Abstract
Purpose
Loss of skeletal muscle mass, which depends on a balance between protein synthesis and degradation, is common in sarcopenia, cachexia, and some diseases. The purpose of this study was to investigate the alterations and interactions of protein synthesis and degradation signaling components induced by 8-week endurance exercise training with a normal diet.
Methods
Two exercise (
n
= 8) and control (
n
= 7) groups of Wistar rats were kept under standard conditions. The exercise group performed 8-week endurance running at 65–70% VO2max, 30–60 min, on a treadmill with 0° slope, and the rats of the control group were maintained under identical conditions except exercise training. Forty-eight hours after the last exercise session, the dissected soleus muscles were stored at − 80 °C for gene and protein expression analyses.
Results
Although there was a non-significant increase in mTOR gene expression, Akt1 and S6K1 increased significantly compared with the control group, which was confirmed by Western blot analysis. In addition, given that the FoxO3a did not increase, 4E-BP1 and LC3a were suppressed significantly and were confirmed by Western blot analysis. Contrary to our hypothesis, the MuRF1 gene expression was significantly increased compared with the control group.
Conclusion
The results showed that the moderate-intensity endurance exercise training protocol with no calories restrictions, normal diet, not only does not lead to protein degradation but also sufficiently activates protein synthesis signaling. Further investigations including exercise training with different intensities and nutritional status are needed to reveal the cause of the unusual MuRF1 response.