Dysmyelinated lower motor neurons retract and regenerate dysfunctional synaptic terminals.

Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA.
Journal of Neuroscience (Impact Factor: 6.75). 05/2004; 24(15):3890-8. DOI: 10.1523/JNEUROSCI.4617-03.2004
Source: PubMed

ABSTRACT Axonal degeneration is the major cause of permanent neurological disability in individuals with inherited diseases of myelin. Axonal and neuronal changes that precede axonal degeneration, however, are not well characterized. We show here that dysmyelinated lower motor neurons retract and regenerate dysfunctional presynaptic terminals, leading to severe neurological disability before axonal degeneration. In addition, dysmyelination led to a decreased synaptic quantal content, an indicator of synaptic dysfunction. The amplitude and rise time of miniature endplate potentials were also increased, but these changes were primarily consistent with an increase in the passive membrane properties of the transgenic muscle fibers. Maintenance of synaptic connections should be considered as a therapeutic target for slowing progression of neurological disability in primary diseases of myelin.

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