RESUMO
This study aimed to evaluate the influence of combined intermittent fasting (IF) and high-intensity interval training (HIIT) on morphology, caspase-independent apoptosis signaling pathway, and myostatin expression in soleus and gastrocnemius (white portion) muscles from healthy rats. Sixty-day-old male Wistar rats (n = 60) were divided into four groups: control (C), IF, high-intensity-interval training (T), and high-intensity-interval training and intermittent fasting (T-IF). The C and T groups received ad libitum chow daily; IF and T-IF received the same standard chow every other day. Animals from T and T-IF underwent a HIIT protocol five times a week for 12 weeks. IF reduced gastrocnemius mass and increased pro-apoptotic proteins apoptosis-inducing factor (AIF) and endonuclease G (EndoG) in soleus and cleaved-to-non-cleaved PARP-1 ratio and myostatin expression in gastrocnemius white portion. HIIT increased AIF and apoptosis repressor with caspase recruitment domain expression in soleus and cleaved-to-total PARP-1 ratio in gastrocnemius muscle white portion. The combination of IF and HIIT reduced fiber cross-sectional area in both muscles, increased EndoG and AIF expression, and decreased cleaved-to-non-cleaved PARP-1 ratio in gastrocnemius muscle white portion. Muscle responses to IF and HIIT are directly impacted by the muscle fiber type composition and are modulated, at least in part, by myostatin and caspase-independent apoptosis signaling.
Assuntos
Fator de Indução de Apoptose , Apoptose , Jejum , Treinamento Intervalado de Alta Intensidade , Fibras Musculares de Contração Lenta , Atrofia Muscular , Miostatina , Ratos Wistar , Transdução de Sinais , Animais , Masculino , Apoptose/fisiologia , Jejum/metabolismo , Jejum/fisiologia , Miostatina/metabolismo , Treinamento Intervalado de Alta Intensidade/métodos , Ratos , Transdução de Sinais/fisiologia , Atrofia Muscular/metabolismo , Atrofia Muscular/patologia , Fator de Indução de Apoptose/metabolismo , Fibras Musculares de Contração Lenta/metabolismo , Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Rápida/patologia , Endodesoxirribonucleases/metabolismo , Condicionamento Físico Animal/métodos , Condicionamento Físico Animal/fisiologia , Músculo Esquelético/metabolismo , Jejum Intermitente , Poli(ADP-Ribose) Polimerase-1RESUMO
BACKGROUND: Betaglycan, also known as the TGFß type III receptor (Tgfbr3), is a co-receptor that modulates TGFß family signaling. Tgfbr3 is upregulated during C2C12 myoblast differentiation and expressed in mouse embryos myocytes. RESULTS: To investigate tgfbr3 transcriptional regulation during zebrafish embryonic myogenesis, we cloned a 3.2 kb promoter fragment that drives reporter transcription during C2C12 myoblasts differentiation and in the Tg(tgfbr3:mCherry) transgenic zebrafish. We detect tgfbr3 protein and mCherry expression in the adaxial cells concomitantly with the onset of their radial migration to become slow-twitch muscle fibers in the Tg(tgfbr3:mCherry). Remarkably, this expression displays a measurable antero-posterior somitic gradient expression. CONCLUSIONS: tgfbr3 is transcriptionally regulated during somitic muscle development in zebrafish with an antero-posterior gradient expression that preferentially marks the adaxial cells and their descendants.
Assuntos
Somitos , Peixe-Zebra , Animais , Camundongos , Somitos/metabolismo , Proteoglicanas/metabolismo , Fibras Musculares de Contração Lenta/metabolismo , Fator de Crescimento Transformador beta/metabolismo , Desenvolvimento Muscular/fisiologiaRESUMO
The aim of the study was to address the genioglossus muscle physiological and histological changes after unilateral nasal obstruction in growing rats. Fifty-four 6-day-old male Wistar albino rats were randomly divided into control (n = 27) and experimental (n = 27) groups. Unilateral nasal obstruction was performed at 8 days old. Contractile properties of the genioglossus whole muscle were measured at 5-, 7- and 9-week-old, including the twitch and tetanic forces, contraction time, half-decay time, and fatigue index. The histological characteristics of the genioglossus were also evaluated at 5-, 7- and 9-week-old, analyzing the myosin heavy chain composition of the slow, fast, IIa and IIb muscle fiber type, by measuring the number, rate, diameter and cross-sectional area. The maximal twitch force, and tetanic force at 60 Hz and 80 Hz force was significantly increased at all ages after nasal obstruction. The fatigue index was decreased at 5 weeks-old after nasal obstruction. The diameter and cross-sectional area of the fast, IIa and IIb muscle fiber types were increased at 7 and 9 weeks after nasal obstruction, while only the diameter of IIa type and cross-sectional area of IIb type were increased at 5 weeks-old after nasal obstruction. Nasal obstruction during growth affects the whole genioglossus muscle contractile properties and histological characteristics, increasing its force, the diameter and area of its muscle fibers. These changes in the genioglossus muscle may affect the normal growth, development and function of the craniofacial complex.
Assuntos
Obstrução Nasal , Animais , Ratos , Masculino , Ratos Wistar , Contração Muscular/fisiologia , Músculos Faciais , Cadeias Pesadas de Miosina , Fadiga/patologia , Músculo Esquelético/fisiologia , Fibras Musculares de Contração Rápida/fisiologia , Fibras Musculares de Contração LentaRESUMO
Acute respiratory distress syndrome is associated with skeletal muscle compromise, which decreases survival and impairs functional capacity. A comparative analysis of peripheral and respiratory muscles' atrophy and dysfunction in acute lung injury (ALI) has not been performed. We aimed to evaluate diaphragmatic and peripheral muscle mass and contractility in an ALI animal model. ALI was induced in C57BL/6 mice by intratracheal lipopolysaccharides instillation. Muscle mass and in vitro contractility were evaluated at different time points in hindlimb soleus (slow-twitch) and extensor digitorum longus (EDL, fast-twitch), as well as in the main respiratory muscle diaphragm. Myogenic precursor satellite cell-specific transcription factor Pax7 expression was determined by Western blot. Lung injury was associated with atrophy of the three studied muscles, although it was more pronounced and persistent in the diaphragm. Specific contractility was reduced during lung injury in EDL muscle but restored by the time lung injury has resolved. Specific force was not affected in soleus and diaphragm. A persistent increase in Pax7 expression was detected in diaphragm and EDL muscles after induction of ALI, but not in soleus muscle. Different peripheral and respiratory skeletal muscles are distinctly affected during the course of ALI. Each of the studied muscles presented a unique pattern in terms of atrophy development, contractile dysfunction and Pax7 expression.
Assuntos
Lesão Pulmonar Aguda , Doenças Musculares , Lesão Pulmonar Aguda/metabolismo , Animais , Atrofia , Camundongos , Camundongos Endogâmicos C57BL , Contração Muscular , Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Lenta/metabolismo , Músculo Esquelético/fisiologia , Doenças Musculares/metabolismo , Músculos RespiratóriosRESUMO
BACKGROUND: Fetal stage is a critical developmental window for the skeletal muscle, but little information is available about the impact of maternal vitamin D (Vit. D) deficiency (VDD) on offspring lean mass development in the adult life of male and female animals. METHODS: Female rats (Wistar Hannover) were fed either a control (1000 IU Vit. D3/kg) or a VDD diet (0 IU Vit. D3/kg) for 6 weeks and during gestation and lactation. At weaning, male and female offspring were randomly separated and received a standard diet up to 180 days old. RESULTS: Vitamin D deficiency induced muscle atrophy in the male (M-VDD) offspring at the end of weaning, an effect that was reverted along the time. Following 180 days, fast-twitch skeletal muscles [extensor digitorum longus (EDL)] from the M-VDD showed a decrease (20%; P < 0.05) in the number of total fibres but an increase in the cross-sectional area of IIB (17%; P < 0.05), IIA (19%; P < 0.05) and IIAX (21%; P < 0.05) fibres. The fibre hypertrophy was associated with the higher protein levels of MyoD (73%; P < 0.05) and myogenin (55% %; P < 0.05) and in the number of satellite cells (128.8 ± 14 vs. 91 ± 7.6 nuclei Pax7 + in the M-CTRL; P < 0.05). M-VDD increased time to fatigue during ex vivo contractions of EDL muscles and showed an increase in the phosphorylation levels of IGF-1/insulin receptor and their downstream targets related to anabolic processes and myogenic activation, including Ser 473 Akt and Ser 21/9 GSK-3ß. In such muscles, maternal VDD induced a compensatory increase in the content of calcitriol (two-fold; P < 0.05) and CYP27B1 (58%; P < 0.05), a metabolizing enzyme that converts calcidiol to calcitriol. Interestingly, most morphological and biochemical changes found in EDL were not observed in slow-twitch skeletal muscles (soleus) from the M-VDD group as well as in both EDL and soleus muscles from the female offspring. CONCLUSIONS: These data show that maternal VDD selectively affects the development of type-II muscle fibres in male offspring rats but not in female offspring rats and suggest that the enhancement of their size and fatigue resistance in fast-twitch skeletal muscle (EDL) is probably due to a compensatory increase in the muscle content of Vit. D in the adult age.
Assuntos
Fibras Musculares de Contração Lenta , Deficiência de Vitamina D , Animais , Calcitriol/análise , Calcitriol/metabolismo , Calcitriol/farmacologia , Feminino , Glicogênio Sintase Quinase 3 beta/análise , Glicogênio Sintase Quinase 3 beta/metabolismo , Glicogênio Sintase Quinase 3 beta/farmacologia , Masculino , Fibras Musculares de Contração Rápida/fisiologia , Fibras Musculares de Contração Lenta/fisiologia , Músculo Esquelético/metabolismo , Ratos , Ratos Wistar , Deficiência de Vitamina D/complicações , Deficiência de Vitamina D/metabolismoRESUMO
Mag-Fluo-4 has revealed differences in the kinetics of the Ca2+ transients of mammalian fiber types (I, IIA, IIX, and IIB). We simulated the changes in [Ca2+] through the sarcomere of these four fiber types, considering classical (troponin -Tn-, parvalbumin -Pv-, adenosine triphosphate -ATP-, sarcoplasmic reticulum Ca2+ pump -SERCA-, and dye) and new (mitochondria -MITO-, Na+/Ca2+ exchanger -NCX-, and store-operated calcium entry -SOCE-) Ca2+ binding sites, during single and tetanic stimulation. We found that during a single twitch, the sarcoplasmic peak [Ca2+] for fibers type IIB and IIX was around 16 µM, and for fibers type I and IIA reached 10-13 µM. The release rate in fibers type I, IIA, IIX, and IIB was 64.8, 153.6, 238.8, and 244.5 µM ms-1, respectively. Both the pattern of change and the peak concentrations of the Ca2+-bound species in the sarcoplasm (Tn, PV, ATP, and dye), the sarcolemma (NCX, SOCE), and the SR (SERCA) showed the order IIB ≥ IIX > IIA > I. The capacity of the NCX was 2.5, 1.3, 0.9, and 0.8% of the capacity of SERCA, for fibers type I, IIA, IIX, and IIB, respectively. MITO peak [Ca2+] ranged from 0.93 to 0.23 µM, in fibers type I and IIB, respectively, while intermediate values were obtained in fibers IIA and IIX. The latter numbers doubled during tetanic stimulation. In conclusion, we presented a comprehensive mathematical model of the excitation-contraction coupling that integrated most classical and novel Ca2+ handling mechanisms, overcoming the limitations of the fast- vs. slow-fibers dichotomy and the use of slow dyes.
Assuntos
Cálcio/metabolismo , Acoplamento Excitação-Contração/fisiologia , Modelos Teóricos , Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Lenta/metabolismo , Sarcômeros/metabolismo , Trifosfato de Adenosina/metabolismo , Animais , Simulação por Computador , Cinética , Camundongos , Mitocôndrias/metabolismo , Parvalbuminas/metabolismo , Retículo Sarcoplasmático/metabolismo , Troponina/metabolismoRESUMO
We tested the hypothesis that cancer cachexia progression would induce oxidative post-translational modifications (Ox-PTMs) associated with skeletal muscle wasting, with different responses in muscles with the prevalence of glycolytic and oxidative fibers. We used cysteine-specific isotopic coded affinity tags (OxICAT) and gel-free mass spectrometry analysis to investigate the cysteine Ox-PTMs profile in the proteome of both plantaris (glycolytic) and soleus (oxidative) muscles in tumor-bearing and control rats. Histological analysis revealed muscle atrophy in type II fibers in plantaris muscle, with no changes in plantaris type I fibers and no differences in both soleus type I and II fibers in tumor-bearing rats when compared to healthy controls. Tumor progression altered the Ox-PTMs profile in both plantaris and soleus. However, pathway analysis including the differentially oxidized proteins revealed tricarboxylic acid cycle and oxidative phosphorylation as main affected pathways in plantaris muscle from tumor-bearing rats, while the same analysis did not show main metabolic pathways affected in the soleus muscle. In addition, cancer progression affected several metabolic parameters such as ATP levels and markers of oxidative stress associated with muscle atrophy in plantaris muscle, but not in soleus. However, isolated soleus from tumor-bearing rats had a reduced force production capacity when compared to controls. These novel findings demonstrate that tumor-bearing rats have severe muscle atrophy exclusively in glycolytic fibers. Cancer progression is associated with cysteine Ox-PTMs in the skeletal muscle, but these modifications affect different pathways in a glycolytic muscle compared to an oxidative muscle, indicating that intrinsic muscle oxidative capacity determines the response to cancer cachectic effects.
Assuntos
Músculo Esquelético/patologia , Atrofia Muscular/patologia , Neoplasias/patologia , Estresse Oxidativo/fisiologia , Animais , Caquexia/patologia , Progressão da Doença , Glicólise/fisiologia , Masculino , Fibras Musculares de Contração Rápida/patologia , Fibras Musculares de Contração Lenta/patologia , Oxirredução , Fosforilação Oxidativa , Ratos , Ratos WistarRESUMO
BACKGROUND: previous studies have shown that muscle atrophy is observed after sleep deprivation (SD) protocols; however, the mechanisms responsible are not fully understood. Muscle trophism can be modulated by several factors, including energy balance (positive or negative), nutritional status, oxidative stress, the level of physical activity, and disuse. The metabolic differences that exist in different types of muscle fiber may also be the result of different adaptive responses. To better understand these mechanisms, we evaluated markers of oxidative damage and histopathological changes in different types of muscle fibers in sleep-deprived rats. METHODS: Twenty male Wistar EPM-1 rats were randomly allocated in two groups: a control group (CTL group; n = 10) and a sleep deprived group (SD group; n = 10). The SD group was submitted to continuous paradoxical SD for 96 h; the soleus (type I fibers) and plantar (type II fiber) muscles were analyzed for histopathological changes, trophism, lysosomal activity, and oxidative damage. Oxidative damage was assessed by lipid peroxidation and nuclear labeling of 8-OHdG. RESULTS: The data demonstrated that SD increased the nuclear labeling of 8-OHdG and induced histopathological changes in both muscles, being more evident in the soleus muscle. In the type I fibers there was signs of tissue degeneration, inflammatory infiltrate and tissue edema. Muscle atrophy was observed in both muscles. The concentration of malondialdehyde, and cathepsin L activity only increased in type I fibers after SD. CONCLUSION: These data indicate that the histopathological changes observed after 96 h of SD in the skeletal muscle occur by different processes, according to the type of muscle fiber, with muscles predominantly composed of type I fibers undergoing greater oxidative damage and catabolic activity, as evidenced by a larger increase in 8-OHdG labeling, lipid peroxidation, and lysosomal activity.
Assuntos
Fibras Musculares de Contração Rápida , Fibras Musculares de Contração Lenta , Estresse Oxidativo , Privação do Sono , Animais , Masculino , Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Rápida/patologia , Fibras Musculares de Contração Lenta/metabolismo , Fibras Musculares de Contração Lenta/patologia , Atrofia Muscular/metabolismo , Atrofia Muscular/patologia , Ratos , Ratos Wistar , Privação do Sono/metabolismo , Privação do Sono/patologiaRESUMO
Muscle fibres are classified as fast, intermediate and slow. In vitro myoblast cell culture model from fast muscle is a very useful tool to study muscle growth and development; however, similar models for slow muscle do not exist. Owing to the compartmentalization of fish muscle fibres, we have developed a slow myoblast cell culture for rainbow trout (Oncorhynchus mykiss). Slow and fast muscle-derived myoblasts have similar morphology, but with differential expression of slow muscle markers such as slow myhc, sox6 and pgc-1α We also characterized the mir-133 and mir-499 microRNA families in trout slow and fast myoblasts as a case study during myogenesis and in response to electrostimulation. Three mir-133 (a-1a, a-1b and a-2) and four mir-499 (aa, ab, ba and bb) paralogues were identified for rainbow trout and named base on their phylogenetic relationship to zebrafish and Atlantic salmon orthologues. Omy-mir-499ab and omy-mir-499bb had 0.6 and 0.5-fold higher expression in slow myoblasts compared with fast myoblasts, whereas mir-133 duplicates had similar levels in both phenotypes and little variation during development. Slow myoblasts also showed increased expression for omy-mir-499b paralogues in response to chronic electrostimulation (7-fold increase for omy-mir-499ba and 2.5-fold increase for omy-mir-499bb). The higher expression of mir-499 paralogues in slow myoblasts suggests a role in phenotype determination, while the lack of significant differences of mir-133 copies during culture development might indicate a different role in fish compared with mammals. We have also found signs of sub-functionalization of mir-499 paralogues after electrostimulation, with omy-mir-499b copies more responsive to electrical signals.
Assuntos
MicroRNAs/metabolismo , Mioblastos Esqueléticos/fisiologia , Oncorhynchus mykiss , Animais , Técnicas de Cultura de Células/métodos , Desenvolvimento Muscular , Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Lenta/metabolismo , Mioblastos Esqueléticos/metabolismoRESUMO
En los últimos años, la vocología ha prestado un interés particular a la investigación y aplicación clínica de principios basados en la ciencia que permitan maximizar el aprendizaje y el control motor asociados al funcionamiento de la voz. El proceso de producción vocal ocurre gracias a la acción coordinada de los subsistemas de respiración, fonación y resonancia. Estos, a su vez, deben su operatividad a la activación de diversos músculos que parecen comportarse de forma similar a aquellos que componen las extremidades. Teniendo esto en cuenta, los principios del ejercicio que han demostrado efectividad para mejorar la fuerza y resistencia de la musculatura de las extremidades podrían aplicarse al entrenamiento de la voz. En primer lugar, en este documento se presentan algunos aspectos funcionales del tejido muscular, describiendo las fibras musculares tipo I y II y puntualizando en la distribución de dichas fibras en la musculatura que hace parte de los subsistemas de la función vocal. En segundo lugar, se exponen las adaptaciones fisiológicas derivadas del ejercicio (acondiciona-miento) así como de la degeneración propia de la inactividad (desacondicionamiento). Posteriormente, se hace una explicación del enfoque de ejercitación de resistencia progresiva junto a los cinco principios que lo definen, concentrada en su aplicación a la vocología. Finalmente, se argumenta la necesidad de incluir la ciencia del ejercicio en la práctica e investigación en vocología en el contexto colombiano a la luz de algunos reportes nacionales disponibles hasta la fecha.
In recent years, vocology has focused especially in research and clinical application of evidence-based principles that enhance motor learning and motor control related to voice function. The process of voice production occurs due to coordinated action of respiration, phonation and resonance subsystems. Likewise, the function of these subsystems is a result of the activation of a variety of muscles that seem to behave similarly to skeletal limb muscles. Taking this into account, exercise principles that improve strength and endurance of skeletal limb muscles may also be applied to im-prove performance of voice production. First, this article focuses on functional aspects of muscle tissue; muscle fiber types I and II are described and, in the same way, the distribution of these fibers in voice production muscles is pointed out. Second, phy-siological adaptations to training (conditioning) as well as detraining from inactivity (deconditioning) are portrayed. Afterwards, progressive resistance training is explai-ned next to its principles and its application to vocology. Finally, the paper argues the necessity of including exercise science into practice and research of vocology in Colombian context, based on some national reports available to date
Assuntos
Fonação , Voz , Treinamento da Voz , Laringe , Respiração , Exercício Físico , Distúrbios da Voz , Fibras Musculares de Contração Lenta , Terapia por Exercício , MúsculosRESUMO
Myotomal slow-oxidative muscle (SM) powers continuous swimming and generates heat needed to maintain elevated locomotor muscle temperatures (regional endothermy) in tunas. This study describes how the amount and distribution of myotomal SM increases with fish size and age in juvenile yellowfin tuna Thunnus albacares in relationship to the development of regional endothermy. In T. albacares juveniles 40-74 mm fork length (LF ; n = 23) raised from fertilised eggs at the Inter-American Tropical Tuna Commission Achotines Laboratory in Panama and larger juveniles (118-344 mm LF ; n = 5) collected by hook and line off of Oahu, Hawaii, USA, SM was identified by histochemical staining for the mitochondrial enzyme succinic dehydrogenase or by colour (in the two largest individuals). The cross-sectional area of myotomal SM at 60% LF , a position with maximal percentage of SM in larger T. albacares, increased exponentially with LF . The percentage of total cross-sectional area composed of SM at 60% LF increased significantly with both LF and age, suggesting that SM growth occurs throughout the size range of T. albacares juveniles studied. In addition, the percentage of SM at 60% LF that is medial increased asymptotically with LF . The increases in amount of SM and medial SM, along with the development of the counter-current heat-exchanger blood vessels that retain heat, allow larger tuna juveniles to maintain elevated and relatively stable SM temperatures, facilitating range expansion into cooler waters.
Assuntos
Envelhecimento , Tamanho Corporal , Fibras Musculares de Contração Lenta/fisiologia , Músculo Esquelético/crescimento & desenvolvimento , Atum/crescimento & desenvolvimento , Animais , Havaí , Consumo de Oxigênio , Panamá , Natação , TemperaturaRESUMO
Mitochondria play an important role in providing ATP for muscle contraction. Muscle physiology is compromised in Duchenne muscular dystrophy (DMD) and several studies have shown the involvement of bioenergetics. In this work we investigated the mitochondrial physiology in fibers from fast-twitch muscle (EDL) and slow-twitch muscle (soleus) in the mdx mouse model for DMD and in control C57BL/10J mice. In our study, multiple mitochondrial respiratory parameters were investigated in permeabilized muscle fibers from 12-week-old animals, a critical age where muscle regeneration is observed in the mdx mouse. Using substrates of complex I and complex II from the electron transport chain, ADP and mitochondrial inhibitors, we found in the mdx EDL, but not in the mdx soleus, a reduction in coupled respiration suggesting that ATP synthesis is affected. In addition, the oxygen consumption after addition of complex II substrate is reduced in mdx EDL; the maximal consumption rate (measured in the presence of uncoupler) also seems to be reduced. Mitochondria are involved in calcium regulation and we observed, using alizarin stain, calcium deposits in mdx muscles but not in control muscles. Interestingly, more calcium deposits were found in mdx EDL than in mdx soleus. These data provide evidence that in 12-week-old mdx mice, calcium is accumulated and mitochondrial function is disturbed in the fast-twitch muscle EDL, but not in the slow-twitch muscle soleus.
Assuntos
Cálcio/metabolismo , Mitocôndrias/metabolismo , Contração Muscular/fisiologia , Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Lenta/metabolismo , Distrofia Muscular Animal/patologia , Trifosfato de Adenosina/biossíntese , Animais , Complexo I de Transporte de Elétrons/metabolismo , Complexo II de Transporte de Elétrons/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos mdx , Distrofia Muscular de Duchenne/patologia , Consumo de Oxigênio/fisiologia , Regeneração/fisiologiaRESUMO
Guilherme, JPLF, Egorova, ES, Semenova, EA, Kostryukova, ES, Kulemin, NA, Borisov, OV, Khabibova, SA, Larin, AK, Ospanova, EA, Pavlenko, AV, Lyubaeva, EV, Popov, DV, Lysenko, EA, Vepkhvadze, TF, Lednev, EM, Govorun, VM, Generozov, EV, Ahmetov, II, and Lancha Junior, AH. The A-allele of the FTO gene rs9939609 polymorphism is associated with decreased proportion of slow oxidative muscle fibers and over-represented in heavier athletes. J Strength Cond Res 33(3): 691-700, 2019-The purpose of this study was to explore the frequency of the FTO T > A (rs9939609) polymorphism in elite athletes from 2 cohorts (Brazil and Russia), as well as to find a relationship between FTO genotypes and muscle fiber composition. A total of 677 athletes and 652 nonathletes were evaluated in the Brazilian cohort, whereas a total of 920 athletes and 754 nonathletes were evaluated in the Russian cohort. It was found a trend for a lower frequency of A/A genotype in long-distance athletes compared with nonathletes (odds ratio [OR]: 0.65; p = 0.054). By contrast, it was found an increased frequency of the A-allele in Russian power athletes. The presence of the T/A + A/A genotypes rather than T/T increased the OR of being a Russian power athlete compared with matched nonathletes (OR: 1.45; p = 0.002). Different from that observed in combat sports athletes of lighter weight categories, the A-allele was also over-represented in combat sports athletes of heavier weight categories. The presence of the T/A + A/A genotypes rather than T/T increased the OR of being a combat sports athlete of heavier weight categories compared with nonathletes (OR: 1.79; p = 0.018). Regarding the muscle fibers, we found that carriers of the A/A genotype had less slow-twitch muscle fibers than T-allele carriers (p = 0.029). In conclusion, the A/A genotype of the FTO T > A polymorphism is under-represented in athletes more reliant on a lean phenotype and associated with decreased proportion of slow-twitch muscle fibers, while is over-represented in strength and heavier athletes.
Assuntos
Dioxigenase FTO Dependente de alfa-Cetoglutarato/genética , Atletas , Peso Corporal/fisiologia , Fibras Musculares de Contração Lenta/metabolismo , Força Muscular/fisiologia , Esportes/fisiologia , Adulto , Alelos , Brasil , Estudos de Coortes , Feminino , Genótipo , Humanos , Masculino , Estresse Oxidativo , Fenótipo , Polimorfismo de Nucleotídeo Único , Federação Russa , Adulto JovemRESUMO
Aim This study sought to investigate the effects of two different maternal high-fat diets, during gestation and lactation, on the morphology of the skeletal muscle of the adult offspring rats. METHODS: Female Wistar rats were fed Control (C) or High-fat/high-caloric (HH) or High-fat/isocaloric (HI) diet during gestation and lactation. The somatic growth of the offspring was measured throughout lactation. Glucose and insulin tolerance tests were performed at PND61 and PND65, respectively. At PND70, soleus and extensor digitorum longus (EDL) muscles were removed for myofibrillar ATPase staining analysis. KEY FINDINGS: HH pups were heavier and longer at weaning but presented same body weight at PND70. No difference among groups in glucose or insulin tolerance tests was observed. In the soleus muscle, HH offspring showed increased proportion and size of type 1 fibres and reduced proportion and number with increased size of type 2A fibres. In EDL muscle, there was no difference in proportion and number of fibres. HH and HI animals presented reduced type 1 and 2A fibres size while HH animals presented increased type 2B fibres size, in EDL muscle. SIGNIFICANCE: Maternal HH diet promoted a more oxidative profile in soleus muscle. Though, maternal high-fat/isocaloric diet influenced only fibres size. Glycolytic muscle is more resistant to maternal diet influence. These results emphasize the importance of maternal diet during the critical period of development on muscle morphology of the offspring.
Assuntos
Dieta Hiperlipídica , Fenômenos Fisiológicos da Nutrição Materna/fisiologia , Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Lenta/metabolismo , Músculo Esquelético/metabolismo , Animais , Peso Corporal/fisiologia , Dieta , Ingestão de Energia/fisiologia , Feminino , Glucose/metabolismo , Teste de Tolerância a Glucose , Insulina/metabolismo , Lactação , Masculino , Fenótipo , Gravidez , Ratos , Ratos Wistar , DesmameRESUMO
PURPOSE: Cross-sectional studies suggest that training can increase muscle carnosine (MCarn), although longitudinal studies have failed to confirm this. A lack of control for dietary ß-alanine intake or muscle fiber type shifting may have hampered their conclusions. The purpose of the present study was to investigate the effects of high-intensity interval training (HIIT) on MCarn. METHODS: Twenty vegetarian men were randomly assigned to a control (CON) (n = 10) or HIIT (n = 10) group. High-intensity interval training was performed on a cycle ergometer for 12 wk, with progressive volume (6-12 series) and intensity (140%-170% lactate threshold [LT]). Muscle carnosine was quantified in whole-muscle and individual fibers; expression of selected genes (CARNS, CNDP2, ABAT, TauT, and PAT1) and muscle buffering capacity in vitro (ßmin vitro) were also determined. Exercise tests were performed to evaluate total work done, VËO2max, ventilatory thresholds (VT) and LT. RESULTS: Total work done, VT, LT, VËO2max, and ßmin vitro were improved in the HIIT group (all P < 0.05), but not in CON (P > 0.05). MCarn (in mmol·kg dry muscle) increased in the HIIT (15.8 ± 5.7 to 20.6 ± 5.3; P = 0.012) but not the CON group (14.3 ± 5.3 to 15.0 ± 4.9; P = 0.99). In type I fibers, MCarn increased in the HIIT (from 14.4 ± 5.9 to 16.8 ± 7.6; P = 0.047) but not the CON group (from 14.0 ± 5.5 to 14.9 ± 5.4; P = 0.99). In type IIa fibers, MCarn increased in the HIIT group (from 18.8 ± 6.1 to 20.5 ± 6.4; P = 0.067) but not the CON group (from 19.7 ± 4.5 to 18.8 ± 4.4; P = 0.37). No changes in gene expression were shown. CONCLUSIONS: In the absence of any dietary intake of ß-alanine, HIIT increased MCarn content. The contribution of increased MCarn to the total increase in ßmin vitro appears to be small.
Assuntos
Carnosina/metabolismo , Treinamento Intervalado de Alta Intensidade , Músculo Esquelético/metabolismo , Adaptação Fisiológica , Limiar Anaeróbio , Distribuição da Gordura Corporal , Peso Corporal , Dieta Vegetariana , Teste de Esforço , Expressão Gênica , Humanos , Ácido Láctico/sangue , Masculino , Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Lenta/metabolismo , Consumo de Oxigênio , beta-AlaninaRESUMO
AIM: Based upon a microarray assay, we have identified that triiodothyronine (T3) upregulates MDM2 gene expression in the rat skeletal muscle. As MDM2 protein is an E3 ligase, we hypothesized that this enzyme could play a role in T3 effects on skeletal muscle mass control. METHODS: To test our hypothesis, male rats (2 months old) were randomly assigned into the following groups: intact controls, treated with 20 physiological doses of T3 for 0.5, 1 and 7 days, or with 5, 20 and 50 physiological doses of T3 for 7 days. For in vitro experiments, myotubes and C2C12 cells were treated with T3 for 3 days. RESULTS: After validation of the microarray finding throughout RT-PCR and confirmation that T3 induces increases in MDM2 protein expression in a dose-dependent manner, we observed that MDM2 was upregulated by T3 exclusively in fibre type I. Moreover, detailed histological evaluation showed that MDM2 overexpression distributes punctiformily along the cross section of the fibre and also inside nuclei. MDM2 colocalizes with PAX7 in control muscle and T3 downregulates this myogenic factor. Pharmacological inhibition of MDM2 in cultured myotubes caused a severe decrease in their diameter (~35%, P < .001 vs Control), enhancing the effect of T3 (from ~12% to ~35%, P < .001) alone upon myotube diameter and mRNA levels of atrogenes. Finally, we observed that FOXO3 (MDM2 target) is kept outside the nucleus under T3 stimulation. CONCLUSION: Our results indicate that MDM2 might be involved in the pro-trophic effects of T3 in skeletal muscle.
Assuntos
Fibras Musculares de Contração Lenta/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-mdm2/biossíntese , Tri-Iodotironina/farmacologia , Animais , Masculino , Ratos , Ratos Wistar , Ativação Transcricional/efeitos dos fármacos , Regulação para CimaRESUMO
Fatigue is a phenomenon in which force reduction has been linked to impairment of several biochemical processes. In skeletal muscle, the ATP-sensitive potassium channels (KATP) are actively involved in myoprotection against metabolic stress. They are present in sarcolemma and mitochondria (mitoKATP channels). K+ channel openers like nicorandil has been recognized for their ability to protect skeletal muscle from ischemia-reperfusion injury, however, the effects of nicorandil on fatigue in slow skeletal muscle fibers has not been explored, being the aim of this study. Nicorandil (10 µM), improved the muscle function reversing fatigue as increased post-fatigue tension in the peak and total tension significantly with respect to the fatigued condition. However, this beneficial effect was prevented by the mitoKATP channel blocker 5-hydroxydecanoate (5-HD, 500 µM) and by the free radical scavenger N-2-mercaptopropionyl glycine (MPG, 1 mM), but not by the nitric oxide (NO) synthase inhibitor Nω-nitro-L-arginine methyl ester (L-NAME, 100 µM). Nicorandil also decreased lipid peroxidation and maintained both reduced glutathione (GSH) levels and an elevated GSH/GSSG ratio, whereas total glutathione (TGSH) remained unaltered during post-fatigue tension. In addition, NO production, measured through nitrite concentrations was significantly increased with nicorandil during post-fatigue tension; this increase remained unaltered in the presence of nicorandil plus L-NAME, nonetheless, this effect was reversed with nicorandil plus MPG. Hence, these results suggest that nicorandil improves the muscle function reversing fatigue in slow skeletal muscle fibers of chicken through its effects not only as a mitoKATP channel opener but also as NO donor and as an antioxidant.
Assuntos
Glutationa/efeitos dos fármacos , Fadiga Muscular/efeitos dos fármacos , Fibras Musculares de Contração Lenta/fisiologia , Tono Muscular/efeitos dos fármacos , Nicorandil/farmacologia , Animais , Galinhas , Glutationa/metabolismo , Fibras Musculares Esqueléticas/fisiologia , Nicorandil/uso terapêutico , Óxido Nítrico/metabolismo , Oxirredução , Canais de Potássio/efeitos dos fármacos , Canais de Potássio/metabolismoRESUMO
The objective of this study was to determine and confirm the percentage of type I and type II muscle fibers that comprise the Gluteus Medius muscle in male and female canines of the German Shepherd breed, with standardized care, in different age groups, using the enzyme histochemical method. Muscle samples were collected from the Gluteus Medius muscles of forty clinically healthy dogs of the German Shepherd breed using the technique of percutaneous needle muscle biopsy. The samples were evaluated using histological and enzyme histochemical methods. The percentages of type I and II fibers and the ratio between the quantity of type I fibers/quantity of type II fibers were evaluated using the parameters of weight, age group, correlation between sex and age group, and between the sexes. It was found that there was no significant difference in relation to the types of fibers for the parameters of weight, age group, and age of the females. The correlation between the ages of the males suggested an increase in the percentage of type I fibers, a decrease in the percentage of type II fibers, or an increase in the ratio during the aging process. It was concluded that there was a decrease in the percentage of type II fibers with advancing age in male dogs, but without significant difference in the percentage of type I and type II fibers in relation to the weight. Anat Rec, 299:1540-1547, 2016. © 2016 Wiley Periodicals, Inc.
Assuntos
Fibras Musculares de Contração Rápida/citologia , Fibras Musculares de Contração Lenta/citologia , Fatores Etários , Animais , Cães , Feminino , Histocitoquímica , Masculino , Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Lenta/metabolismo , Coxa da PernaRESUMO
Two α-actin genes of the fish Leporinus macrocephalus, referring to white and red muscle tissues, were isolated. Actin isoforms, that mainly differed by a Ser/Ala155 substitution, can have a functional significance related to actin-ATP interaction. An Ala155 residue, as observed in the α-skeletal actin from red muscle, results in a decrease in actin's affinity for ATP, which may also be associated to the slow contractile performance of this tissue. Furthermore, a Phe/Ile262 substitution at the red muscle actin leads to a hydrophobicity variation at the D-plug of the protein, which could alter its stability. Data on qRT-PCR evidenced a significant higher actin mRNA level in white muscle when compared to red muscle (T=105 Mann Whitney; p<0.001). This finding could be related to the energetic demands of the white muscle tissue, with fast contraction fibers and glycolytic metabolism for energy supply. Available data on muscle actins lead to the proposal that white and red α-skeletal actins are genetically and functionally distinguishable in fish species, a feature that is not found in other vertebrate groups.
Assuntos
Actinas/química , Caraciformes , Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Lenta/metabolismo , Isoformas de Proteínas/química , Actinas/genética , Animais , Regulação da Expressão Gênica , Fibras Musculares de Contração Rápida/química , Fibras Musculares de Contração Lenta/química , Isoformas de Proteínas/genéticaRESUMO
Pacu (Piaractus mesopotamicus) is a Brazilian fish with a high economic value in pisciculture due to its rusticity and fast growth. Postnatal growth of skeletal muscle in fish occurs by hyperplasia and/or hypertrophy, processes that are dependent on the proliferation and differentiation of myoblasts. A class of small noncoding RNAs, known as microRNAs (miRNAs), represses the expression of target mRNAs, and many studies have demonstrated that miR-1, miR-133, miR-206 and miR-499 regulate different processes in skeletal muscle through the mRNA silencing of hdac4 (histone deacetylase 4), srf (serum response factor), pax7 (paired box 7) and sox6 ((sex determining region Y)-box 6), respectively. The aim of our work was to evaluate the expression of these miRNAs and their putative target mRNAs in fast- and slow-twitch skeletal muscle of pacu during growth. We used pacus in three different development stages: larval (aged 30 days), juvenile (aged 90 days and 150 days) and adult (aged 2 years). To complement our study, we also performed a pacu myoblast cell culture, which allowed us to investigate miRNA expression in the progression from myoblast proliferation to differentiation. Our results revealed an inverse correlation between the expression of the miRNAs and their target mRNAs, and there was evidence that miR-1 and miR-206 may regulate the differentiation of myoblasts, whereas miR-133 may regulate the proliferation of these cells. miR-499 was highly expressed in slow-twitch muscle, which suggests its involvement in the specification of the slow phenotype in muscle fibers. The expression of these miRNAs exhibited variations between different development stages and between distinct muscle twitch phenotypes. This work provides the first identification of miRNA expression profiles in pacu skeletal muscle and suggests an important role of these molecules in muscle growth and in the maintenance of the muscle phenotype.