Experimental study of alendronate sodium in the treatment of denervated skeletal muscle atrophy / 中华骨科杂志

ABSTRACT

Objective:To observe the effects of alendronate (ALN) on the expression of autophagy signaling pathway related proteins LC3, Beclin-1 and P62 in the muscle tissue of mice with denervated skeletal muscle atrophy, and to explore the potential molecular biological mechanism of ALN in the treatment of skeletal muscle atrophy.Methods:Thirty males C57BL/6 mice were divided into three groups with 10 mices in each group by random number method, including blank control group sciatic nerve exposed without resection, model group sciatic nerve exposed and resection, ALN group sciatic nerve resection +ALN intervention. At the intervention stage, mices were given 1 mg/kg ALN by intragastric administration. The weight of gastrocnemius muscle was weighed by wet weight method. Atpase staining was used to distinguish muscle fiber types. HE staining was used to observe the arrangement and cross-sectional area of gastrocnemius muscle fibers in each group, and further quantitative analysis was performed by Image J 1.48 software. Western blotting and immunohistochemical staining were performed to detect the expressions of MHC and MuRF1 as well as LC3, Beclin-1 and P62 in gastrocnemius tissues of each group.Results:The weight of gastrocnemius muscle in the model group 137±7.80 mg was significantly lower than that in the blank control group 203±10.34 mg, which proved that the denervation muscle atrophy mouse model was successfully established. After intervention, the gastrocnemius muscle weight of ALN group 177±11.65 mg was significantly higher than that of model group, and the muscle mass was significantly improved. HE staining showed that muscle fibers in the model group were loosely arranged and the cross-sectional area was significantly smaller than that in the blank control group, and there were more blue stains among muscle fibers. Atpase staining showed that the distribution of type II muscle fibers in the model group was increased compared with that in the blank control group, and the distribution of type II muscle fibers in the ALN group was decreased compared with that in the model group, but higher than that in the blank control group. The results showed that the most widely distributed muscle fiber cross-sectional area was 600-800μm 2 in the blank control group, 200-400 μm 2 in the model group, and 400-600 μm 2 in the ALN group. The results of quantitative calculation of muscle fiber cross-sectional area by Image J 1.48 showed that the mean value of muscle fiber cross-sectional area in the model group was (352±18) μm 2, which was significantly reduced compared with the blank control group 794±20 μm 2. After ALN treatment, muscle fiber cross-sectional area recovered somewhat. The mean muscle fiber cross-sectional area of ALN group was 578±23 μm 2, which increased muscle fiber cross-sectional area by 29%. Western blotting results showed that the expressions of MHC, LC3 and Beclin-1 in model group were significantly lower than those in blank control group ( P<0.05), while MuRF1 and P62 proteins were significantly higher than those in blank control group ( P<0.05). The MHC, LC3 and Beclin-1 proteins in ALN group were significantly higher than those in model group (0.12±0.01 vs. 0.10±0.003, 0.15±0.02 vs. 0.10±0.02, 0.13±0.03 vs. 0.09±0.04). MuRF1 and P62 proteins in ALN group were significantly lower than those in model group (0.10±0.004 vs. 0.15±0.01, 0.16±0.03 vs. 0.20±0.03). MHC immunohistochemical staining showed that the expression of MHC in gastrocnemius of mice in model group was significantly lower than that in blank control group, and the expression of MHC in gastrocnemius of mice in ALN group was higher than that in model group ( P<0.05). Conclusion:ALN has a therapeutic effect on skeletal muscle atrophy, and its mechanism may be realized by moderately activating the LC3/Beclin-1 autophagy signaling pathway.