Duchenne muscular dystrophy (DMD) is a lethal X-linked recessive neuromuscular disorder caused by mutations in the dystrophin encoding gene, with the characteristics of a severe and progressive destruction of muscle s...Duchenne muscular dystrophy (DMD) is a lethal X-linked recessive neuromuscular disorder caused by mutations in the dystrophin encoding gene, with the characteristics of a severe and progressive destruction of muscle structure and function. Skeletal muscle fibrosis is one of the pathological features of DMD. Tetramethylpyrazine (2,3,5,6-tetramethylpyrazine, TMP) has been demonstrated to reduce heart and liver fibrosis. Meanwhile, previous studies showed that Tetramethylpyrazine nitrone (TBN), a nitrone derivative of TMP, has promising therapeutic effects in several neurodegenerative models and is more potent than TMP. In this study, we investigated the potential effect of TBN on the <em>mdx</em> mouse model of DMD. Eight-week-old <em>mdx</em> mice were administered with TBN (30 mg/kg) intragastrically twice daily, with deflazacort (1 mg/kg) once a day as a positive control, for a total of 24 weeks. Behavioral tests including pole-climbing open-field test were monitored every 4 weeks. Histopathological assessment was conducted in the gastrocnemius and diaphragm muscles. The effects of TBN on protein levels of dysferlin were measured by immunohistochemistry. TBN significantly reduced the climbing time in pole test and increased the total distance moved in an open-field test of <em>mdx</em> mice. TBN attenuated fibrosis in the gastrocnemius and diaphragmatic muscles. In addition, TBN protected gastrocnemius muscle fibers via increasing expression of the dysferlin in <em>mdx </em>mice. In conclusion, this study demonstrated that TBN could improve the motor deficits and muscle pathology of <em>mdx</em> mouse, and it is worth further exploring the mechanism of action of TBN for DMD treatment.展开更多
The mdx mouse is a model of Duchenne muscular dystrophy(DMD),a fatal progressive muscle wasting disease caused by dystrophin deficiency,and is used most widely in preclinical studies.Mice with dystrophin deficiency,ho...The mdx mouse is a model of Duchenne muscular dystrophy(DMD),a fatal progressive muscle wasting disease caused by dystrophin deficiency,and is used most widely in preclinical studies.Mice with dystrophin deficiency,however,show milder muscle strength phenotypes than humans.In human,the introduction of a sandwich enzyme-linked immunosorbent assay(ELISA)kit revealed a more than 700-fold increase in titin N-terminal fragment levels in the urine of pediatric patients with DMD.Notably,the urinary titin level declines with aging,reflecting progression of muscle wasting.In mouse,development of a highly sensitive ELISA kit has been awaited.Here,a sandwich ELISA kit to measure titin N-terminal fragment levels in mouse urine was developed.The developed kit showed good linearity,recovery,and repeatability in measuring recombinant or natural mouse titin N-terminal fragment levels.The titin N-terminal fragment concentration in the urine of mdx mice was more than 500-fold higher than that of normal mice.Urinary titin was further analyzed by extending the collection of urine samples to both young(3-11 weeks old)and aged(56-58 weeks old)mdx mice.The concentration in the young group was significantly higher than that in the aged group.It was concluded that muscle protein breakdown is active and persistent in mdx mice even though the muscle phenotype is mild.Our results provide an opportunity to develop DMD treatments that aim to alleviate muscle protein breakdown by monitoring urinary titin levels.展开更多
文摘Duchenne muscular dystrophy (DMD) is a lethal X-linked recessive neuromuscular disorder caused by mutations in the dystrophin encoding gene, with the characteristics of a severe and progressive destruction of muscle structure and function. Skeletal muscle fibrosis is one of the pathological features of DMD. Tetramethylpyrazine (2,3,5,6-tetramethylpyrazine, TMP) has been demonstrated to reduce heart and liver fibrosis. Meanwhile, previous studies showed that Tetramethylpyrazine nitrone (TBN), a nitrone derivative of TMP, has promising therapeutic effects in several neurodegenerative models and is more potent than TMP. In this study, we investigated the potential effect of TBN on the <em>mdx</em> mouse model of DMD. Eight-week-old <em>mdx</em> mice were administered with TBN (30 mg/kg) intragastrically twice daily, with deflazacort (1 mg/kg) once a day as a positive control, for a total of 24 weeks. Behavioral tests including pole-climbing open-field test were monitored every 4 weeks. Histopathological assessment was conducted in the gastrocnemius and diaphragm muscles. The effects of TBN on protein levels of dysferlin were measured by immunohistochemistry. TBN significantly reduced the climbing time in pole test and increased the total distance moved in an open-field test of <em>mdx</em> mice. TBN attenuated fibrosis in the gastrocnemius and diaphragmatic muscles. In addition, TBN protected gastrocnemius muscle fibers via increasing expression of the dysferlin in <em>mdx </em>mice. In conclusion, this study demonstrated that TBN could improve the motor deficits and muscle pathology of <em>mdx</em> mouse, and it is worth further exploring the mechanism of action of TBN for DMD treatment.
基金supported in part by the Practical Research Project for Rare/Intractable Diseases from the Japan Agency for Medical Research and Development (AMED20314714 to M.M.)
文摘The mdx mouse is a model of Duchenne muscular dystrophy(DMD),a fatal progressive muscle wasting disease caused by dystrophin deficiency,and is used most widely in preclinical studies.Mice with dystrophin deficiency,however,show milder muscle strength phenotypes than humans.In human,the introduction of a sandwich enzyme-linked immunosorbent assay(ELISA)kit revealed a more than 700-fold increase in titin N-terminal fragment levels in the urine of pediatric patients with DMD.Notably,the urinary titin level declines with aging,reflecting progression of muscle wasting.In mouse,development of a highly sensitive ELISA kit has been awaited.Here,a sandwich ELISA kit to measure titin N-terminal fragment levels in mouse urine was developed.The developed kit showed good linearity,recovery,and repeatability in measuring recombinant or natural mouse titin N-terminal fragment levels.The titin N-terminal fragment concentration in the urine of mdx mice was more than 500-fold higher than that of normal mice.Urinary titin was further analyzed by extending the collection of urine samples to both young(3-11 weeks old)and aged(56-58 weeks old)mdx mice.The concentration in the young group was significantly higher than that in the aged group.It was concluded that muscle protein breakdown is active and persistent in mdx mice even though the muscle phenotype is mild.Our results provide an opportunity to develop DMD treatments that aim to alleviate muscle protein breakdown by monitoring urinary titin levels.
