| Background:Decreased skeletal muscle mass and hypofunction due to age is known as myosis(sarcopenia),which is associated with protein degradation and increased oxidative stress in vivo and aging.The ubiquitin proteasome pathway is one of the main modes of protein degradation in vivo.in this pathway,there are two key skeletal muscle ubiquitin ligases E3,muscle atrophy Fbox protein(Atrogin-1)and muscle specific RING finger protein1(MuRF1).The study found that the IGF-1/Akt/FOXO pathway regulates the two E3 enzymes,and IGF-1 is the downstream target gene of miR-29 b which is significantly increased in many types of muscle atrophy,suggesting a certain regulatory effect on the pathway.studies have shown that exercise can improve protein degradation,and Lycium barbarum polysaccharide(LBP)can resist aging and reduce oxidative stress,but which type of exercise is more effective,and whether the combination of these two has a gain effect is rarely reported.Objective: To compare the effects of different exercise modes and Lycium barbarum polysaccharides(LBP)on skeletal muscle quality and related genes and protein expression in elderly and young mice,to explore the regulatory mechanisms of protein degradation pathway and miR-29 b in it,and to provide experimental basis for finding the best means of clinical adjuvant treatment for sarcopenia.Methods :Forty 15-month-old BALB/C female mice were randomly divided into elderly control group S,Lycium barbarum polysaccharide irrigation group G,treadmill running group E,treadmill running with stomach irrigation group EG,climbing ladder group R,climbing ladder with stomach irrigation group RG and Ten 3-months-old mice were young control group Y with six-week intervention.The skeletal muscle mass index(gastrocnemius weight/body weight)was measured.HE staining was used to observe the muscle fiber morphology,qPCR to detect the expression of miR-29 b and Atrogin-1 ? MuRF1 mRNA,Western blot to detect the expression of downstream protein and Atrogin-1?MuRF1.Results:(1)The skeletal muscle mass index(SMI)of the S group was significantly lower than that of the Y group(p?0.001)and five different intervention groups(G?EG?RG group(p?0.01)and E?R group(p?0.001)).Of the 5 intervention groups,E group was significantly higher than the other 4 groups(G?EG?RG group(p?0.01)and R group(p?0.05)).R group was significantly higher than RG group(p?0.05).(2)In S group,the intranuclear migration of muscle fibers increased significantly,and along with the uneven size and morphology of cells,the spacing of muscle fibers increased,and the atrophy of muscle fibers became obvious.the cross-sectional area of muscle fibers in S group was significantly smaller than that in Y group(p?0.001)and in each intervention group(G group(p?0.05)and E?EG?R?RG group(p?0.001)).G group was significantly lower than E?R group(p?0.001).(3)The expression of miR-29 b in the S group was significantly higher than that in the Y?E group(p?0.05).R group was significantly higher than G(p?0.05),RG(p?0.01)and E?EG(p?0.001).the expression of Atrogin-1mRNA in the S group was significantly lower than that in the other groups(Y?G?EG?R(p?0.001),RG(p?0.01))except E.G group was significantly lower than R group(p?0.01).E group was significantly lower than the other three intervention groups(G?EG?R(p?0.001)and RG(p?0.01)).The expression of MuRF1 mRNA in the S group was significantly lower than other groups except the E group(p?0.001)and significantly higher than E(p?0.001).E group was significantly lower than G?EG?R?RG group(p?0.001).EG?R group was significantly lower than RG group(p?0.001).(4)The degree of Akt phosphorylation in S group was significantly higher than that in Y group and other five intervention groups except G group(p?0.05).The degree of FOXO1 phosphorylation in S group was significantly lower than Y(p?0.001)?E(p?0.01)?EG(p?0.05),higher than R(p?0.05).E group was significantly higher than R group(p?0.001)and RG group(p?0.05),EG group was significantly higher than R group(p?0.01).Atrogin-1 protein expression was significantly higher in S group than in Y?R?RG group(p?0.001)and in G?EG group(p?0.05).E group was significantly higher than G group(p?0.05)?EG group(p?0.01)and R?RG group(p?0.001).EG group was significantly higher than R(p?0.001)and RG(p?0.05).R group was significantly lower than EG?RG group(p?0.001)?G group(p?0.05).MuRF1 protein expression was significantly higher in the S group than in the Y group(p?0.001)and in the intervention groups(G group(p?0.05)andE?EG?R?RG group(p?0.01)).G group was significantly higher than E(p?0.01)and R(p?0.05).There was no significant difference between E?EG?R?RG group.(5)The correlation analysis among the indexes showed that the cross-sectional area of muscle fiber was moderately negatively correlated with miR-29b(r=-0.46),Atrogin-1 protein expression(r=-0.57),strongly negatively correlated with MuRF1 protein expression(r=-0.62)and strongly positively correlated with FOXO1 phosphorylation(0.63).the degree of FOXO1 phosphorylation was moderately negatively correlated with Atrogin-1 protein expression(r=-0.54)and strongly negatively correlated with miR-29 b expression(r=-0.65).MuRF1 mRNA expression was moderately negatively correlated with MuRF1 protein expression(r=-0.46)and very strongly correlated with Atrogin-1mRNA expression(0.95).Conclusions:(1)After 6 weeks of intervention,whether it was running platform,climbing ladder movement or Lycium barbarum polysaccharide(LBP)gavage,the skeletal muscle mass index and cross-sectional area of aging mice were significantly increased,and the running platform was similar to the climbing ladder effect,indicating that aerobic exercise and resistance exercise can be used to improve sarcopenia.(2)The effect of resistance or resistance combined with Lycium barbarum polysaccharide on Atrogin-1 protein was more obvious,and different exercise intervention on MuRF1 protein was better than that of single Lycium barbarum polysaccharide,so the effect of exercise on sarcopenia related protein was generally better than that of Lycium barbarum polysaccharide,but the combination of the two intervention methods had no obvious active effects.(3)The increases of miR-29b?Atrogin-1 and MuRF1 protein expression could be used as markers of sarcopenia occurrence. |
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