Plasticity at the myotendinous junction of adult rats subjected to stretching, associated with hypertrophy and swimming training: morphological, molecular and functional analyzes, with new perspectives about sarcomerogenesis

Abstract

The myotendinous junction (MTJ) is the main anatomical area of the locomotor apparatus, which comprises the region of interface between muscles and tendons. The main function of MTJ is to transmit the forces generated in muscle contractions by the contractile proteins present in myofibrils to the connective tissue proteins of the tendon during movement. Stretching is a physical activity that, through the longitudinal passive tensional force, causes a mechanical stimulus that determines muscular hypertrophy. Resistance training is recognized both in scientific and clinical practice, due to its health benefits, functional capacity and increase in quality of life. Aerobic exercise has the capacity to promote morphological changes in the MTJ and its applicability in specific pathological situations with a preventive and rehabilitation character. The present study will analyze the possible alterations of the morphological, molecular and functional characteristics in the myotendinous junction of the tibialis anterior and soleus of adult Wistar rats that will be submitted to static stretching previously and associated to different protocols: muscular hypertrophy training and swimming training. Ninety adult Wistar rats, 90 days aged, allocated in 6 different groups will be used: Sedentary Group; Stretched Group; Stretched / hypertrophy Trained Group; Stretched / Trained Swimming Group; Hypertrophy Training Group; Group Trained Swimming. These samples will be processed for morphological and molecular analyzes for the use of light microscopy, immunofluorescence, Western blot assays, transmission electron microscopy, PCR - Real Time, and functional analysis. The results of the present study may contribute to elucidate the possible alterations in the MTJ morphology of Wistar rats, with future purpose of actions in the prevention of injuries and in applications of new rehabilitation protocols. (AU)