Ubiquitin-positive degenerating neurites in the brainstem in Parkinson's disease.

Characteristic ubiquitin-positive, tau-negative, degenerating neurites were present in brainstem regions known to be involved in idiopathic Parkinson's disease. Corresponding changes were entirely absent from controls and from the brainstems obtained from patients who had died with Alzheimer's disease, motor neuron disease and multiple system atrophy. In Parkinson's disease cases degenerating neurites were particularly striking in the dorsal motor nucleus of the vagus. In this nucleus the density of degenerating neurites was inversely related to the duration of Parkinson's disease symptoms. Some ubiquitin-positive degenerating neurites also contained neurofilament immunoreactivity. However, confocal microscopy revealed that ubiquitin and neurofilament reactivities were located in separate regions of the degenerating neurite, suggesting that proteins other than neurofilaments may be important in the process of ubiquitination. The demonstration of ubiquitin-positive degenerating neurites in routinely prepared paraffin-embedded material, particularly in the dorsal motor nucleus of the vagus, could become diagnostically useful in those Parkinson's disease cases in which Lewy bodies are difficult to find. Demonstration of extensive ubiquitin-positive degenerating neurites might provide a clue to disease activity at the time of death.