Spinal cord trauma in man: studies of phosphorylated neurofilament and ubiquitin expression.

Changes in neuronal proteins are a major feature of the neurodegenerative disorders, but the biological significance of these changes is not understood. We describe alterations in neuronal proteins as a result of surgical tractotomy on the human spinal cord at 3, 5, 7, 14 and 72 days after operation. Antibodies to phosphorylated neurofilaments labelled neuronal cell bodies in the nucleus dorsalis and anterior horns. Axonal swellings showed positive staining for ubiquitin, but ubiquitinated neuronal inclusions were not evident. The presence of phosphorylated neurofilaments in the neuronal cell bodies and of ubiquitination of axonal swellings may be indicators of interrupted axonal transport. The changes found in intracellular proteins in neurons after trauma do not resemble those found in motor neuron disease, suggesting that the intraneuronal ubiquitinated inclusions may have a unique significance in the cytopathology of that disorder.