The Effect of Uphill and Downhill Exercise Training on Myogenic Mechanism of Wnt/BMP Signaling in the Skeletal Muscle of Aged Rats

Abstract

PURPOSE The purpose of this study was to determine the effect of exercise types on the Wnt/BMP signaling and the response to myogenic mechanism by downhill and uphill training in the aged rat skeletal muscles. METHODS Young and old rats were randomly assigned to control groups; young (YC) and old (OC), and two types of running training groups: old downhill exercise (ODE) and old uphill exercise (OUE). Training was progressively carried out on a treadmill at a speed of 21 m/min with a slope of +10° for uphill training vs 16 m/min with a slope of -16° for downhill training: 60 min/day, 5 days/week for 8 weeks respectively. RESULTS Downhill and uphill training significantly increased the protein levels of Wnt3a, β-catenin and LEF-1 in aged rats. On the contrary, GSK3β was reduced by running training. In addition, the expression patterns of Wnt7a, Fzd7, PKC, p-AKT, and p-mTOR in extensor digitorum longus (EDL) and soleus (SOL) muscle were significantly increased in both ODE and OUE groups. Expression patterns of BMP-2, BMP-7, and p-Smad-1/5/8 in EDL and SOL muscles were significantly increased in both ODE and OUE groups. Especially, ODE group showed more increased expression pattern than OUE group. The expression patterns of MyoD, Myf5, and Myogenin were significantly increased in both DOE and OUE groups. Myf5 and Myogenin showed more increased expression pattern in ODE group than OUE group. CONCLUSIONS The downhill and uphill exercise training may play a mediating role in increasing the expression of these reduced myogenesis related factors. Furthermore, the formation process and hypertrophy of skeletal muscle weakened due to aging can be improved and maintained.

Keywords

• aged muscles
• downhill and uphill exercise
• gsk3β
• bmp-2
• bmp-7