Ultrastructural identification of protein bodies, cellular markers of human catecholamine neurons, in a temporal lobe ganglioglioma.

A temporal lobe ganglioglioma, surgically removed from an 8-year-old body, and a human brainstem at the level of locus coeruleus (LC) were processed for light microscopy (LM), with formalin fixation and paraffin embedding, and for electron microscopy (EM) with glutaraldehyde fixation, potassium permanganate postfixation, phosphotungstic acid-hematoxylin block-staining, and epoxy resin embedding. The paraffin sections were stained with toluidine blue O/rhodamine B and observed under epi-fluorescence. The thin sections for EM were viewed directly without further staining. The neuronal neoplastic cells of ganglioglioma and the neurons of LC are known to produce catecholamines. Both also contain spherical protein bodies (pb), cellular markers that identify catecholamine neurons in humans. The ultrastructural characteristics of the pb in LC were compared with those of the pb in neoplastic ganglion cells. These bodies had an identical ultrastructure, in both tissues, consisting of electron-lucent core surrounded by an electron-dense thin rim. The rhodamine B-stained sections also emphasized the identical morphology of the pb in ganglioglioma and LC. Based on the EM comparison, these brightly fluorescing spherical bodies are ideal markers for identifying in LM, the clusters of large neoplastic cells, representing neurons, which are the most important clue to the correct diagnosis of gangliogliomas.

Distribution of ubiquitin immunoreactivity in dopamine neurons of chronic alcoholics.

In animal experiments drugs of abuse, including alcohol, have been shown to stimulate and affect dopamine neurons, which mediate their rewarding effects. In this study, the aim was to establish cellular effects of alcohol on human dopamine neurons, by investigating midbrain from 27 chronic alcoholics (33-84 years old) and 10 matched controls. We used polyclonal antibodies to ubiquitin, a marker which localizes lesions of the cellular stress caused by alcohol, on paraffin sections. Results showed that the grading of ubiquitin immunoreactivity (UBQ-IR) distribution differentiated two groups of alcoholics. The first was characterized by low average age and liver cirrhosis, the second by greater average age and absence of cirrhosis. In the first group UBQ-IR was distributed in dendrites and cell bodies of dopamine neurons, mostly along their membranes. In the second group dopamine neurons were negative, UBQ-IR was confined to dystrophic neurites in the neuropil. These data indicate that human dopamine neurons in chronic alcoholics of the first group, are metabolic targets of the stressful action of alcohol, revealed by UBQ-IR. The results also provide evidence that the second group of users, lacking cellular localization of UBQ-IR, have developed protective compensatory mechanisms to the membrane disruption caused by alcohol, due to a different genetic constitution.