Efeitos do exercício aeróbio de baixa intensidade e da melatonina nos músculos esquelético e cardíaco de camundongos mdx ; Effects of low-intensity aerobic exercise and melatonin on skeletal and cardiac muscles of mdx mice

Duchenne Muscular Dystrophy (DMD), affecting 1 in every 5,000 live births, affects the X chromosome, responsible for the synthesis of the dystrophin protein that maintains the stability of the cell membrane, making it resistant to mechanical forces. It causes ruptures, necrosis, and increased serum levels of cytoplasmic enzymes, which activate proteases, stimulating the degeneration of muscle fibers. The diagnosis is made through clinical examinations such as: muscle biopsy, Creatine Kinase (CK), and DNA measurement. Due to recurrent injuries, satellite cells are constantly activated to carry out the tissue repair process. In this way, these cells end up entering an exhaustion process, reducing the “pool” of quiescent cells, and affecting the regenerative process. Physical exercise is an important and low-cost therapy that has been explored in the rehabilitation of patients with DMD. Studies show that a lack of physical activity can determine changes in the functionality of the muscular, cardiac, and respiratory systems. Experimental studies with mdx mice have shown that low-intensity physical exercise increases the expression of CS, muscle mass, and strength and improves tissue cytoarchitecture. In parallel to therapies through physical exercise, DMD is also targeted by drugs. The most common of these is cortisol, a drug that is capable of significantly reducing the degenerative process of muscle fibers, but, on the other hand, causes side effects. Currently, melatonin has become the focus of research in the process of muscle regeneration after injury. Melatonin has several functions in the body, in addition to antioxidant and anti-inflammatory actions. Aiming at antioxidant and anti-inflammatory power, studies have shown that patients with DMD have increased expression of anti-inflammatory cytokines and these same authors have found a significant reduction in muscle necrosis markers. Exogenous administration of melatonin has been shown to increase the number of satellite cells and improve the strength and ...