Plasticidade tecidual na junção miotendínea do tibial anterior e sóleo de ratos wistar imobilizados e submetidos à reabilitação articular aquática: análises morfológicas e morfométricas
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2019-02-19
Autores
Barbosa, Juliana Cristina [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
A junção miotendínea (JMT) é a principal área anatômica do aparelho locomotor, uma interface entre o músculo e o tendão delimitada pelo sarcolema, que corresponde a principal área de transmissão de força atuante no posicionamento e estabilização articular. No entanto, a imobilização de um segmento é um recurso clínico no tratamento de lesões musculo-esqueléticas, que resulta em atrofia muscular, o que poderia indicar possíveis alterações na JMT. Em contrapartida, o exercício aeróbio tem a capacidade de modificar a morfologia da JMT e possui aplicabilidade em situações patológicas específicas com caráter preventivo e de reabilitação. O objetivo do presente estudo consistiu em analisar as possíveis alterações das características morfológicas da JMT do tibial anterior e sóleo de ratos Wistar adultos submetidos à imobilização e remobilização por protocolo de natação, empregando os métodos de Microscopia de Luz e Microscopia Eletrônica de Transmissão. Foram utilizados 35 ratos machos, com idade de 90 dias, que foram alocados em 5 diferentes grupos (n=7): Grupo Sedentário; Grupo Treinado; Grupo Imobilizado; Grupo Imobilizado/Não Treinado; Grupo Imobilizado/Treinado. Os animais de todos os grupos foram anestesiados e as amostras da JMT dissecadas. Estas amostras foram processadas para análises morfológicas por meio de técnicas de Microscopia de Luz e Microscopia Eletrônica de Transmissão. As características morfológicas do grupo Sedentário demonstraram na região da JMT as invaginações e evaginações sarcoplasmáticas que apresentaram formatos irregulares, e intercomunicações dispostas nesta região de interface paralelamente entre os feixes de miofilamentos em proximidade às linhas Z dos sarcômeros distais; No grupo Treinado foram observados na região da JMT invaginações sarcoplasmáticas espessas e amplas dispostas em contato com as evaginações; No grupo Imobilizado foi evidenciado na região da JMT aspectos característicos de atrofia do tecido muscular devido à ampla desorganização tecidual das células musculares; No grupo Imobilizado/ Não Treinado foi observado discreto remodelamento e reorganização na área da JMT, pela presença de delgadas fibras colágenas; No grupo Imobilizado/ Treinado foi evidenciado na área da JMT, a presença de longas fibras colágenas. Na região distal da célula muscular, foram observados a presença de sarcômeros em séries realinhados em relação ao eixo longitudinal da JMT. No músculo Tibial Anterior, os sarcômeros proximais do Grupo I/NT apresentaram comprimento maior em relação ao Grupo I e respectivamente ao Grupo I/T. Os sarcômeros distais do Grupo T apresentaram comprimento reduzido em relação ao Grupo S, e o Grupo I também evidenciou comprimento reduzido em relação ao Grupo S. No músculo Sóleo, os sarcômeros proximais e distais do Grupo T apresentaram comprimento reduzido em relação ao Grupo S, e o Grupo I também apresentou comprimento reduzido em relação ao Grupo S. A área da JMT apresentou amplas adaptações nas interdigitações provenientes do tecido tendíneo e uma maior área de contato quando submetida ao protocolo de treinamento de natação, em contrapartida houve redução da área de contato perante o protocolo de imobilização; a reabilitação articular pelo treinamento no grupo Imobilizado/ Treinado demonstrou uma reorganização maior dos sarcômeros em séries e reestabeleceu a área de contato entre o tecido tendíneo e o músculo esquelético, pela reestruturação das invaginações e evaginações, enquanto que o grupo Imobilizado/ Não Treinado evidenciou um discreto remodelamento.
The myotendinous junction (MTJ) is the main anatomical area of the locomotor apparatus, an interface between the muscle and the tendon delimited by the sarcolemma, which corresponds to the main area of force transmission acting on joint positioning and stabilization. However, the immobilization of a segment is a clinical feature in the treatment of musculoskeletal injuries, which results in muscle atrophy, which could indicate possible changes in MTJ. In contrast, aerobic exercise has the capacity to modify MTJ morphology and has applicability in specific pathological situations with a preventive and rehabilitation profile. The objective of the present study was to analyze the possible alterations of the MTJ morphological characteristics of the tibialis anterior and soleus of adult Wistar rats submitted to immobilization and remobilization by swimming protocol, using Light Microscopy methods and Transmission Electron Microscopy. Thirty-five male rats, aged 90 days, were allocated to 5 different groups (n = 7): Sedentary Group; Trained Group; Immobilized Group; Immobilized / Untrained Group; Immobilized / Trained Group. Animals of all groups were anesthetized and JMT samples were dissected. These samples were processed for morphological analysis using light microscopy and transmission electron microscopy techniques. The morphological characteristics of the Sedentary group demonstrated in the MTJ region the invaginations and sarcoplasmic evaginations that presented irregular and intercommunicated forms arranged in this region of interface parallel between the myofilament bundles in proximity to the Z lines of the distal sarcomeres; In the Trained group, thick and broad sarcoplasmic invaginations were observed in the MTJ region, arranged in contact with the evaginations; In the Immobilized group, characteristic features of muscle tissue atrophy were evidenced in the MTJ region due to the extensive tissue disorganization of muscle cells; In the Immobilized / Untrained group, discrete remodeling and reorganization in the MTJ area was observed due to the presence of thin collagen fibers; In the Immobilized / Trained group, the presence of long collagen fibers was evidenced in the MTJ area. In the distal region of the muscular cell, the presence of sarcomeres in series realigned in relation to the longitudinal axis of the MTJ were observed. In the tibialis anterior muscle, the proximal sarcomeres of Group I / NT presented a longer length in relation to Group I and respectively to Group I / T. The distal sarcomer of Group T presented reduced length in relation to Group S, and Group I also showed reduced length in relation to Group S. In the soleus muscle, the proximal and distal sarcomers of Group T presented reduced length in relation to Group S, and Group I also presented reduced length in relation to Group S. The MTJ area showed large adaptations in the interdigitations from the tendinous tissue and a larger contact area when submitted to the swimming training protocol; in contrast, there was a reduction of the contact area before the immobilization protocol; joint rehabilitation by training in the Fixed / Trained group demonstrated a major reorganization of the sarcomeres in series and reestablished the contact area between the tendon tissue and the skeletal muscle, by the restructuration of invaginations and evagination, while the Immobilized / Untrained group evidenced a discreet remodeling.
The myotendinous junction (MTJ) is the main anatomical area of the locomotor apparatus, an interface between the muscle and the tendon delimited by the sarcolemma, which corresponds to the main area of force transmission acting on joint positioning and stabilization. However, the immobilization of a segment is a clinical feature in the treatment of musculoskeletal injuries, which results in muscle atrophy, which could indicate possible changes in MTJ. In contrast, aerobic exercise has the capacity to modify MTJ morphology and has applicability in specific pathological situations with a preventive and rehabilitation profile. The objective of the present study was to analyze the possible alterations of the MTJ morphological characteristics of the tibialis anterior and soleus of adult Wistar rats submitted to immobilization and remobilization by swimming protocol, using Light Microscopy methods and Transmission Electron Microscopy. Thirty-five male rats, aged 90 days, were allocated to 5 different groups (n = 7): Sedentary Group; Trained Group; Immobilized Group; Immobilized / Untrained Group; Immobilized / Trained Group. Animals of all groups were anesthetized and JMT samples were dissected. These samples were processed for morphological analysis using light microscopy and transmission electron microscopy techniques. The morphological characteristics of the Sedentary group demonstrated in the MTJ region the invaginations and sarcoplasmic evaginations that presented irregular and intercommunicated forms arranged in this region of interface parallel between the myofilament bundles in proximity to the Z lines of the distal sarcomeres; In the Trained group, thick and broad sarcoplasmic invaginations were observed in the MTJ region, arranged in contact with the evaginations; In the Immobilized group, characteristic features of muscle tissue atrophy were evidenced in the MTJ region due to the extensive tissue disorganization of muscle cells; In the Immobilized / Untrained group, discrete remodeling and reorganization in the MTJ area was observed due to the presence of thin collagen fibers; In the Immobilized / Trained group, the presence of long collagen fibers was evidenced in the MTJ area. In the distal region of the muscular cell, the presence of sarcomeres in series realigned in relation to the longitudinal axis of the MTJ were observed. In the tibialis anterior muscle, the proximal sarcomeres of Group I / NT presented a longer length in relation to Group I and respectively to Group I / T. The distal sarcomer of Group T presented reduced length in relation to Group S, and Group I also showed reduced length in relation to Group S. In the soleus muscle, the proximal and distal sarcomers of Group T presented reduced length in relation to Group S, and Group I also presented reduced length in relation to Group S. The MTJ area showed large adaptations in the interdigitations from the tendinous tissue and a larger contact area when submitted to the swimming training protocol; in contrast, there was a reduction of the contact area before the immobilization protocol; joint rehabilitation by training in the Fixed / Trained group demonstrated a major reorganization of the sarcomeres in series and reestablished the contact area between the tendon tissue and the skeletal muscle, by the restructuration of invaginations and evagination, while the Immobilized / Untrained group evidenced a discreet remodeling.
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Palavras-chave
Imobilização, Remobilização aquática, Junção miotendínea, Microscopia de luz, Microscopia eletrônica de transmissão, Immobilization, Water remobilization, Myotendinous junction, Light microscopy, Transmission electron microscopy