Exercise induces mitochondrial biogenesis after brain ischemia in rats

Stroke is a major cause of death worldwide. Previous studies have suggested both exercise and mitochondrial biogenesis contribute to improved post-ischemic recovery of brain function. However, the exact mechanism underlying this effect is unclear. On the other hand, the benefit of exercise-induced mitochondrial biogenesis in brain has been confirmed. In this study, we attempted to determine whether treadmill exercise induces functional improvement through regulation of mitochondrial biogenesis after brain ischemia. We subjected adult male rats to ischemia, followed by either treadmill exercise or non-exercise and analyzed the effect of exercise on the amount of mitochondrial DNA (mtDNA), expression of mitochondrial biogenesis factors, and mitochondrial protein. In the ischemia-exercise group, only peroxisome proliferator activated receptor coactivator-1 (PGC-1) expression was increased significantly after 3 days of treadmill training. However, after 7 days of training, the levels of mtDNA, nuclear respiratory factor 1, NRF-1, mitochondrial transcription factor A, TFAM, and the mitochondrial protein cytochrome C oxidase subunit IV (COXIV) and heat shock protein-60 (HSP60) also increased above levels observed in non-exercised ischemic animals. These changes followed with significant changes in behavioral scores and cerebral infarct volume. The results indicate that exercise can promote mitochondrial biogenesis after ischemic injury, which may serve as a novel component of exercise-induced repair mechanisms of the brain. Understanding the molecular basis for exercise-induced neuroprotection may be beneficial in the development of therapeutic approaches for brain recovery from the ischemic injury. Based upon our findings, stimulation or enhancement of mitochondrial biogenesis may prove a novel neuroprotective strategy in the future.