The molecular properties of murine mSOD1 facial motoneurons and surrounding neuropil following facial nerve axotomy

Amyotrophic lateral sclerosis (ALS) involves a rapid and fatal degeneration of motoneurons (MN) in the brain and spinal cord. A transgenic animal model (mSOD1) has been established to examine ALS. Recent evidence has shown that disease progression in mSOD1 mice results in two transient populations of MN, one compensatory and one degenerative. We have also discovered similar populations of MN following facial nerve transection. Thus, facial nerve axotomy can be used as a tool to examine the molecular properties of diseased MN in pre‐symptomatic mSOD1 mice. In the ventral medial (VM) facial subnucleus, there is 100% cell survival following axotomy in wild‐type (WT) mice and 60% in mSOD1 mice, while in the ventral lateral (VL) facial subnucleus, there is a significant reduction in cell survival for both WT (70%) and mSOD1 (20%). Molecular properties were characterized in both WT and mSOD1 mice following facial nerve axotomy via laser microdissection and real‐time PCR, in situ hybridization, and immunocytochemistry. The results support two distinct molecular phenotypes associated with cell survival or death following axotomy in both WT and mSOD1 mice. Supported by the Les Turner ALS Foundation (NAM and KJJ).