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1.
Artigo em Inglês | MEDLINE | ID: mdl-24365169

RESUMO

Pacu (Piaractus mesopotamicus) is a fast-growing fish that is extensively used in Brazilian aquaculture programs and shows a wide range of thermal tolerance. Because temperature is an environmental factor that influences the growth rate of fish and is directly related to muscle plasticity and growth, we hypothesized that different rearing temperatures in juvenile pacu, which exhibits intense muscle growth by hyperplasia, can potentially alter the muscle growth patterns of this species. The aim of this study was to analyze the muscle growth characteristics together with the expression of the myogenic regulatory factors MyoD and myogenin and the growth factor myostatin in juvenile pacu that were submitted to different rearing temperatures. Juvenile fish (1.5 g weight) were distributed in tanks containing water and maintained at 24°C (G24), 28 °C (G28) and 32 °C (G32) (three replicates for each group) for 60 days. At days 30 and 60, the fish were anesthetized and euthanized, and muscle samples (n=12) were collected for morphological, morphometric and gene expression analyses. At day 30, the body weight and standard length were lower for G24 than for G28 and G32. Muscle fiber frequency in the <25 µm class was significantly higher in G24, and the >50 µm class was lower in G24. MyoD gene expression was higher in G24 compared with that in G28 and G32, and myogenin and myostatin mRNA levels were higher in G24 than G28. At day 60, the body weight and the standard length were higher in G32 but lower in G24. The frequency distribution of the <25 µm diameter muscle fibers was higher in G24, and that of the >50 µm class was lower in G24. MyoD mRNA levels were higher in G24 and G32, and myogenin mRNA levels were similar between G24 and G28 and between G24 and G32 but were higher in G28 compared to G32. The myostatin mRNA levels were similar between the studied temperatures. In light of our results, we conclude that low rearing temperature altered the expression of muscle growth-related genes and induced a delay in muscle growth in juvenile pacu (P. mesopotamicus). Our study provides a clear example of thermally induced phenotypic plasticity in pacu fish and shows that changing the rearing temperature during the juvenile stage can have a considerable effect on gene expression and muscle growth in this species.


Assuntos
Caraciformes/genética , Temperatura Alta , Músculos/metabolismo , Animais , Caraciformes/crescimento & desenvolvimento , Expressão Gênica , Desenvolvimento Muscular , Proteína MyoD/genética , Proteína MyoD/metabolismo , Miogenina/genética , Miogenina/metabolismo , Miostatina/genética , Miostatina/metabolismo
2.
Comp Biochem Physiol B Biochem Mol Biol ; 164(4): 268-74, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23416085

RESUMO

Muscle growth mechanisms are controlled by molecular pathways that can be affected by fasting and refeeding. In this study, we hypothesized that short period of fasting followed by refeeding would change the expression of muscle growth-related genes in juvenile Nile tilapia (Oreochromis niloticus). The aim of this study was to analyze the expression of MyoD, myogenin and myostatin and the muscle growth characteristics in the white muscle of juvenile Nile tilapia during short period of fasting followed by refeeding. Juvenile fish were divided into three groups: (FC) control, feeding continuously for 42 days, (F5) 5 days of fasting and 37 days of refeeding, and (F10) 10 days of fasting and 32 days of refeeding. At days 5 (D5), 10 (D10), 20 (D20) and 42 (D42), fish (n=14 per group) were anesthetized and euthanized for morphological, morphometric and gene expression analyses. During the refeeding, fasted fish gained weight continuously and, at the end of the experiment (D42), F5 showed total compensatory mass gain. After 5 and 10 days of fasting, a significant increase in the muscle fiber frequency (class 20) occurred in F5 and F10 compared to FC that showed a high muscle fiber frequency in class 40. At D42, the muscle fiber frequency in class 20 was higher in F5. After 5 days of fasting, MyoD and myogenin gene expressions were lower and myostatin expression levels were higher in F5 and F10 compared to FC; at D42, MyoD, myogenin and myostatin gene expression was similar among all groups. In conclusion, this study showed that short periods of fasting promoted muscle fiber atrophy in the juvenile Nile tilapia and the refeeding caused compensatory mass gain and changed the expression of muscle growth-related genes that promote muscle growth. These fasting and refeeding protocols have proven useful for understanding the effects of alternative warm fish feeding strategies on muscle growth-related genes.


Assuntos
Ciclídeos/metabolismo , Músculo Esquelético/metabolismo , Animais , Peso Corporal , Ciclídeos/genética , Ciclídeos/crescimento & desenvolvimento , Jejum/metabolismo , Expressão Gênica , Músculo Esquelético/crescimento & desenvolvimento , Proteína MyoD/metabolismo , Miogenina/metabolismo , Miostatina/metabolismo , RNA Mensageiro/metabolismo
3.
J Mol Histol ; 43(5): 461-71, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22538480

RESUMO

Stimuli during pregnancy, such as protein restriction, can affect morphophysiological parameters in the offspring with consequences in adulthood. The phenomenon known as fetal programming can cause short- and long-term changes in the skeletal muscle phenotype. We investigated the morphology and the myogenic regulatory factors (MRFs) MyoD and myogenin expression in soleus, SOL; oxidative and slow twitching and in extensor digitorum longus, EDL; glycolytic and fast twitching muscles in the offspring of dams subjected to protein restriction during pregnancy. Four groups of male Wistar offspring rats were studied. Offspring from dams fed a low-protein diet (6 % protein, LP) and normal protein diet (17 % protein, NP) were euthanized at 30 and 112 days old, and their muscles were removed and kept at -80 °C. Muscles histological sections (8 µm) were submitted to a myofibrillar adenosine triphosphatase histochemistry reaction for morphometric analysis. Gene and protein expression levels of MyoD and myogenin were determined by RT-qPCR and western blotting. The major findings observed were distinct patterns of morphological changes in SOL and EDL muscles in LP offspring at 30 and 112 days old without changes in MRFs MyoD and myogenin expression. Our results indicate that maternal protein restriction followed by normal diet after birth induced morphological changes in muscles with distinct morphofunctional characteristics over the long term, but did not alter the MRFs MyoD and myogenin expression. Further studies are necessary to better understand the mechanisms underlying the maternal protein restriction response on skeletal muscle.


Assuntos
Desenvolvimento Fetal , Músculo Esquelético , Proteína MyoD , Miogenina , Animais , Dieta com Restrição de Proteínas , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Músculo Esquelético/crescimento & desenvolvimento , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , Proteína MyoD/genética , Proteína MyoD/metabolismo , Miogenina/genética , Miogenina/metabolismo , Gravidez , Complicações na Gravidez/metabolismo , Ratos , Ratos Wistar
4.
Anat Rec (Hoboken) ; 294(8): 1393-400, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21714108

RESUMO

The aim of this study was to test whether high-intensity resistance training with insufficient recovery time between bouts, could result in a decrease of muscle fiber cross-sectional area (CSA), alter fiber-type frequencies and myosin heavy chain (MHC) isoform content in rat skeletal muscle. Wistar rats were divided into two groups: trained (Tr) and control (Co). Tr group were subjected to a high-intensity resistance training program (5 days/week) for 12 weeks, involving jump bouts into water, carrying progressive overloads based on percentage body weight. At the end of experiment, animals were sacrificed, superficial white (SW) and deep red (DR) portions of the plantaris muscle were removed and submitted to mATPase histochemical reaction and SDS-PAGE analysis. Throughout the experiment, both groups increased body weight, but Tr was lower than Co. There was a significant reduction in IIA and IID muscle fiber CSA in the DR portion of Tr compared to Co. Muscle fiber-type frequencies showed a reduction in Types I and IIA in the DR portion and IID in the SW portion of Tr compared to Co; there was an increase in Types IIBD frequency in the DR portion. Change in muscle fiber-type frequency was supported by a significant decrease in MHCI and MHCIIa isoforms accompanied by a significant increase in MHCIIb isoform content. MHCIId showed no significant differences between groups. These data show that high-intensity resistance training with insufficient recovery time between bouts promoted muscle atrophy and a transition from slow-to-fast contractile activity in rat plantaris muscle.


Assuntos
Músculo Esquelético/metabolismo , Atrofia Muscular/etiologia , Cadeias Pesadas de Miosina/metabolismo , Treinamento Resistido/efeitos adversos , Adenosina Trifosfatases/metabolismo , Animais , Eletroforese em Gel de Poliacrilamida , Masculino , Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Lenta/metabolismo , Músculo Esquelético/patologia , Músculo Esquelético/fisiopatologia , Atrofia Muscular/metabolismo , Atrofia Muscular/patologia , Atrofia Muscular/fisiopatologia , Ratos , Ratos Wistar , Recuperação de Função Fisiológica , Coloração e Rotulagem , Fatores de Tempo , Aumento de Peso
5.
J Mol Histol ; 42(3): 205-15, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-21509445

RESUMO

Heart failure (HF) is characterized by limited exercise tolerance, skeletal muscle atrophy, a shift toward fast muscle fiber, and myogenic regulatory factor (MRF) changes. Reactive oxygen species (ROS) also contribute to target organ damage in this syndrome. In this study, we investigated and compared morphofunctional characteristics and gene expression in Soleus (SOL--oxidative and slow twitching muscle) and in Extensor Digitorum Longus (EDL--glycolytic and fast twitching muscle) during HF. Two groups of rats were used: control (CT) and heart failure (HF), induced by a single injection of monocrotaline. MyoD and myogenin gene expression were determined by RT-qPCR, and MHC isoforms by SDS-PAGE; muscle fiber type frequency and cross sectional area (CSA) were analyzed by mATPase. A biochemical study was performed to determine lipid hydroperoxide (LH), glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD); myography was used to determine amplitude, rise time, fall time, and fatigue resistance in both muscles. HF showed SOL and EDL muscle atrophy in all muscle fiber types; fiber frequency decreased in type IIC and muscle contraction fall time increased only in SOL muscle. Myogenin mRNA expression was lower in SOL and myoD decreased in HF EDL muscle. LH increased, and SOD and GSH-Px activity decreased only in HF SOL muscle. HF EDL muscle did not present changes in MHC distribution, contractile properties, HL concentration, and antioxidant enzyme activity. In conclusion, our results indicate that monocrotaline induced HF promoted more prominent biochemical, morphological and functional changes in SOL (oxidative and slow twitching muscle). Although further experiments are required to better determine the mechanisms involved in HF pathophysiology, our results contribute to understanding the muscle-specific changes that occur in this syndrome.


Assuntos
Regulação da Expressão Gênica , Insuficiência Cardíaca/induzido quimicamente , Insuficiência Cardíaca/fisiopatologia , Monocrotalina , Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Lenta/metabolismo , Animais , Masculino , Contração Muscular/fisiologia , Fibras Musculares de Contração Rápida/patologia , Fibras Musculares de Contração Lenta/patologia , Atrofia Muscular/metabolismo , Atrofia Muscular/patologia , Proteína MyoD/genética , Miogenina/genética , RNA Mensageiro/genética , Ratos , Ratos Wistar
6.
Braz. j. morphol. sci ; 23(2): 263-270, Apr.-June 2006. tab, ilus
Artigo em Inglês | LILACS | ID: lil-468062

RESUMO

Bovine skeletal muscle growth characteristics and muscle fiber type frequency are of primary interest because they both play a fundamental role in modeling meat quality and tenderness, although the precise relationship remains undefined. Growth promoters like rbST have been reported to have varying effects on muscle growth performance. The objective of this experiment was to evaluate the histochemistry and growth characteristics of bovine semitendinosus muscle treated with rbST. Animals were divided into two groups: control (saline-injected; n=8) and rbST-injected (15 ug/kg; n=8). Heifers were injected every 14 days from day 210 until day 285 of age. Muscle samples were collected (day 210 and 360) and frozen in liquid nitrogen. Histological sections (10 um) underwent morphological and histochemical analysis (HE, NADH-TR and mATPase), morphometry (fiber area and distribution), and biochemical analysis. Fibers were classified as SO, FOG, and FG. FOG fiber percentage distribution decreased and cross-sectional area increased in rbSTtreated animals. Recombinant bST caused a greater animal body weight gain and FOG fiber hypertrophy, while contributing to a decrease in FOG fiber distribution. We conclude that the phenotypic modulation seen in this muscle fiber suggests a potential role of this muscle in modeling the meat quality.


Assuntos
Animais , Hormônio do Crescimento , Hormônio do Crescimento/administração & dosagem , Hormônio do Crescimento/metabolismo , Desenvolvimento Muscular , Fibras Musculares Esqueléticas , Bovinos/anatomia & histologia , Histocitoquímica , Fibras Musculares Esqueléticas
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