Melatonin decreases PAX7 and CK increment after exercise-induced skeletal muscle damage

Introduction Exercise-induced muscle damage (EIMD) triggers several events that will initiate the repair process of this tissue through the activation of satellite cells (SC). The transcription factor PAX7 is used as a SC marker, being expressed during the quiescence, activation, and proliferation of these cells. The literature presents some therapeutic resources aimed at reducing damage or accelerating the muscle repair, acting on inflammation or oxidative stress. Among such therapeutic resources, we can find the melatonin administration, a hormone with anti-inflammatory, antiapoptotic, and antioxidant actions. Purpose This study aims to analyze the effects of melatonin on PAX7 after EIMD. Methods Sixty-five male Wistar rats were divided into seven groups: control (CTG), which received vehicle solution (ethanol and NaCl) and were euthanized at 98 days old, and six groups that received melatonin (EMG) or not (EG) immediately after the skeletal muscle damage induction protocol (SMDIP) through swimming exercise, being euthanized 24, 48, or 72 h after the SMDIP, denominated EG24, EG48, EG72, EMG24, EMG48, and EMG72. Results There was an effect of time showing higher serum creatine kinase 48 h after SMDIP (F = 3.27; p < 0.05) compared to 24 or 72 h after. However, the group EMG48 showed a significant reduction (p = 0.010) in the concentration of this enzyme in relation to EG48. There was a reduction in PAX7 in animals that received melatonin in comparison with those that received vehicle solution (F = 13.90; p = 0.001). Conclusion Melatonin reduced muscle damage, demonstrated by the decrease of CK-MM and PAX7.