Axonal Regeneration and Neuronal Function Are Preserved in Motor Neurons Lacking ß-Actin In Vivo

The proper localization of ß-actin mRNA and protein is essential for growth cone guidance and axon elongation in cultured neurons. In addition, decreased levels of ß-actin mRNA and protein have been identified in the growth cones of motor neurons cultured from a mouse model of Spinal Muscular Atrophy (SMA), suggesting that ß-actin loss-of-function at growth cones or pre-synaptic nerve terminals could contribute to the pathogenesis of this disease. However, the role of ß-actin in motor neurons in vivo and its potential relevance to disease has yet to be examined. We therefore generated motor neuron specific ß-actin knock-out mice (Actb-MNsKO) to investigate the function of ß-actin in motor neurons in vivo. Surprisingly, ß-actin was not required for motor neuron viability or neuromuscular junction maintenance. Skeletal muscle from Actb-MNsKO mice showed no histological indication of denervation and did not significantly differ from controls in several measurements of physiologic function. Finally, motor axon regeneration was unimpaired in Actb-MNsKO mice, suggesting that ß-actin is not required for motor neuron function or regeneration in vivo

Etude comparative des données histochimiques et de l'innervation motrice terminale du muscle strié dans la pathologie neuro-musculaire

Doctorat en sciences médicalesinfo:eu-repo/semantics/nonPublishe

Changes of motor innervation in myasthenic muscles in relation to age

The motor innervation in muscle biopsies from 45 myasthenic patients was studied by intravital staining with methylene blue. The enzymatic pattern and fibre type distribution was analysed in 12 cases. Quantitative data including the proportion of elongated motor endings and the terminal innervation ratio (TIR) of motor axons, were compared to histochemical data and to clinical data including age of patients. The incidence of elongated motor endings tends to be greater in younger patients, whereas an increased collateral ramification of motor axons occurs only after the age of 50. Small type III fibers suggesting denervation are also found in elderly patients only. The significance of these morphological differences in relation to age is discussed.info:eu-repo/semantics/publishe

Fact and fancy in the histological diagnosis of denervation

info:eu-repo/semantics/publishe

L'histochimie des fibres musculaires normales

info:eu-repo/semantics/publishe

Muscle fibre types in denervation

In a large proportion of chronic neuropathies and motor neurone disease, in biopsies taken from clinically little affected muscles, the fibre type grouping is not conspicuous, so that this pattern should not be considered as a hallmark of the morphologic diagnosis of denervation. In this respect, the increased terminal innervation ratio remains a much more reliable parameter. The high proportion of type III or intermediate fibres occurring preferentially in cases without obvious type grouping must be emphasized, with regard to the hypothesis that these fibres represent a transient stage of reinnervation through collateral branching of subterminal axons. The pattern of type I grouping with numeric and sometimes volumetric reduction of type II fibres occurring in obviously neuropathic conditions leads to a reappraisal of the so called type II atrophy observed in disuse atrophy and in some myopathies. A neural influence in these conditions should only be accepted when there are characteristic changes in the terminal motor innervation pattern. (Journal received: 22 Oct. 1974)SCOPUS: NotDefined.jinfo:eu-repo/semantics/publishe

Triparésie spastique "ammoniacale" réversible.

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Complications cerebro-vasculaires de l'hypertension

SCOPUS: ar.jinfo:eu-repo/semantics/publishe