Axonal degeneration in motor neuron disease

Neurodegener Dis. 2007;4(6):431-42. doi: 10.1159/000107704. Epub 2007 Oct 9.


Growing evidence from animal models and patients with amyotrophic lateral sclerosis (ALS) suggests that distal axonal degeneration begins very early in this disease, long before symptom onset and motor neuron death. The cause of axonal degeneration is unknown, and may involve local axonal damage, withdrawal of trophic support from a diseased cell body, or both. It is increasingly clear that axons are not passive extensions of their parent cell bodies, and may die by mechanisms independent of cell death. This is supported by studies in which protection of motor neurons in models of ALS did not significantly improve symptoms or prolong lifespan, likely due to a failure to protect axons. Here, we will review the evidence for early axonal degeneration in ALS, and discuss possible mechanisms by which it might occur, with a focus on oxidative stress. We contend that axonal degeneration may be a primary feature in the pathogenesis of motor neuron disease, and that preventing axonal degeneration represents an important therapeutic target that deserves increased attention.

Publication types

  • Review

MeSH terms

  • Animals
  • Axons / pathology*
  • Disease Models, Animal
  • Humans
  • Mice
  • Mice, Knockout
  • Motor Neuron Disease / pathology*
  • Motor Neuron Disease / physiopathology*
  • Nerve Degeneration / etiology*
  • Nerve Degeneration / pathology*
  • Superoxide Dismutase / genetics
  • Superoxide Dismutase-1


  • SOD1 protein, human
  • Sod1 protein, mouse
  • Superoxide Dismutase
  • Superoxide Dismutase-1