Orientador: Maria Julia Marques / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-11T07:52:24Z (GMT). No. of bitstreams: 1
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Previous issue date: 2008 / Resumo: A ausência da distrofina em fibras musculares de camundongos mdx e na Distrofia Muscular de Duchenne (DMD) provoca ruptura no sarcolema, aumento no influxo de cálcio e conseqüente degeneração muscular. Neste trabalho verificamos os efeitos dos bloqueadores de canais de cálcio diltiazem e verapamil na degeneração/regeneração do músculo distrófico de camundongos mdx. Camundongos mdx (n=32; 18 dias de vida pós-natal) receberam diariamente injeção intraperitoneal de diltiazem (n=16; 72 mg/kg) ou verapamil (n=16; 25 mg/kg) por 18 dias. Após este período os músculos esternomastóide, diafragma, tibial anterior e coração foram retirados. Animais mdx controle (n=16) foram injetados com solução salina. Ambas drogas diminuíram significativamente os níveis séricos de creatina quinase (mdx tratado com salina: 573±245 U/l, animais tratado com diltiazem: 161±53*U/l e animais tratados com verapamil: 217±57*U/l; média±desvio padrão, *p<0,05 comparados a animais tratados com salina, teste t de Student). A quantificação de cálcio total, por espectrômetro de emissão óptica em plasma, foi 173-475% maior em músculos do mdx comparado a músculos de animais controles não-distróficos C57Bl/10. Verapamil e diltiazem reduziram a concentração de cálcio total apenas no diafragma (diltiazem: 229 mg de cálcio/kg versus salina: 295mg de cálcio/kg; p=0,06, teste t de Student) e no músculo cardíaco (diltiazem/verapamil: 10 mg de cálcio/kg versus salina: 16 mg de cálcio/kg; p<0,05, teste t de Student). Na análise histológica, o diltiazem diminui significativamente a degeneração muscular no diafragma (salina: 28% fibras com núcleo central e 7% fibras positivas ao Azul de Evans versus 12% fibras com núcleo central e 1% fibras positivas ao Azul de Evans; p<0,05, teste t de Student). Encontramos um aumento significativo de calsequestrina e ß-distroglicana, pela técnica de Western blotting, em alguns músculos dos animais tratados com diltiazem e verapamil. O diltiazem aparenta ser o mais efetivo agente na proteção contra degeneração muscular, especialmente nos músculos mais afetados. Nossos resultados indicam que bloqueadores de canais de cálcio protegem contra a degeneração muscular na ausência de distrofina e podem ser úteis para o melhor entendimento dos mecanismos envolvidos nas distrofinopatias / Abstract: The lack of dystrophin in dystrophin-deficient fibers of mdx mice and in Duchenne muscular dystrophy leads to sarcolemmal breakdown and enhanced calcium influx followed by muscle degeneration.In this work, we examined whether the calcium channel blockers diltiazem and verapamil could protect dystrophic muscles from degeneration/regeneration. Mdx mice (n=32; 18 days old) received daily intraperitoneal injections of diltiazem (n=16; 72 mg/kg body weight) or verapamil (n=16; 25 mg/kg body weight) for 18 days, after which the sternomastoid, diaphragm, tibialis anterior and cardiac muscles were removed. Control mdx mice (n=16) were injected with saline. Both drugs significantly decreased the blood levels of creatine kinase (saline-treated mdx mice: 573±245 U/l, diltiazem-treated mice: 161±53* U/l and verapamil-treated mice: 217±57* U/l; mean+S.E.M., *p<0.05 vs. saline controls, Student's t-test). The total calcium content, measured by plasma emission spectrometry, was 173-475% greater in mdx muscles compared to control C57Bl/10 muscles. Verapamil and diltiazem reduced the total calcium content only in diaphragm (diltiazem-treated mice: 229 mg calcium/kg vs. saline-treated mice: 295 mg calcium/kg; p=0.06, Student¿s t-test) and cardiac muscle (diltiazem/verapamil-treated mice: 10 mg calcium/kg vs. saline-treated mice: 16 mg calcium/kg; p<0.05, Student¿s t-test). Histological analysis showed that diltiazem significantly attenuated muscle degeneration only in diaphragm muscle (28% central nucleated fibers and 7% Evans blue-positive fibers in saline-treated mice vs. 12% central nucleated fibers and 1% Evans blue-positive fibers in diltiazem-treated mice; p<0.05, Student¿s t-test). Immunoblots showed a significant increase in the levels of calsequestrin and ß-dystroglycan in some diltiazem- and verapamil-treated muscles. Diltiazem was more effective than verapamil in protecting against muscle degeneration in mdx mice, especially in the more affected muscles. These results indicate that calcium channel blockers protect against muscle degeneration in the absence of dystrophin. They also suggest that these drugs could be useful therapeutic alternatives in the treatment of Duchenne muscular dystrophy. ABSTRACT The lack of dystrophin in dystrophin-deficient fibers of mdx mice and in Duchenne muscular dystrophy leads to sarcolemmal breakdown and enhanced calcium influx followed by muscle degeneration.In this work, we examined whether the calcium channel blockers diltiazem and verapamil could protect dystrophic muscles from degeneration/regeneration. Mdx mice (n=32; 18 days old) received daily intraperitoneal injections of diltiazem (n=16; 72 mg/kg body weight) or verapamil (n=16; 25 mg/kg body weight) for 18 days, after which the sternomastoid, diaphragm, tibialis anterior and cardiac muscles were removed. Control mdx mice (n=16) were injected with saline. Both drugs significantly decreased the blood levels of creatine kinase (saline-treated mdx mice: 573±245 U/l, diltiazem-treated mice: 161±53* U/l and verapamil-treated mice: 217±57* U/l; mean+S.E.M., *p<0.05 vs. saline controls, Student's t-test). The total calcium content, measured by plasma emission spectrometry, was 173-475% greater in mdx muscles compared to control C57Bl/10 muscles. Verapamil and diltiazem reduced the total calcium content only in diaphragm (diltiazem-treated mice: 229 mg calcium/kg vs. saline-treated mice: 295 mg calcium/kg; p=0.06, Student¿s t-test) and cardiac muscle (diltiazem/verapamil-treated mice: 10 mg calcium/kg vs. saline-treated mice: 16 mg calcium/kg; p<0.05, Student¿s t-test). Histological analysis showed that diltiazem significantly attenuated muscle degeneration only in diaphragm muscle (28% central nucleated fibers and 7% Evans blue-positive fibers in saline-treated mice vs. 12% central nucleated fibers and 1% Evans blue-positive fibers in diltiazem-treated mice; p<0.05, Student¿s t-test). Immunoblots showed a significant increase in the levels of calsequestrin and ß-dystroglycan in some diltiazem- and verapamil-treated muscles. Diltiazem was more effective than verapamil in protecting against muscle degeneration in mdx mice, especially in the more affected muscles. These results indicate that calcium channel blockers protect against muscle degeneration in the absence of dystrophin. They also suggest that these drugs could be useful therapeutic alternatives in the treatment of Duchenne muscular dystrophy / Mestrado / Biologia Celular / Mestre em Biologia Celular e Estrutural
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.unicamp.br:REPOSIP/317770 |
| Date | 06 February 2008 |
| Creators | Matsumura, Cintia Yuri, 1981- |
| Contributors | UNIVERSIDADE ESTADUAL DE CAMPINAS, Marques, Maria Julia, 1961-, Garcia, Luis Alonso, Silva, Maeli Dal Pai |
| Publisher | [s.n.], Universidade Estadual de Campinas. Instituto de Biologia, Programa de Pós-Graduação em Biologia Celular e Estrutural |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | 87f. : il., application/pdf |
| Source | reponame:Repositório Institucional da Unicamp, instname:Universidade Estadual de Campinas, instacron:UNICAMP |
| Rights | info:eu-repo/semantics/openAccess |
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