Figure 9.
Model correlating changes in axonal transport balance with disease severity and time course: slowing of retrograde transport is an early step that leads to slowly progressive motor neuron degeneration, because of decreased trophic factor signaling, as seen in the Loa and Tgdynamitin models, whereas changes in the nature of the signals undergoing retrograde transport by 50 d (presymptomatic) lead to more severe and more rapidly progressive degeneration by 120 d (severe symptoms and late stage of disease), as seen in the SOD1G93A model. Disease stages were classified based on symptoms like weight loss, walking difficulty, and muscle atrophy. Time scale for the SOD1G93A is shown. Sym, Symptomatic.