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Arquivos de Neuro-Psiquiatria

Print version ISSN 0004-282X

Arq. Neuro-Psiquiatr. vol.47 no.2 São Paulo June 1989 

Alterações da junção neuromuscular em miopatias experimentais no camundongo


The neuromuscular junction in experimental myopathies in the mouse



Luiz Fernando Bleggi Torres

PhD, Professor Adjunto do Departamento de Patologia Médica, Hospital de Clínicas, Universidade Federal do Paraná




As alterações morfológicas observadas em junção neuromuscular de dois modelos de miopatia em camundongos são estudadas por métodos histoquímicos para demonstrar atividade da enzima acetilcolinesterase e por microscopia eletrônica. Em ambas as situações os resultados obtidos são similares, indicando que a junção neuromuscular permanece intacta mesmo quando a fibra que inerva está sofrendo necrose. Em fibras musculares regeneradas há acentuada simplificação das pregas pós-sinápticas, com redução de até 50% dos valores normais, comprovado por estudos morfométricos. A ausência de repercussões fisiológicas ou clínicas detectáveis nesses modelos, apesar da significativa hipotrofia da membrana pós-sináptica, sugere que a exuberante quantidade de pregas pós-sinápticas normalmente encontradas nas junções mioneürais pode representar mecanismo anatômico de segurança na transmissão química neuromuscular.


Morphological abnormalities of the neuromuscular junction in two murine models with primary myopathy were studied by combined cholinesterase-silver impregnation techniques and electron microscopy. In both situations the results were similar showing that the neuromuscular junction remained unaffected even when inervating necrotic muscle fibres. In regenerated muscle fibres, however, there was marked simplification of the post-synaptic membrane with reduction in number and depth of folds up to 50% of normal values confirmed by morphometric analysis. Since after regeneration succeded no detectable clinical or physiological alterations were observed in these experiments it seems reasonable to assume that the prominent branching of post-synaptic folds in normal skeletal muscles might represent an increased anatomical safety mechanism in chemical transmission.



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Agradecimentos - Este trabalho resulta de observações feitas durante Tese de PhD realizada no Departamento de Neuropatologia, Instituto de Neurologia, Universidade de Londres, Inglaterra, com apoio financeiro do CNPq. Agradecemos profundamente a supervisão do Prof. L.W. Duchen e, aos Drs. G. Brook e P. Gopalakrishnakone, por estudos colaborativos.



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