Neutrophin switching in spinal motoneurons of amyotrophic lateral sclerosis.

To clarify the roles of neurotrophins in the human spinal motoneurons, with special reference to amyotrophic lateral sclerosis (ALS), we studied the immunohistochemical localizations of neurotrophins and their receptors in spinal cords of patients with ALS and compared them with controls. In the controls, the majority of motoneurons showed BDNF-, NT3-, trkB- and trkC-like immunoreactivity (-LI) suggesting that the motoneurons receive an autocrine regulation by both BDNF and NT3. In ALS patients, about three-quarters of the motoneurons had degenerated and the remaining motoneurons showed significantly decreased BDNF-LI, increased NGF- and trkA-LI. These findings indicated neurotrophin-switching in the remaining spinal motoneurons of ALS patients from BDNF and NT3 responsive to NGF responsive.