affects glucose tolerance postexercise through unidentified mechanisms.NEW & NOTEWORTHY The molecular mechanisms involved in glucose tolerance after acute exercise in hypoxia have not yet been elucidated in human. Due to the reversible character of their status, prediabetic individuals are of particular interest for preventing the development of type 2 diabetes. The present study is the first to investigate muscle molecular mechanisms during exercise and glucose metabolism after exercise in prediabetic and healthy subjects exercising in normoxia and normobaric hypoxia.
Assuntos
Exercício Físico/fisiologia , Teste de Tolerância a Glucose , Hipóxia/metabolismo , Estado Pré-Diabético/metabolismo , Adulto , Limiar Anaeróbio , Glicemia/análise , Glicemia/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Transportador de Glucose Tipo 4/metabolismo , Glicogênio/metabolismo , Humanos , Insulina/sangue , Insulina/farmacologia , Lipídeos/sangue , Masculino , Músculo Esquelético/metabolismoRESUMO
Acute environmental hypoxia may potentiate muscle hypertrophy in response to resistance training but the mechanisms are still unknown. To this end, twenty subjects performed a 1-leg knee extension session (8 sets of 8 repetitions at 80% 1 repetition maximum, 2-min rest between sets) in normoxic or normobaric hypoxic conditions (FiO2 14%). Muscle biopsies were taken 15 min and 4 hours after exercise in the vastus lateralis of the exercised and the non-exercised legs. Blood samples were taken immediately, 2h and 4h after exercise. In vivo, hypoxic exercise fostered acute inflammation mediated by the TNFα/NF-κB/IL-6/STAT3 (+333%, +194%, + 163% and +50% respectively) pathway, which has been shown to contribute to satellite cells myogenesis. Inflammation activation was followed by skeletal muscle invasion by CD68 (+63%) and CD197 (+152%) positive immune cells, both known to regulate muscle regeneration. The role of hypoxia-induced activation of inflammation in myogenesis was confirmed in vitro. Acute hypoxia promoted myogenesis through increased Myf5 (+300%), MyoD (+88%), myogenin (+1816%) and MRF4 (+489%) mRNA levels in primary myotubes and this response was blunted by siRNA targeting STAT3. In conclusion, our results suggest that hypoxia could improve muscle hypertrophic response following resistance exercise through IL-6/STAT3-dependent myogenesis and immune cells-dependent muscle regeneration.
Assuntos
Exercício Físico/fisiologia , Hipóxia/patologia , Inflamação/patologia , Desenvolvimento Muscular/fisiologia , Células Satélites de Músculo Esquelético/patologia , Transdução de Sinais/fisiologia , Células Cultivadas , Humanos , Hipóxia/metabolismo , Inflamação/metabolismo , Fibras Musculares Esqueléticas/metabolismo , Fibras Musculares Esqueléticas/patologia , Proteínas Musculares/metabolismo , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , RNA Mensageiro/metabolismo , Treinamento Resistido/métodos , Células Satélites de Músculo Esquelético/metabolismoRESUMO
The aim of the present study was to determine if the training status decreases inflammation, slows down senescence, and preserves telomere health in skeletal muscle in older compared with younger subjects, with a specific focus on satellite cells. Analyses were conducted on skeletal muscle and cultured satellite cells from vastus lateralis biopsies (n = 34) of male volunteers divided into four groups: young sedentary (YS), young trained cyclists (YT), old sedentary (OS), and old trained cyclists (OT). The senescence state and inflammatory profile were evaluated by telomere dysfunction-induced foci (TIF) quantification, senescence-associated ß-galactosidase (SA-ß-Gal) staining, and quantitative (q)RT-PCR. Independently of the endurance training status, TIF levels (+35%, P < 0.001) and the percentage of SA-ß-Gal-positive cells (+30%, P < 0.05) were higher in cultured satellite cells of older compared with younger subjects. p16 (4- to 5-fold) and p21 (2-fold) mRNA levels in skeletal muscle were higher with age but unchanged by the training status. Aging induced higher CD68 mRNA levels in human skeletal muscle (+102%, P = 0.009). Independently of age, both trained groups had lower IL-8 mRNA levels (-70%, P = 0.011) and tended to have lower TNF-α mRNA levels (-40%, P = 0.10) compared with the sedentary subjects. All together, we found that the endurance training status did not slow down senescence in skeletal muscle and satellite cells in older compared with younger subjects despite reduced inflammation in skeletal muscle. These findings highlight that the link between senescence and inflammation can be disrupted in skeletal muscle.
Assuntos
Envelhecimento/fisiologia , Treino Aeróbico , Inflamação/prevenção & controle , Músculo Esquelético/fisiologia , Resistência Física/fisiologia , Homeostase do Telômero/fisiologia , Idoso , Senescência Celular/genética , Senescência Celular/fisiologia , Inibidor p16 de Quinase Dependente de Ciclina/genética , Inibidor de Quinase Dependente de Ciclina p21/genética , Humanos , Masculino , Músculo Esquelético/química , Músculo Esquelético/citologia , RNA Mensageiro/análise , Células Satélites de Músculo Esquelético/fisiologia , Células Satélites de Músculo Esquelético/ultraestrutura , Telômero/fisiologia , Telômero/ultraestrutura , Adulto Jovem , beta-Galactosidase/análiseRESUMO
PURPOSE: This study aimed to investigate the modulation of circulating exosome-like extracellular vesicles (ELVs) after 6 wk of sprint interval training (SIT) at sea level and at 2000, 3000, and 4000 m. METHODS: Thirty trained endurance male athletes (18-35 yr) participated in a 6-wk SIT program (30-s all-out sprint, 4-min 30-s recovery; 4-9 repetitions, 2 sessions per week) at sea level ( n = 8), 2000 m (fraction of inspired oxygen (F io2 ) 0.167, n = 8), 3000 m (F io2 0.145, n = 7), or 4000 m (F io2 0.13, n = 7). Venous blood samples were taken before and after the training period. Plasma ELVs were isolated by size exclusion chromatography, counted by nanoparticle tracking analysis, and characterized according to international standards. Candidate ELV microRNAs (miRNAs) were quantified by real-time polymerase chain reaction. RESULTS: When the three hypoxic groups were analyzed separately, only very minor differences could be detected in the levels of circulating particles, ELV markers, or miRNA. However, the levels of circulating particles increased (+262%) after training when the three hypoxic groups were pooled, and tended to increase at sea level (+65%), with no difference between these two groups. A trend to an increase was observed for the two ELV markers, TSG101 (+65%) and HSP60 (+441%), at sea level, but not in hypoxia. Training also seemed to decrease the abundance of miR-23a-3p and to increase the abundance of miR-21-5p in hypoxia but not at sea level. CONCLUSIONS: A 6-wk SIT program tended to increase the basal levels of circulating ELVs when performed at sea level but not in hypoxia. In contrast, ELV miRNA cargo seemed to be modulated in hypoxic conditions only. Further research should explore the potential differences in the origin of ELVs between normoxic and local and systemic hypoxic conditions.
Assuntos
Vesículas Extracelulares , Treinamento Intervalado de Alta Intensidade , MicroRNAs , Humanos , Masculino , Altitude , Exossomos , Hipóxia , Adolescente , Adulto Jovem , AdultoRESUMO
Impaired metabolism is becoming one of the main causes of mortality and the identification of strategies to cure those diseases is a major public health concern. A number of therapies are being developed to treat type 2 diabetes mellitus (T2DM), but few of them focus on situations prior to diabetes. Obesity, aging and insulin resistance are all risk factors, which fortunately can be reversed to some extent. Non-drug interventions, such as exercise, are interesting strategies to prevent the onset of diabetes, but it remains to determine the optimal dose and conditions. In the search of optimizing the effects of physical exercise to prevent T2DM, hypoxic training has emerged as an interesting and original strategy. Several recent studies have chosen to look at the effects of hypoxic training in people at risk of developing T2DM. Therefore, the purpose of this narrative review is to give an overview of all original articles having tested the effects of a single exercise or exercise training in hypoxia on glucose metabolism and other health-related parameters in people at risk of developing T2DM. Taken together, the data on the effects of hypoxic training on glucose metabolism, insulin sensitivity and the health status of people at risk of T2DM are inconclusive. Some studies show that hypoxic training can improve glucose metabolism and the health status to a greater extent than normoxic training, while others do not corroborate the latter. When an additional benefit of hypoxic vs normoxic training is found, it still remains to determine which signaling pathways and molecular mechanisms are involved.
RESUMO
BACKGROUND: A light but regular combined training program is sufficient to improve health in obese adolescents. Hypoxia is known to potentiate the effects of a high intensity period of combined training on exercise performance and glucose metabolism in this population. Here, we tested the effects of a less intensive hypoxic combined training program on exercise performance and health-related markers in obese adolescents. METHODS: Fourteen adolescents volunteered to participate to a 30-week combined training protocol whether in normoxia (FiO2 21%, NE, N.=7) or in hypoxia (FiO2 15%, HE, N.=7). Once a week, adolescents exercised for 50-60min including 12min on a cycloergometer and strength training of the abdominal, quadriceps and biceps muscles. RESULTS: Combined training reduced body mass (NE: -12%; HE: -8%), mainly due to a loss in fat mass (NE: -26%; HE: -15%), similarly in both the hypoxic and normoxic groups. After training, maximal O2 consumption (VO2max) (NE: +30%; HE: +25%,), maximal aerobic power (MAP) (NE: +20%; HE: +36%), work capacity and one-repetition maximum (1RM) for the quadriceps (NE: +26%; HE: +12%), abdominal (NE: +48%; HE: +36%) and biceps muscles (NE: +26%; HE: +16%) were increased similarly in both groups but insulin sensitivity markers were not modified. CONCLUSIONS: Except for insulin sensitivity, 1h a week of combined training for 30 weeks improved morphological and health-related markers as well as exercise performance in obese adolescents in both normoxic and hypoxic conditions. This is of particular importance for motivating those adolescents, who often are reluctant to exercise. Even a low dose of exercise per week can induce positive health outcomes.
Assuntos
Terapia por Exercício , Hipóxia/terapia , Obesidade/terapia , Adolescente , Criança , Exercício Físico/fisiologia , Feminino , Humanos , Hipóxia/metabolismo , Insulina/metabolismo , Resistência à Insulina , Masculino , Músculo Esquelético/metabolismo , Obesidade/metabolismo , Oxigênio/metabolismo , Consumo de Oxigênio , Projetos Piloto , Treinamento Resistido , Testes de Função RespiratóriaRESUMO
BACKGROUND: Skeletal muscle wasting is often associated with insulin resistance. A major regulator of muscle mass is the transforming growth factor ß (TGF-ß) superfamily, including activin A, which causes atrophy. TGF-ß superfamily ligands also negatively regulate insulin-sensitive proteins, but whether this pathway contributes to insulin action remains to be determined. METHODS: To elucidate if TGF-ß superfamily ligands regulate insulin action, we used an adeno-associated virus gene editing approach to overexpress an activin A inhibitor, follistatin (Fst288), in mouse muscle of lean and diet-induced obese mice. We determined basal and insulin-stimulated 2-deoxy-glucose uptake using isotopic tracers in vivo. Furthermore, to evaluate whether circulating Fst and activin A concentrations are associated with obesity, insulin resistance, and weight loss in humans, we analysed serum from morbidly obese subjects before, 1 week, and 1 year after Roux-en-Y gastric bypass (RYGB). RESULTS: Fst288 muscle overexpression markedly increased in vivo insulin-stimulated (but not basal) glucose uptake (+75%, P < 0.05) and increased protein expression and intracellular insulin signalling of AKT, TBC1D4, PAK1, pyruvate dehydrogenase-E1α, and p70S6K, while decreasing TBC1D1 signaling (P < 0.05). Fst288 increased both basal and insulin-stimulated protein synthesis, but no correlation was observed between the Fst288-driven hypertrophy and the increase in insulin-stimulated glucose uptake. Importantly, Fst288 completely normalized muscle glucose uptake in insulin-resistant diet-induced obese mice. RYGB surgery doubled circulating Fst and reduced activin A (-24%, P < 0.05) concentration 1 week after surgery before any significant weight loss in morbidly obese normoglycemic patients, while major weight loss after 1 year did not further change the concentrations. CONCLUSIONS: We here present evidence that Fst is a potent regulator of insulin action in muscle, and in addition to AKT and p70S6K, we identify TBC1D1, TBC1D4, pyruvate dehydrogenase-E1α, and PAK1 as Fst targets. Circulating Fst more than doubled post-RYGB surgery, a treatment that markedly improved insulin sensitivity, suggesting a role for Fst in regulating glycaemic control. These findings demonstrate the therapeutic potential of inhibiting TGF-ß superfamily ligands to improve insulin action and Fst's relevance to muscle wasting-associated insulin-resistant conditions in mice and humans.
Assuntos
Folistatina/sangue , Folistatina/genética , Atrofia Muscular/metabolismo , Obesidade/cirurgia , Adulto , Animais , Dependovirus , Feminino , Derivação Gástrica , Vetores Genéticos/farmacologia , Células HEK293 , Humanos , Subunidades beta de Inibinas/antagonistas & inibidores , Subunidades beta de Inibinas/sangue , Resistência à Insulina , Masculino , Camundongos , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , Atrofia Muscular/genética , Atrofia Muscular/patologia , Obesidade/sangue , Parvovirinae/genética , Ratos , Transdução de SinaisRESUMO
PURPOSE: This study aimed to test whether environmental hypoxia could potentiate the effects of exercise training on glucose metabolism and insulin sensitivity. METHODS: Fourteen adolescents with obesity were assigned to 6 wk of exercise training either in normoxic or in hypoxic conditions (FiO2 15%). Adolescents trained three times per week for 50-60 min, including endurance and resistance exercises. Oral glucose tolerance test, blood and morphological analyses, and physical performance tests were performed before and after the training period. RESULTS: After training, hypoxia, but not normoxia, decreased the area under the curve of plasma insulin (-49%; P = 0.001) and glucose levels (-14%; P = 0.005) during oral glucose tolerance test. Decreased plasma triglycerides levels (P = 0.03) and increased maximal aerobic power (P = 0.002), work capacity at 160 bpm (P = 0.002), and carbohydrate consumption during exercise (P = 0.03) were measured only in the hypoxic group. CONCLUSIONS: Hypoxic exercise training was particularly efficient at improving glucose tolerance and insulin response to a glucose challenge in adolescents with obesity. These results suggest that exercise training in hypoxia could be an interesting strategy against insulin resistance and type 2 diabetes development in adolescents with obesity.
Assuntos
Glicemia/metabolismo , Treino Aeróbico/métodos , Teste de Tolerância a Glucose , Resistência à Insulina , Insulina/sangue , Obesidade Infantil/sangue , Obesidade Infantil/terapia , Treinamento Resistido/métodos , Adolescente , Proteína C-Reativa/metabolismo , Colesterol/sangue , Diabetes Mellitus Tipo 2/prevenção & controle , Metabolismo Energético , Humanos , Hipóxia , Músculo Esquelético/metabolismo , Obesidade Infantil/fisiopatologia , Método Simples-Cego , Triglicerídeos/sangueRESUMO
Exercise bypasses insulin resistance to increase glucose uptake in skeletal muscle and therefore represents an important alternative to stimulate glucose uptake in insulin-resistant muscle. Both Rac1 and AMPK have been shown to partly regulate contraction-stimulated muscle glucose uptake, but whether those two signaling pathways jointly account for the entire signal to glucose transport is unknown. We therefore studied the ability of contraction and exercise to stimulate glucose transport in isolated muscles with AMPK loss of function combined with either pharmacological inhibition or genetic deletion of Rac1.Muscle-specific knockout (mKO) of Rac1, a kinase-dead α2 AMPK (α2KD), and double knockout (KO) of ß1 and ß2 AMPK subunits (ß1ß2 KO) each partially decreased contraction-stimulated glucose transport in mouse soleus and extensor digitorum longus (EDL) muscle. Interestingly, when pharmacological Rac1 inhibition was combined with either AMPK ß1ß2 KO or α2KD, contraction-stimulated glucose transport was almost completely inhibited. Importantly, α2KD+Rac1 mKO double-transgenic mice also displayed severely impaired contraction-stimulated glucose transport, whereas exercise-stimulated glucose uptake in vivo was only partially reduced by Rac1 mKO with no additive effect of α2KD. It is concluded that Rac1 and AMPK together account for almost the entire ex vivo contraction response in muscle glucose transport, whereas only Rac1, but not α2 AMPK, regulates muscle glucose uptake during submaximal exercise in vivo.