Immunohistochemical localization of brain-derived neurotrophic factor in the spinal cords of amyotrophic lateral sclerosis and non-amyotrophic lateral sclerosis patients

Brain-derived neurotrophic factor (BDNF) has a trophic effect on several neuronal subtypes including motor neurons. To localize and assess BDNF in the human spinal cord with particular reference to amyotrophic lateral sclerosis (ALS), we immunohistochemically studied spinal cords from 8 ALS and 13 non-ALS patients. Punctate staining for BDNF was observed in neuronal somata and proximal processes of large-sized anterior horn cells of non-ALS patients, as were distal axons immunolabeled in the neuropil. The same immunostaining pattern was found in thr anterior horn cells of ALS patients. Neurons of the dorsal nucleus of Clarke, intermediolateral nucleus, and posterior horn sensory system were also stained in both groups. The results suggest that BDNF may act widely as a trophic factor in the human spinal cord, and motor neurons in ALS patients might be sufficiently supplied with endogenous BDNF from other neuronal subpopulations in the spinal cord.