Metformin Increases Sarcolemma Integrity And Ameliorates Neuromuscular Deficits In A Murine Model Of Duchenne Muscular Dystrophy

Duchenne muscular dystrophy(DMD)is a genetic neuromuscular disease characterized by progressive muscle weakness and wasting.Stimulation of AMPactivated protein kinase(AMPK)has been demonstrated to increase muscle function and protect muscle against damage in dystrophic mice.Metformin is a widely used antihyperglycemic drug,at the same time,studies have shown that it can indirectly activate AMPK and is used as an indirect activator of AMPK.Based on these findings,we hypothesized that metformin has a therapeutic effect on the neuromuscular deficits of DMD disease.In this study,the widely used mdx mice were used as DMD model mice,and metformin was continuously injected into the mdx mice every day to test the therapeutic effect of metformin on DMD.We found that the injection of metformin increased muscle strength accompanied by elevated twitch and tetanic force of tibialis anterior(TA)muscle in mdx mice.Immunofluorescence and electron microscopy analysis of metformin-treated mdx muscles revealed an improvement in muscle fiber membrane integrity.Electrophysiological studies showed the amplitude of miniature endplate potentials(mEPP)was increased in treated mice,indicating metformin also improved neuromuscular synapse transmission of the mdx mice.Using qRT-PCR and Wertern blot technology to analysis the mRNA and protein levels from muscles of treated mice showed an upregulation of AMPK phosphorylation and dystrophicglycoprotein complex protein expression.Based on the above results,we conclude that metformin can indeed improve muscle function and diminish neuromuscular deficits in mdx mice,suggesting its potential use as a therapeutic drug in DMD patients.Our results will provide an important clue for the diagnosis and treatment of DMD disease,and provide a theoretical basis for the pathological molecular mechanism of DMD.