Early Hypoexcitability in a Subgroup of Spinal Motoneurons in Superoxide Dismutase 1 Transgenic Mice, a Model of Amyotrophic Lateral Sclerosis

In amyotrophic lateral sclerosis (ALS), large motoneurons degenerate first, causing muscle weakness. Transgenic mouse models with a mutation in the gene encoding enzyme superoxide dismutase 1 (SOD1) revealed that innervating fast-fatigable muscular fibres disconnect very early. The cause of this peripheric disconnection has not yet been established. Early pathological signs were described during postnatal period SOD1 transgenic mice. Here, we investigated whether early changes electrical and morphological properties previously reported SOD1G85R strain also occur SOD1G93A-low expressor line particular attention to different subsets defined by their discharge firing pattern (transient, sustained, or delayed-onset firing). Intracellular staining recording performed lumbar from entire brainstem-spinal cord preparations mice WT littermates second week. Our results show exhibit dendritic overbranching similar at same age. Further found an hypoexcitability (lower gain higher voltage threshold). We conclude are common features both low mutants (G85R G93A-low). high-expressor SOD1G93A line, hyperexcitability sustained period, suggesting delay compensatory mechanisms. Overall, our suggest indicate dysfunction could account as disease.