Neuromuscular dysfunction in the mutant superoxide dismutase mouse model of amyotrophic lateral sclerosis.

To better understand the interaction between motor neuron dysfunction and denervation in amyotrophic lateral sclerosis (ALS), we have evaluated motor neuron number and the retrograde uptake and transport of fluorogold by motor neurons in mice overexpressing mutant superoxide dismutase (mSOD), and wild-type controls. N-CAM immunoreactivity and protein kinase expression were determined in skeletal muscle during denervation. We found that in severely affected mSOD mice, motor neuron loss is moderate (approximate 40% reduction), whereas retrograde uptake/transport as assessed using fluorogold is profoundly impaired (approximately 90% reduction).