Lack of dystrophin influences muscle inflammation but not myogenic regulatory factors after eccentric exercise in mdx mice

Aim: To investigate the consequences of chronic eccentric exercise in histopathology, inflammatory, and myogenic regulatory factors response in gastrocnemius muscle of X-chromosome-linked muscular dystrophy (mdx) mice. Method: Male mdx and control mice (C57BL/10 lineage) were distributed in the following groups: Sedentary Control (SC), Trained Control (TC), Sedentary Mdx (S-Mdx), and Trained Mdx (T-Mdx). Trained animals were subjected to downhill running for 7 weeks. Gastrocnemius was submitted to histopathological analysis and immunoexpression of Cyclooxygenase-2 (COX-2) and myogenic regulatory factors (myoD and myogenin). Results: The exercise influenced inflammation response as demonstrated by the increased COX-2 immunoexpression in T-Mdx. Interestingly, Myogenic regulatory factors revealed that the lack of dystrophin has not been influenced myoD and the increase of myogenin occurred due to exercise and was not aggravated by the absence of dystrophin. Conclusion: In conclusion, an eccentric exercise in gastrocnemius of mdx mice was characterized by an intense inflammatory process without myogenic response. These findings suggest that special attention should be given to inflammatory aspects related to COX-2 associated with a decrease of myoD expression, as biomarkers in motor rehabilitation programs.