The effect of treadmill training and N-acetyl-L-cysteine intervention on biogenesis of cytochrome c oxidase (COX)

Mitochondrial biogenesis refers to increased content of mitochondria, which has been shown to be promoted by aerobic exercise. During this process, oxidative stress is considered the essential initiator. Even though some studies have addressed the issue as to whether antioxidants would hamper the effects of exercise on mitochondrial biogenesis, no consensus has been achieved. Therefore, the purpose of the present study was to investigate the effects of exercise and antioxidant intervention on mitochondrial biogenesis, as well as COX biogenesis. Thirty-two clean-grade male ICR mice were randomly assigned to a control group (Con), exercise group (Ex), N-acetyl-L-cysteine group (NAC), or NAC plus exercise group (NEx). The NAC and NEx groups were injected with NAC (0.1 mg/g/2 days) intraperitoneally for 3 weeks, whereas the Con and Ex groups were administered saline for the same period of time. Mice assigned to Ex and NEx groups started exercise training 1 week before drug intervention was initiated. After 1 week of acclimatization, the mice were allowed to run at a speed of 28 m/min for 60 min, 6 days a week. The results showed that exercise training caused an increase in mRNA and protein levels of COXIV, whereas NAC intervention lowered the two so significantly that even exercise training could not reverse the effect of NAC intervention. Our data suggest that even though antioxidant intervention could alleviate oxidative damage caused by exercise, it was not necessarily beneficial for mitochondrial biogenesis.