Histochemical study of the extensor digitorum longus and soleus muscles in alcoholic rats

The extensor digitorum longus (EDL) and soleus (SOL) muscle fibres from albino rats submitted to experimental chronic alcoholism were evaluated in accordance with their metabolic and morphometric profiles. Twenty-seven male animals aged 4 months and weighing approximately 400 g were used. The animals were divided into three groups: control, isocaloric and alcoholic and sacrifices were carried out after 5, 10 and 15 months. The muscles were dissected, removed, cross-sectioned in a cryostat and submitted to the NADH (nicotinamide adenine dinucleotide) reaction. The SO (slow-twitch-oxidative), FG (fast-twitch-glycolytic) and FOG (fast-twitch-oxidative-glycolytic) muscle fibre types exhibited a polygonal, triangular or rounded shape and did not present noteworthy modifications in either muscles during the study. The cross-sectional areas of the fibres from the studied muscles did not present significant differences during the observations. Fibre area behaved similarly in the alcoholic animals up to the 10th month, i.e. it was decreased, as also observed in the other groups. At 15 months, however, all fibres were increased, with a predominance of FG fibres in the SOL muscle. Changes in fibre population were observed mainly in the SOL muscle of alcoholic animals: SO fibres were initially increased in number but decreased after the 10th month, and the opposite was observed for the population of FG fibres. FOG fibres increased linearly in number throughout the experiment. The statistical analysis showed nevertheless that the fibre population and cross-sectional area changes were not significant. In the alcoholic animals quantitative variations of muscle fibres were more evident in the SOL muscle, suggesting that the SOL muscle is more sensitive to the toxic action of ethanol. The results concerning the increased fibre diameter in alcoholic animals would be associated with muscle oedema induced directly or indirectly by the ethanol.

Decreased rate of protein synthesis, caspase-3 activity, and ubiquitin-proteasome proteolysis in soleus muscles from growing rats fed a low-protein, high-carbohydrate diet

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Efeito da espasticidade sobre os padrões lineares de marcha em hemiparéticos

INTRODUÇÃO: A hemiparesia após o acidente vascular encefálico (AVE) é a sequela mais frequente, prejudicando a velocidade de execução dos movimentos automáticos, diminuindo a autonomia do indivíduo e gerando incapacidade. OBJETIVOS: Analisar o efeito da espasticidade nos padrões lineares de marcha (PLM) em indivíduos hemiparéticos. MÉTODOS: Foram estudados dois grupos: 20 indivíduos com AVE (G1) e 20 indivíduos sadios, destros, sem sequela neurológica (G2), com média de idade de 54,2 e 52,6 anos respectivamente. Foram avaliados os PLM pelo protocolo de Nagazaki, o tônus muscular pela escala de Ashworth modificada e o arco de movimento por goniometria. Foi feita comparação dos parâmetros nos dois grupos pelo teste t de Student e correlação de Spearman com nível de significância de 5%. RESULTADOS: A média da distância foi de 14,52 m e 32,16 m, e o tempo foi de 23,75 s e 19,02 s no G1 e G2 respectivamente (p < 0,0001). Na comparação entre os grupos, a amplitude média de passo e a velocidade média foram estatisticamente significantes (p < 0,05) e a cadência não mostrou significância (p = 0,1936). Quando os PLM foram comparados com o grau de espasticidade dos músculos gastrocnêmio e sóleo, mostraram associação negativa com distância, amplitude de passo e velocidade e associação positiva com o tempo (p < 0,05). CONCLUSÃO: Quanto maior o grau de espasticidade dos músculos gastrocnêmio e sóleo, menores serão os parâmetros lineares de marcha do indivíduo com sequela de hemiparesia pós-AVE.

The neurotoxicological effects of mastoparan Polybia-MPII at the murine neuromuscular junction: an ultrastructural and immunocytochemical study

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effects of nandrolone decanoate and resistance exercise on skeletal muscle in adult male rats

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Histochemical and SEM evaluation of the neuromuscular junctions from alcoholic rats

In the present study morphological changes occurring in the neuromuscular junctions (NMJ) of the extensor digitorum longus (EDL) and soleus muscles from albino rats (Rattus norvegicus) submitted to experimental chronic alcoholism were evaluated. Seventy two male animals aged 4 months and weighing on average 400 g were divided into three groups: control, alcoholic and isocaloric. Six rats from each group were anesthetized and sacrificed after 5, 10, 15 and 18 months. The NMJ did not show detectable morphological changes in either muscle after treatment when examined by light microscopy. With respect to the dimensions, statistical analysis demonstrated a tendency to a statistically significant treatment x time interaction for the length of soleus muscle NMJ. The ultrastructural study, however, revealed that the NMJ of the soleus muscle of animals submitted to 18 months of experimental alcoholism presented important morphological alterations. Characteristically, the NMJ of these muscles is located on an elevation on the surface of the muscle fiber, presenting a regular round, oval or elliptical shape and continuous and not very deep synaptic grooves. Approximately 30% of the NMJ of alcoholic rats are irregular in shape, with the sarcolemmal elevations typical of the synapse region being flattened on at least one side, with discontinuous synaptic grooves, and deep and punctiform contacts of the synaptic buds. These data suggest that, although skeletal muscle has a greater natural resistance against the direct or indirect effects of alcohol, some submicroscopic morphological alterations are detectable in the NMJ, especially in muscles with oxidative metabolism (soleus) following long periods of ingestion of alcohol. (C) 2002 Elsevier B.V. Ltd. All rights reserved.

Low-intensity resistance training attenuates dexamethasone-induced atrophy in the flexor hallucis longus muscle

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efeitos do uso de Decanoato de Nandrolona sobre a junção neuromuscular de ratos em processo de envelhecimento submetidos ao exercício resistido

Pós-graduação em Bases Gerais da Cirurgia - FMB

Stretch Injuries of Skeletal Muscles: Experimental Study in Rats' Soleus Muscle

The study aimed to verify the physiological injury behavior by stretching the soleus muscle of rats, using a noninvasive experimental model. Twenty-four rats were used and divided into three groups of eight animals: control group (A), group that performed tetanus followed by electrical stimulation and a sudden dorsiflexion of the left paw performed by a device equipped with a mechanism of muscle soleus rapid stretching (B); and a group that only received the tetanus (C). Three days later, the animals were killed, and the soleus muscle was resected and divided into three segments. Morphological changes indicative of muscle damage appeared in all three segments of group B. In a lesser degree, similar changes were also detected in muscles subjected to only tetanus. This model was effective; reproducing an injury similar to what occurs in human sports injuries.

Myostatin and follistatin expression in skeletal muscles of rats with chronic heart failure

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Guanidine Affects Differentially the Twitch Response of Diaphragm, Extensor Digitorum Longus and Soleus Nerve-Muscle Preparations of Mice

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Mouse extensor digitorum longus and soleus show distinctive ultrastructural changes induced by veratrine

We investigated whether veratrine (5 μl, 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.

Electromyographic patterns of lower limb muscles during apprehensive gait in younger and older female adults

Objective: Investigate the influence of apprehensive gait on activation and cocontraction of lower limb muscles of younger and older female adults. Methods: Data of 17 younger (21.47±2.06 yr) and 18 older women (65.33±3.14. yr) were considered for this study. Participants walked on the treadmill at two different conditions: normal gait and apprehensive gait. The surface electromyographic signals (EMG) were recorded during both conditions on: rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), tibialis anterior (TA), gastrocnemius lateralis (GL), and soleus (SO). Results: Apprehensive gait promoted greater activation of thigh muscles than normal gait (F=5.34 and p=0.007, for significant main effect of condition; RF, p=0.002; VM, p<0.001; VL, p=0.003; and BF, p=0.001). Older adults had greater cocontraction of knee and ankle stabilizer muscles than younger women (F=4.05 and p=0.019, for significant main effect of groups; VM/BF, p=0.010; TA/GL, p=0.007; and TA/SO, p=0.002). Conclusion: Apprehensive gait promoted greater activation of thigh muscles and older adults had greater cocontraction of knee and ankle stabilizer muscles. Thus, apprehensive gait may leads to increased percentage of neuromuscular capacity, which is associated with greater cocontraction and contribute to the onset of fatigue and increased risk of falling in older people. © 2013 Elsevier Ltd.

Downhill running excessive training inhibits hypertrophy in mice skeletal muscles with different fiber type composition

The aim of this study was to verify the effects of running overtraining protocols performed in downhill, uphill, and without inclination on the proteins related to hypertrophy signaling pathway in extensor digitorum longus (EDL) and soleus of C57BL/6 mice. We also performed histological and stereological analyses. Rodents were divided into control (CT; sedentary mice), overtrained by downhill running (OTR/down), overtrained by uphill running (OTR/up), and overtrained by running without inclination (OTR). The incremental load, exhaustive, and grip force tests were used as performance evaluation parameters. 36 h after the grip force test, EDL and soleus were removed and immediately used for immunoblotting analysis or stored at -80°C for histological and stereological analyses. For EDL, OTR/down decreased the protein kinase B (Akt) and tuberous sclerosis protein 2 (TSC2) phosphorylation (p), and increased myostatin, receptor-activated Smads (pSMAD2-3), and insulin receptor substrate-1 (pIRS-1; Ser307/636). OTR/down also presented low and high relative proportions of cytoplasm and connective tissue, respectively. OTR/up increased the mammalian target of rapamycin (pmTOR), 70-kDa ribosomal protein S6 kinase 1 (pS6K1) and pSMAD2-3, and decreased pTSC2. OTR decreased pTSC2 and increased pIRS-1 (Ser636). For soleus, OTR/down increased S6 ribosomal protein (pS6RP) and pSMAD2-3, and decreased pIRS-1 (Ser639). OTR/up decreased pS6K1, pS6RP and pIRS-1 (Ser639), and increased pTSC2 (Ser939), and pSMAD2-3. OTR increased pS6RP, 4E-binding protein-1 (p4E-BP1), pTSC2 (Ser939), and pSMAD2-3, and decreased pIRS-1 (Ser639). In summary, OTR/down inhibited the skeletal muscle hypertrophy with concomitant signs of atrophy in EDL. The effects of OTR/up and OTR depended on the analyzed skeletal muscle type. J. Cell. Physiol. 9999: 1-12, 2015. © 2015 Wiley Periodicals, Inc.

Muscles-bearing of sting apparatus in social wasps and their relationship with the autotomy (Hymenoptera: Vespidae: Polistinae)

The musculature that sustains the stinging organ was studied in three species of social wasps using scanning electron microscopy technique. It were observed some differences among species in which sting autotomy occurs and in which it does not. These differences were related to the diameter,length and position of insertion of these muscles.