神経筋疾患の組織化学的研究

The Histochemical Studies of Skeletal Muscle in the Investigation of Neuromuscular Diseases

Ⅰ．緒言

　多くの神経筋疾患のなかには，筋萎縮が躯幹近位部より始まるもの，あるいは，四肢末梢部より始まるものなどさまざまで，一部にはその発生様式に疾患特異性がうかがわれるものもある。これは身体部位により，骨格筋の神経支配の相違および，エネルギー代謝などになんらかの差異があるためと考えられる。

　骨格筋のこれら機能分化に関しては，古くは1874年Ranvier^1）の肉眼的観察による白筋・赤筋の分類に始まり，Denny-Brown^2）は，さらに組織学的に骨格筋は白筋線維，赤筋線維の混合により構成されていることを明らかにした。またKrűger^3）は生理機能の面から追求し，霞気刺激に対する筋線維の反応の差よりtetanusに関係する筋線維群と，tonusに関係する筋線維群とを分類した。おが国においても，時実^4）は骨格筋の収縮活動の機能的単位は1本の筋線維ではなく，1コの脊髄前柱細胞と，その支配下にある紳経筋線維群（neuromuscular unit，NMU．）であるとして，筋電図の立場からkinetic NMU．，tonic NMU．とを分離している。同様に沼本^6），更井^5），陣内^7）らは一連の筋電図学的研究から，kinetic NMU．はphasicな放電活動を示し，錐体路支配を受け，tonic NMU．はtonicな放電活動を示し錐体外路によつて支配されていることを明らかにしている。

　Skeletal muscle tissue was obtained by biopsy from 60 patients suspected of having various neuromuscular disease. The biopsy specimen was rapidly frozen and from it 18 to 20 μ thick serial sections were cut in a cryostat.

　The activities of phosphorylase (PhR, Takeuchi & Kuriaki's method, 1954) and mitochondrial oxidative, enzymes such as reduced diphosphopyridine-nucleotide diaphorase (DPNH, Modified method of Novikoff et al. stain, 1961), DPN-linked lactic dehydrogenase (LDH. Modified method of Pearst et al. stain, 1958) and succinic dehydrogenase (SDH, Modified method of Nachlas et al. stain, 1957) were studied by histochemical techniques in the biopsy specimen.

　The relationship of these enzymatic activity to fiber diameter was also studied.

　The results were as follows: 1) In neurogenic atrophic muscle fibers exceptserious atrophy, the activity of PhR and oxidative enzymes (LDH, SDH, DPNH) and the relationship between the activity of enzymes and the size of the muscle fibers, did not differ from the normal controls. But in far advanced cases the atrophied fibers (less than 20 μ in diameter) were always associated with a low or complete abscence of enzymatic activity, especially PhR reaction. A specific relationship between muscle fiber type (white, and red fiber) and size alterations shown by Fenichel and Engel in infantile spinal muscular atrophy was not evident in all neurogenic cases studied.

　2) In myogenic atrophic muscle, a specific relationship exists between muscle fiber type and size alterations except muscle dystrophy.

　The impairment of PhR and oxidative enzyme reaction were already seen in early stage of atrophy (muscle fiber almost normal size).

　The most striking feature a decrease in diameter of white muscle fiber (higher activities of PhR), indicating a atrophy of this fiber type in all cases (except muscle dystrophy), while red muscle fibers (grater activity of oxidative enzyme) are altered little.

　3) In dystrophic muscle, associated with decrease of PhR and oxidative enzyme activities, generally there was no relationship between the intensities of enzyme activities and fiber size.