[Neuromuscular abnormalities in disuse, ageing and cachexia].
Cachexia, ageing and disuse and their effects on the human and animals neuromuscular system are reviewed. Disuse induces reduction of muscle fibers (mainly II) diameter with peripheral myofibrils lost; there is no core-targetoid or even reduction on myophosphorilase activity, both typical of denervation; the acetylcholine spontaneous release and trophic factors on myoneural junction are maintained; muscle fibers could change to angular shape. Ageing affects nerve and muscle by a continuous and progressive process of denervation and reinnervation; the number of motor units diminishes in sixties without any denervation electric activity; there is also reduction on the amount of ACh release on terminal neurons and mitochondrial oxidative capacity leading to compensatory type I muscle fiber number increase. Cachexia also induces reduction on muscle fibers diameter first on legs and then on arms and trunk; there is type II atrophy with occasional angular fibers, RNA/proteic synthesis reduction and normal DNA.
Kouyoumdjian
J A
JA
Disciplina de Neurologia da Faculdade de Medicina, São José do Rio Preto.
D000368:Aged; D000375:Aging / Q000502:physiology*; D000818:Animals; D002100:Cachexia / Q000503:physiopathology*; D002415:Cats; D015444:Exercise; D006168:Guinea Pigs; D006801:Humans; D007103:Immobilization / Q000009:adverse effects; D009133:Muscular Atrophy / Q000209:etiology* / Q000473:pathology; D009469:Neuromuscular Junction / Q000503:physiopathology*; D051381:Rats
Anormalidades neuromusculares no desuso, senilidade e caquexia.