Alterações da junção neuromuscular em miopatias experimentais no camundongo

Torres, Luiz Fernando Bleggi

doi:10.1590/S0004-282X1989000200001

Resumos

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.

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

RESUMO

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.

SUMMARY

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.

Departamento de Patologia Médica, Hospital de Clínicas - Rua General Carneiro 181 - 80069 Curitiba PR - Brasil.

1. Banker BQ, Kelly SS, Robbins N - Neuromuscular transmission and correlative morphology in young and old mice. J Physiol 339:355, 1983.
2. Banker BQ, Hirst NS, Chester CS, Fok RY - Histometric and electron cytochemical study of muscle in the dystrophic mouse. Ann New York Acad Sci 317:374, 1979.
3. Beam KG, Caldwell JH, Campbell DT - Na channels in skeletal muscle concentrated near the neuromuscular junction. Nature 313:588, 1985.
4. Betz W, Sakmann B - Effects of proteolytic enzymes on function and structure of frog neuromuscular junctions. J Physiol 230:673, 1973.
5. Blaxter KL - Myopathies in animals. In Walton J: Disorders of Voluntary Muscle. Churchill Livingstone, Edinburgh, 1974.
6. Bowden, REM, Duche LW - The anatomy and pathology of the neuromuscular junction. In Zaimis E: Handbook of Experimental Pharmacology. Springer, Berlin, 1976.
7. Bradley R, Fell BF - Myopathies in animals. In Walton J: Disorders of Voluntary Muscle. Churchill Livingstone, Edinburgh, 1981.
8. Brook G, Torres LF, Gopalakrishnakone P, Duchen LW - Effects of phospholipase of Enhydrina schistosa venom on nerve, motor end-plate and muscle of the mouse. Quart J Experi Physiol 72:571, 1987.
9. Buchthal F, Schmalbruch H - Motor unit of mammalian muscle. Physiol Rev 60:90, 1980.
10. Coers C - Morphologie de la jonction neuro-musculaire. Arch Biol (Liege) 75 (suppl): 905, 1964.
11. Couteaux R - Morphological and cytochemical observations on the post-synaptic membrane at motor end-plates and ganglionic synapses. Exper Cell Res 5 (suppl):294, 1958.
12. Duchen LW - An electron microscopic comparison of motor end-plates of slow and fast skeletal muscle fibres of the mouse. J Neurol Sci 14:37, 1970.
13. Duchen LW, Excell BJ, Patel R, Smith B - Changes in motor end-plates resulting from muscle fibre necrosis and regeneration: a light and electron microscopic study of the effects of the depolarizing fraction of Dendroaspis jamesoni venom. J Neurol Sci 21:391, 1974.
14. Ellisman MH - The membrane morphology of the neuromuscular junction, sarcolemma, sarcoplasmic reticulum and transverse tubule system in murine muscular dystrophy studied by freeze-fracture electron microscopy. Brain Res 214:261, 1981.
15. Engel AG, Santa T - Histometric analysis of the ultrastructure of the neuromuscular junction in myasthenia gravis and in the myasthenic syndrome. Ann New York Acad Sci 183: 46, 1971.
16. Engel AG, Jerusalem F, Tsujihata M, Gomez MR - The neuromuscular junction in myopathies: a quantitative ultrastructural study. Recent Advances in Myology 360:132, 1974.
17. Fahim MA, Robbins N - Ultrastructure studies of young and old mouse neuromuscular junctions. J Neurocytol 11:641, 1982.
18. Fardeau M - Ultrastruture des jonctions neuromusculaires dans la musculature sque-_ lettique du cobaye. In Israel M, Manaranche R: La Transmission Cholinergique de L'Excitation. Inserm, Paris, 1973.
19. Grinnell AD, Herrera AA - Specificity and plasticity of neuromuscular connections: long-term regulation of motor neuron function. Progress in Neurobiol 17:203, 1981.
20. Gwyn DG, Aitken JT - The formation of new end-plates in mammalian skeletal muscle. J Anatomy 100: 116, 1966.
21. Harriman DGF - A comparision of the fine structure of motor end-plates in Duchenne dystrophy and in human neurogenic diseases. J Neurol Sci 28:233, 1976.
22. Hopkins WG, Brown MC, Keynes RJ - Postnatal growth of motor nerve terminals in muscles of the mouse. J Neurocyt 14:525, 1985.
23. Jirmanova I - Ultrastructure of motor end-plates during pharmacologically induced degeneration and subsequent regeneration of skeletal muscle. J Neurocytol 4:141, 1975.
24. Kakulas BA - Experimental Myopathies. In Walton J: Disorders of Voluntary Muscle. Churchill Livingstone, Edinburgh, 1981.
25. Kakulas BA - Toxic and drug-induced myopathies. In Mastaglia FL, Walton J: Skeletal Muscle Pathology. Churchill Livingstone, Edinburgh, 1982.
26. Karnovsky MJ - A formaldehyde-gluraraldehyde fixative of high osmolarity for use in electron microscopy. J Cell Biol 27:137A, 1965.
27. Koenig J - Morphogenesis of motor end-plates 'in vivo' and 'in vitro'. Brain Res 62:361, 1973.
28. Law PK, Saito A, Fleischer S - Ultrastructural changes in muscle and motor end-plate of the dystrophic mouse. Exper Neurol 80:361, 1983.
29. McMahan UJ, Edgington DR, Kuffler DP - Factor that influence regeneration of the neuromuscular junction. J Exper Biol 89:31, 1980.
30. Namba T, Nakamura T, Grob D - Staining for nerve fibre and cholinesterase activity in fresh frozen sections. Am J Clin Pathol 47:74, 1967.
31. Ontell M, Haller E - Necrotic extrafusal muscle fibres of the dystrophic mutant mouse: the ultrastructure of the myoneural junction. Anat Rec 197:397, 1980.
32. Padykula HA, Gauthier GF - The ultrastructure of the neuromuscular junction of mammalian red, wthite and intermediate skeletal muscle fibres. J Cell Biol 46:27, 1970.
33. Pestronk A, Drachman D - A new stain for quantitative measurement of sprouting at neuromuscular junctions. Muscle and Nerve, 1:70, 1978.
34. Queiroz LS - Effects of neurotoxins on muscle and nerve in the mouse: morphological and physiological studies. Tese PhD. Universidade de Londres, Inglaterra, 1981.
35. Santa T, Engel AG - Histometric analysis of neuromuscular junction ultrastructure in rat red, white and intermediate muscle fibres. In Desmedt JE: New Developments in EMG and Clinical Neurophysiology. Karger, Basel, 1973.
36. Snell RS, Mclntyre N - Effect of denervation on the histochemical appearance of cholinesterase at the myoneural junction. Nature 176:884, 1955.
37. Snell RS, Mclntyre N - Changes in the histochemical appearances of cholinesterase at the motor end-plate following denervation. Br J Exper Pathol 37 (1), 1956.
38. Telford IR, Einarson L - Experimental muscular dystrophies in animals. Charles Thomas, USA, 1971.
39. Torres LFB - Muscle, motor end-plate and nerves in hereditary and experimental myopathies in the mouse. Tese PhD. Universidade de Londres, Inglaterra, 1986.
40. Torres LFB - Inherited neuromuscular diseases in the mouse: a review of the literature. Arq Neuro-Psiquiat (São Paulo) 46:298, 1988.
41. Torres LFB, Duchen LW - The mutant 'mdx': inherited myopathy in the mouse. Morphological studies of nerves, muscles and end-plates. Brain 110-269, 1987.
42. Waerhaug O, Korneliussen H - Morphological types of motor nerve terminals in rat hindlimb muscles, possibly innervating different muscle fibre types. Z Amat Entwicklungs-gesch (Berlin) 144:237, 1974.

Datas de Publicação

Publicação nesta coleção
06 Jun 2011
Data do Fascículo
Jun 1989

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

[1] 1. Banker BQ, Kelly SS, Robbins N - Neuromuscular transmission and correlative morphology in young and old mice. J Physiol 339:355, 1983.

[2] 2. Banker BQ, Hirst NS, Chester CS, Fok RY - Histometric and electron cytochemical study of muscle in the dystrophic mouse. Ann New York Acad Sci 317:374, 1979.

[3] 3. Beam KG, Caldwell JH, Campbell DT - Na channels in skeletal muscle concentrated near the neuromuscular junction. Nature 313:588, 1985.

[4] 4. Betz W, Sakmann B - Effects of proteolytic enzymes on function and structure of frog neuromuscular junctions. J Physiol 230:673, 1973.

[5] 5. Blaxter KL - Myopathies in animals. In Walton J: Disorders of Voluntary Muscle. Churchill Livingstone, Edinburgh, 1974.

[6] 6. Bowden, REM, Duche LW - The anatomy and pathology of the neuromuscular junction. In Zaimis E: Handbook of Experimental Pharmacology. Springer, Berlin, 1976.

[7] 7. Bradley R, Fell BF - Myopathies in animals. In Walton J: Disorders of Voluntary Muscle. Churchill Livingstone, Edinburgh, 1981.

[8] 8. Brook G, Torres LF, Gopalakrishnakone P, Duchen LW - Effects of phospholipase of Enhydrina schistosa venom on nerve, motor end-plate and muscle of the mouse. Quart J Experi Physiol 72:571, 1987.

[9] 9. Buchthal F, Schmalbruch H - Motor unit of mammalian muscle. Physiol Rev 60:90, 1980.

[10] 10. Coers C - Morphologie de la jonction neuro-musculaire. Arch Biol (Liege) 75 (suppl): 905, 1964.

[11] 11. Couteaux R - Morphological and cytochemical observations on the post-synaptic membrane at motor end-plates and ganglionic synapses. Exper Cell Res 5 (suppl):294, 1958.

[12] 12. Duchen LW - An electron microscopic comparison of motor end-plates of slow and fast skeletal muscle fibres of the mouse. J Neurol Sci 14:37, 1970.

[13] 13. Duchen LW, Excell BJ, Patel R, Smith B - Changes in motor end-plates resulting from muscle fibre necrosis and regeneration: a light and electron microscopic study of the effects of the depolarizing fraction of Dendroaspis jamesoni venom. J Neurol Sci 21:391, 1974.

[14] 14. Ellisman MH - The membrane morphology of the neuromuscular junction, sarcolemma, sarcoplasmic reticulum and transverse tubule system in murine muscular dystrophy studied by freeze-fracture electron microscopy. Brain Res 214:261, 1981.

[15] 15. Engel AG, Santa T - Histometric analysis of the ultrastructure of the neuromuscular junction in myasthenia gravis and in the myasthenic syndrome. Ann New York Acad Sci 183: 46, 1971.

[16] 16. Engel AG, Jerusalem F, Tsujihata M, Gomez MR - The neuromuscular junction in myopathies: a quantitative ultrastructural study. Recent Advances in Myology 360:132, 1974.

[17] 17. Fahim MA, Robbins N - Ultrastructure studies of young and old mouse neuromuscular junctions. J Neurocytol 11:641, 1982.

[18] 18. Fardeau M - Ultrastruture des jonctions neuromusculaires dans la musculature sque-_ lettique du cobaye. In Israel M, Manaranche R: La Transmission Cholinergique de L'Excitation. Inserm, Paris, 1973.

[19] 19. Grinnell AD, Herrera AA - Specificity and plasticity of neuromuscular connections: long-term regulation of motor neuron function. Progress in Neurobiol 17:203, 1981.

[20] 20. Gwyn DG, Aitken JT - The formation of new end-plates in mammalian skeletal muscle. J Anatomy 100: 116, 1966.

[21] 21. Harriman DGF - A comparision of the fine structure of motor end-plates in Duchenne dystrophy and in human neurogenic diseases. J Neurol Sci 28:233, 1976.

[22] 22. Hopkins WG, Brown MC, Keynes RJ - Postnatal growth of motor nerve terminals in muscles of the mouse. J Neurocyt 14:525, 1985.

[23] 23. Jirmanova I - Ultrastructure of motor end-plates during pharmacologically induced degeneration and subsequent regeneration of skeletal muscle. J Neurocytol 4:141, 1975.

[24] 24. Kakulas BA - Experimental Myopathies. In Walton J: Disorders of Voluntary Muscle. Churchill Livingstone, Edinburgh, 1981.

[25] 25. Kakulas BA - Toxic and drug-induced myopathies. In Mastaglia FL, Walton J: Skeletal Muscle Pathology. Churchill Livingstone, Edinburgh, 1982.

[26] 26. Karnovsky MJ - A formaldehyde-gluraraldehyde fixative of high osmolarity for use in electron microscopy. J Cell Biol 27:137A, 1965.

[27] 27. Koenig J - Morphogenesis of motor end-plates 'in vivo' and 'in vitro'. Brain Res 62:361, 1973.

[28] 28. Law PK, Saito A, Fleischer S - Ultrastructural changes in muscle and motor end-plate of the dystrophic mouse. Exper Neurol 80:361, 1983.

[29] 29. McMahan UJ, Edgington DR, Kuffler DP - Factor that influence regeneration of the neuromuscular junction. J Exper Biol 89:31, 1980.

[30] 30. Namba T, Nakamura T, Grob D - Staining for nerve fibre and cholinesterase activity in fresh frozen sections. Am J Clin Pathol 47:74, 1967.

[31] 31. Ontell M, Haller E - Necrotic extrafusal muscle fibres of the dystrophic mutant mouse: the ultrastructure of the myoneural junction. Anat Rec 197:397, 1980.

[32] 32. Padykula HA, Gauthier GF - The ultrastructure of the neuromuscular junction of mammalian red, wthite and intermediate skeletal muscle fibres. J Cell Biol 46:27, 1970.

[33] 33. Pestronk A, Drachman D - A new stain for quantitative measurement of sprouting at neuromuscular junctions. Muscle and Nerve, 1:70, 1978.

[34] 34. Queiroz LS - Effects of neurotoxins on muscle and nerve in the mouse: morphological and physiological studies. Tese PhD. Universidade de Londres, Inglaterra, 1981.

[35] 35. Santa T, Engel AG - Histometric analysis of neuromuscular junction ultrastructure in rat red, white and intermediate muscle fibres. In Desmedt JE: New Developments in EMG and Clinical Neurophysiology. Karger, Basel, 1973.

[36] 36. Snell RS, Mclntyre N - Effect of denervation on the histochemical appearance of cholinesterase at the myoneural junction. Nature 176:884, 1955.

[37] 37. Snell RS, Mclntyre N - Changes in the histochemical appearances of cholinesterase at the motor end-plate following denervation. Br J Exper Pathol 37 (1), 1956.

[38] 38. Telford IR, Einarson L - Experimental muscular dystrophies in animals. Charles Thomas, USA, 1971.

[39] 39. Torres LFB - Muscle, motor end-plate and nerves in hereditary and experimental myopathies in the mouse. Tese PhD. Universidade de Londres, Inglaterra, 1986.

[40] 40. Torres LFB - Inherited neuromuscular diseases in the mouse: a review of the literature. Arq Neuro-Psiquiat (São Paulo) 46:298, 1988.

[41] 41. Torres LFB, Duchen LW - The mutant 'mdx': inherited myopathy in the mouse. Morphological studies of nerves, muscles and end-plates. Brain 110-269, 1987.

[42] 42. Waerhaug O, Korneliussen H - Morphological types of motor nerve terminals in rat hindlimb muscles, possibly innervating different muscle fibre types. Z Amat Entwicklungs-gesch (Berlin) 144:237, 1974.