Morphology and MRFs expression of the skeletal muscle of rats submitted to stimulus atrophy and recovery for physical training

Abstract

Recent research advances in understanding the cellular and molecular mechanisms that underlie the processes of hypertrophy and atrophy. This may contribute to development of effective therapeutic strategies to attenuate or block the loss of muscle tissue associated with aging and pathological conditions. In this context, myogenic factors that control the activity of satellite cells have been studied to better understand the events involved in the recovery of muscle mass. Among them, we highlight the Myogenic Regulatory Factors (MRFs), which have been described as potential mediators of muscle growth. The objectives of this study will evaluate the morphofunctional adaptations and gene expression of MRFs (MyoD and myogenin) in skeletal muscle (soleus) subjected to an atrophic stimulus followed by physical training. Will be used 64 male Wistar rats (80 days, 250 to 300 g), divided into 8 groups (n = 8): C: control animals a week, I: Animals immobilized a week, C3: control animals 3 days; R3: Animals immobilized and recovered for 3 days, T3: Animals immobilized and submitted to exercise for 3 days; C7: Animals controls 7 days; R7: Animals immobilized and subsequently recovered by 7 days, T7: Animals immobilized and subsequently subjected to exercise for 7 days. Initially, the animals in groups I, R3, R7, T3 and T7, will undergo a 7 days of immobilization of the hind limb. Muscle atrophy is confirmed after a direct statistical comparison of the values of cross-sectional area (CSA) of muscle fibers studied in animals in groups I and C, sacrificed immediately after the immobilization period. Then the groups T3, T7, will undergo a rehabilitation program with muscle aerobic exercise (swimming) for 3 and 7 days respectively. Groups C, C3 and C7 are kept without stimulus atrophic and not be subjected to exercise. At the end of the experiment the animals are sacrificed and the soleus muscle removed. The quantitative analysis of gene expression of MyoD and myogenin will be performed by Real-Time Polymerase Chain Reaction after Reverse Transcription (RT-qPCR). Detection of proteins MyoD, myogenin and Pax-7, with counting of labeled nuclei will be analyzed by immunofluorescence. The data will be analyzed statistically. (AU)