To explore the combined effects of exercise and melatonin supplement against the challenges of isoproterenol-induced cardiac oxidative stress and injury in rats., the expression of peroxisome proliferator-activated receptor gamma co-activator-1α (PGC-1α), mitochondrial biogenesis, and adenosine triphosphate (ATP) was up-regulated in cardiac muscle in normal rats and in a melatonin and exercise regimented group. Cardiac injury was induced by two subcutaneous injections of isoproterenol in the rats. The combination of exercise and melatonin supplement successfully counteracted the isoproterenol-induced cardiac injury, which is reflected by the improved hemodynamic parameters, reduction in oxidative stress markers, and cardiac injury serum markers (cardiac troponin-I and creatine kinase-MB). The cardiac tissue level of ATP, expression of PGC-1α and mitochondrial biogenesis-related genes, mitochondrial membrane potential, and the activities of typical antioxidants (glutathione, superoxide dismutase) were preserved, whereas the levels of reactive oxygen species, lipid peroxidation, and inflammatory cytokines were suppressed in the melatonin and exercise regimented (MEI) group compared to the group treated with isoproterenol alone. Furthermore, the expression of endoplasmic reticular stress- and apoptosis-related proteins (Bax, Bcl2, and caspase-3) was also effectively suppressed in the MEI group. Therefore, the present study suggests that melatonin supplement in combination with exercise prevents cardiac injury, possibly through the preservation of mitochondrial function and inhibition of oxidative stress in rats.
Keywords: antioxidant; cardiac injury; exercise; isoproterenol; melatonin; oxidative stress.