RESUMO
INTRODUCTION AND HYPOTHESIS: Diabetes mellitus (DM) during pregnancy is associated with high levels of urinary incontinence (UI) and pelvic floor muscle dysfunction. Mild DM can lead to changes in urethral striated muscle and extracellular matrix (ECM) in pregnant rats considering both structures as an entire system responsible for urinary continence. METHODS: Ninety-two female Wistar rats were distributed in four experimental groups: virgin, pregnant, diabetic, and diabetic pregnant. In adult life, parental nondiabetic female rats were mated with nondiabetic male rats to obtain newborns. At the first day of birth, newborns received citrate buffer (nondiabetic group) or streptozotocin 100 mg/kg body weight, subcutaneous route (mild DM group). At day 21 of the pregnancy, the rats were lethally anesthetized and the urethra and vagina were extracted as a unit. Urethral and vaginal sections were cut and analyzed by: (a) cytochemical staining for ECM and muscle structural components, (b) immunohistochemistry to identify fast- and slow-muscle fibers, and (c) transmission electron microscopy for ultrastructural analysis of urethral striated muscle. RESULTS: In comparison with the three control groups, variations in the urethral striated muscle and ECM from diabetic pregnant rats were observed including thinning, atrophy, fibrosis, increased area of blood vessels, mitochondria accumulation, increased lipid droplets, glycogen granules associated with colocalization of fast and slow fibers, and a steady decrease in the proportion of fast to slow fibers. CONCLUSIONS: Mild DM and pregnancy can lead to a time-dependent disorder and tissue remodeling in which the urethral striated muscle and ECM has a fundamental function.
Assuntos
Diabetes Mellitus Experimental/patologia , Matriz Extracelular/ultraestrutura , Músculo Estriado/ultraestrutura , Uretra/patologia , Animais , Atrofia , Vasos Sanguíneos/patologia , Feminino , Fibrose , Glicogênio/ultraestrutura , Lipídeos , Mitocôndrias/patologia , Fibras Musculares de Contração Rápida/ultraestrutura , Fibras Musculares de Contração Lenta/ultraestrutura , Gravidez , Ratos Wistar , Uretra/irrigação sanguíneaRESUMO
Muscle differentiation has been widely described in zebrafish and Xenopus, but nothing is known about this process in amphibian urodeles. Both anatomical features and locomotor activity in urodeles are known to show intermediate features between fish and anurans. Therefore, a better understanding of myogenesis in urodeles could be useful to clarify the evolutionary changes that led to the formation of skeletal muscle in the trunk of land vertebrates. We report here a detailed morphological and molecular investigation on several embryonic stages of Ambystoma mexicanum and show that the first differentiating muscle fibers are the slow ones, originating from a myoblast population initially localized close to the notochord that forms a superficial layer on the somitic surface afterwards. Subsequently, fast fibers differentiation ensues. We also identified and cloned A. mexicanum Myf5 as a muscle-specific transcriptional factor likely involved in urodele muscle differentiation.
Assuntos
Ambystoma mexicanum/embriologia , Diferenciação Celular , Regulação da Expressão Gênica no Desenvolvimento , Desenvolvimento Muscular , Ambystoma mexicanum/anatomia & histologia , Ambystoma mexicanum/genética , Animais , Padronização Corporal , Clonagem Molecular , Embrião não Mamífero/embriologia , Embrião não Mamífero/ultraestrutura , Desenvolvimento Embrionário , Ensaios Enzimáticos , Imuno-Histoquímica , Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Rápida/ultraestrutura , Fibras Musculares de Contração Lenta/metabolismo , Fibras Musculares de Contração Lenta/ultraestrutura , Músculo Esquelético/embriologia , Músculo Esquelético/ultraestrutura , Mioblastos Esqueléticos/metabolismo , Fator Regulador Miogênico 5/genética , Fator Regulador Miogênico 5/metabolismo , Miosinas/genética , Miosinas/metabolismo , Notocorda/embriologia , Notocorda/ultraestrutura , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismoRESUMO
The aim of the study was to analyze the muscle fibers by histochemistry and morphometric methods from patients with Duchenne muscular dystrophy (DMD). Muscle biopsies were taken from the vastus lateralis muscle of five boys between 13 and 15-years of age, with clinical diagnosis of DMD. The histochemistry was performed using myofibrillar ATPases (9.6, 4.6 and 4.3). To morphometrical analysis a computerized semiautomatic system and software Image-Lab was used. ATPase staining showed atrophy of muscle fibers. Fibrosis and adipose deposition occurred in variable degree depending of muscular involvement. The morphometrical analysis showed an increase of size (percentage) to type I fiber than other types in all patients. Furthermore, the type I fiber had a larger cross-sectional area and mean diameter than type IIa and IIb fibers. Both histochemistry and morphometric analysis could be important tools for qualitative and quantitative diagnostics of muscle fibers attacked in this type of disease.
El objetivo del estudio fue analizar las fibras musculares mediante histoquímica y métodos morfométricos en pacientes con distrofia muscular de Duchenne (DMD). Se tomaron biopsias musculares del músculo vasto lateral de cinco niños entre 13 y 15 años de edad, con diagnóstico clínico de DMD. La histoquímica se realizó mediante ATPasa miofibrilar (9.6, 4.6 y 4.3). Para el análisis morfométrico se utilizó un sistema semiautomático computarizado y software de imagen de laboratorio. La tinción de ATPasa mostró una atrofia de las fibras musculares. La fibrosis y depósito adiposo se observó en grado variable dependiendo del compromiso muscular. El análisis morfométrico mostró un aumento de tamaño (porcentaje) de fibras tipo I en todos los pacientes. Además, la fibra tipo I tuvo un área de sección transversal y diámetro medio mayor que las fibras tipos IIa y IIb. Tanto la histoquímica y el análisis morfométrico pueden ser herramientas importantes para el diagnóstico cualitativo y cuantitativo de las fibras musculares comprometidas en este tipo de enfermedad.
Assuntos
Criança , Distrofia Muscular de Duchenne/cirurgia , Distrofia Muscular de Duchenne/diagnóstico , Distrofia Muscular de Duchenne/fisiopatologia , Distrofia Muscular de Duchenne/genética , Distrofia Muscular de Duchenne/microbiologia , Fibras Musculares de Contração Lenta/citologia , Fibras Musculares de Contração Lenta/classificação , Fibras Musculares de Contração Lenta/química , Fibras Musculares de Contração Lenta/ultraestrutura , Histocitoquímica/métodos , Técnicas Histológicas/métodosRESUMO
We investigated whether veratrine (5 microl, 10 ng/kg) injected into the mouse extensor digitorum longus (EDL) (fast-twitch) and soleus (SOL) (slow-twitch) muscles provokes distinctive ultrastructural disturbances 15, 30 and 60 min later. The mitochondria in SOL were affected earlier (within 15 min) than in EDL. Swelling of the sarcoplasmic reticulum terminal cisternae was more marked in EDL than in SOL and caused distortion of sarcomeres so that fragmentation of myofilaments was more pronounced in EDL. Hypercontracted sarcomeres were seen mainly in SOL and veratrine caused infoldings of the sarcolemma only in this muscle. In both muscles, the T-tubules remained unaffected and by 60 min after veratrine most of the above alterations had reverted to normal. Pretreatment with tetrodotoxin prevented the alterations induced by veratrine. This suggests that most of the alterations resulted from the enhanced influx of Na+ into muscle fibers. These results emphasize the importance of considering the type of muscle when studying the action of myotoxic agents.
Assuntos
Músculo Esquelético/efeitos dos fármacos , Doenças Musculares/induzido quimicamente , Veratrina/toxicidade , Animais , Antagonismo de Drogas , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/ultraestrutura , Fibras Musculares de Contração Rápida/efeitos dos fármacos , Fibras Musculares de Contração Rápida/ultraestrutura , Fibras Musculares de Contração Lenta/efeitos dos fármacos , Fibras Musculares de Contração Lenta/ultraestrutura , Músculo Esquelético/ultraestrutura , Doenças Musculares/patologia , Sarcômeros/efeitos dos fármacos , Sarcômeros/ultraestrutura , Tetrodotoxina/farmacologiaRESUMO
The purpose of the present work was to study some morphological differences of similar muscle fiber types--classified by ATPase reactions in different muscles of rats. Morphological parameters were used as stereological techniques at light and electron microscopic level. There was a great variation in the diameter of each muscle fiber type of different muscles. The smallest diameter of type 1 myofibers of the soleus was greater than the diameter of type 1 myofibers of other muscles. The diameter of type 1 myofibers of the soleus and of the lateral part of the gastrocnemius was almost twice the diameter of type 1 myofibers of sternocleidomastoid. The lateral and medial parts of gastrocnemius had the largest 2A and 2B muscle fibers. As a whole, among the studied muscles, myofibers of postural muscles of the posterior parts of the posterior limbs had the greatest diameter. Stereological analysis at electron microscopic level revealed that there were differences in the volume density of mitochondria in the different muscles. The quantity of mitochondria was greater in the diaphragm than in the gastrocnemius, soleus and sternocleidomastoid muscles. Our results suggested that the diameter of muscle fibers is more related to the resistance the muscle is submitted than to the continuous necessity of contraction. However, the quantity of mitochondria of oxidative fibers of the diaphragm would be related to continuous necessity of contraction and high oxidative necessity of this muscle.
Assuntos
Fibras Musculares de Contração Rápida/ultraestrutura , Fibras Musculares de Contração Lenta/ultraestrutura , Músculo Esquelético/ultraestrutura , Adenosina Trifosfatases/metabolismo , Animais , Histocitoquímica , Mitocôndrias/ultraestrutura , Fibras Musculares de Contração Rápida/enzimologia , Fibras Musculares de Contração Lenta/enzimologia , Músculo Esquelético/enzimologia , Ratos , Ratos WistarRESUMO
The effects of veratrine have been investigated in mammalian, amphibian, and crustacean muscle, but not in fish. In this work, the action of veratrine was studied in the lateral muscle of the freshwater teleost Oreochromis niloticus after intramuscular injection. Histoenzymological typing and electron microscopy of muscle fibers before and 15, 30, and 60 min after veratrine injection (10 ng/kg fish) were used to indirectly assess the morphological changes and the oxidative and m-ATPase activities. In some cases, muscles were pretreated with tetrodotoxin to determine whether the ultrastructural changes were the result of Na(+) channel activation by veratrine. Veratrine altered the metabolism of fibers mainly after 30 min. Oxidative fibers showed decreased NADH-TR activity, whereas that of glycolytic and oxidative-glycolytic type fibers increased. There was no change in the m-ATPase activity of the three fiber types, except at 60 min postveratrine, when a novel fiber type, which showed no reversal after acidic and alkaline preincubations, appeared. Ultrastructural damage involved sarcomeres, myofibrils, and mitochondria, but the T-tubules remained intact. Pretreatment with tetrodotoxin (1 ng/ml) prevented the ultrastructural changes caused by veratrine. These results show that in fish skeletal muscle veratrine produces some effects that are not seen in mammalian muscle.
Assuntos
Ciclídeos , Músculo Esquelético/efeitos dos fármacos , Veratrina/toxicidade , Adenosina Trifosfatases/metabolismo , Antagonismo de Drogas , Injeções Intramusculares , Microscopia Eletrônica , Mitocôndrias Musculares/efeitos dos fármacos , Mitocôndrias Musculares/ultraestrutura , Fibras Musculares de Contração Rápida/efeitos dos fármacos , Fibras Musculares de Contração Rápida/enzimologia , Fibras Musculares de Contração Rápida/ultraestrutura , Fibras Musculares de Contração Lenta/efeitos dos fármacos , Fibras Musculares de Contração Lenta/enzimologia , Fibras Musculares de Contração Lenta/ultraestrutura , Músculo Esquelético/enzimologia , Músculo Esquelético/ultraestrutura , Sarcômeros/efeitos dos fármacos , Sarcômeros/ultraestrutura , Tetrodotoxina/toxicidade , Veratrina/administração & dosagemRESUMO
El presente trabajo estudia la hipertrofia maseterina desde el punto de vista ultraestructural del músculo masetero con hipertrofia. Para el mismo se toma una muestra de los músculos que presentan esta condición en 13 pacientes que acudieron a la Facultad de Odontología de la UCV. Las muestras de los pacientes con hipertrofia maseterina diagnosticada clínicamente, se observaron al miscroscopio electrónico. En el estudio se reportan hallazgos que hacen inferir que se está en presencia de una seudohipertrofia más que una hipertrofia verdadera. Se presentan los resultados parciales de esta investigación como aporte al estudio ultraestructural de los músculos masticatorios creando nuevas rutas en la investigación, en este renglón
Assuntos
Humanos , Masculino , Feminino , Hipertrofia/patologia , Músculo Masseter/patologia , Músculo Masseter/ultraestrutura , Biópsia , Histocitoquímica/métodos , Microscopia Eletrônica/métodos , Fibras Musculares de Contração Rápida/ultraestrutura , Fibras Musculares de Contração Lenta/ultraestrutura , Músculos da Mastigação/patologiaRESUMO
Biopsies from soleus and extensor digitorum longus (EDL) muscles obtained in rats with an experimental chloroquine myopathy were studied ultrastructurally. Two different histopathological pictures were observed: type I fibres from soleus exhibited a vacuolar myopathy with an almost normal sarcomeric structure; type II fibres from EDL did not show vacuoles but changes similar to neurogenic atrophy. Our results suggest that chloroquine produces direct toxic effects in type I fibres and secondary neurogenic damage in type II fibres.