Effects Of Different Duration Endurance Exercise On Expression Of Foxo3,mafbx32 And Murf1 In Soleus Of Old Mice

OBJECTIVE: To investigate the effects of different durations running on expression of regulatory proteins FOXO3α, MAFbx32 and MuRF1 in soleus of old mice, which could provide a promising way to improve sarcopenia with aging. METHODS: 32 mice of 11-month were randomly divided into 4groups: 4-week control group (4C), 4-week exercise group (4 T), 8-week quiet group (8C) and 8-week exercise group(8 T). Groups 4C and 8C were the control groups, and 4 T and 8 T groups had endurance running with a speed of 15 m/min on running platform. In the 4C group and the 4 T group, the soleus were sampled 24 hours after the end of the last training of the 4 T group, and the 8C group and the 8 T group were treated in the same way. The body weight and the soleus weight were measured. The CSA of the soleus fibers were observed. The regulatory proteins FOXO3α, MAFbx32 and MuRF1 were detected by western blotting. The study was approved by the ethic committee of Beijing Sport University. RESULTS: 1. The wet soleus–body weight ratio. Compared with 4C’s (0.26 ± 0.04), 4 T (0.31 ± 0.05), 8C (0.28 ± 0.03) and 8 T (0.29 ± 0.04), the ratio of 4 T group was higher than 4C’s (P < 0.05). 2. Cross sectional area of soleus: Compared with 4C (2095.7 ± 225.6), the CSA in 4 T (2593.3 ± 49.1) increased by 23.7. % (P < 0.01).The 8C’s (1921.4 ± 226.7) were lower by 17.4% compared with the 8 T’s (P < 0.01). 3. Soleus regulatory proteins: FOXO3α: Compared with 4C (0.44 ± 0.26), 4 T (0.38 ± 0.2) and 8 T (0.43 ± 0.15) showed a downward trend after intervention. The 8C (0.46 ± 0.06) was higher compared with the 4C. MAFbx32: The 8C (0.44 ± 0.07) was significantly higher than the 4C(0.28 ± 0.08) (P < 0.01). The 8 T (0.28 ± 0.11) were significantly lower than the 8C’s (P < 0.01). MuRF1: Compared with 4C (0.32 ± 0.16), 4 T (0.29 ± 0.1) and 8 T (0.3 ± 0.12) showed a decreasing trend after intervention(P > 0.05). The 8C’s (0.39 ± 0.20) was higher than that of the 4C. CONCLUSION: 1.Endurance running with 4 weeks or 8 weeks benefited delaying sarcopenia with aging and 4-week exercise displayed obvious effect. 2. The mechanism of endurance exercise to delay the development of sarcopenia could be that endurance exercise decreased FOXO3α expression, and in turn to inhibit the expression of MAFbx32 and MuRF1, which reduced the degradation of soleus.