Noradrenaline storage function of species-specific protein bodies, markers of monoamine neurons in human locus coeruleus demonstrated by dopamine-beta-hydroxylase immunogold localization

Our histochemical and ultrastructural studies have identified, in human catecholamine locus coeruleus (LC) neurons, abundant and large spherical protein bodies (PB), containing histone-like, arginine-rich proteins, which originate as dense bodies in mitochondria. This species-specific phenotype in the neurons of man is highly intriguing. In the electron microscope PB are disrupted in LC neurons in depressed individuals, where noradrenaline is known to be reduced. This coincidence of ultrastructure and neurochemistry raises the question whether these bodies Could qualify as noradrenaline-storing organelles in the human LC. Our rationale was to examine, in known model tissues that contain catecholamines-sympathetic ganglia and tumors of the autonomic nervous system-if vesicles show the same fine structure and histochemistry as the PB of the human LC. Hence, we selected biopsy tissues of five ganglioneuromas and postmortem tissues of LC from 25 control subjects. Since dopamine-beta-hydroxylase (DBH) is a hallmark of noradrenaline identity and present in dense core vesicles, the investigation of DBH localization with the immunogold method constituted the experiment of choice for this study. Histochemical determinations of arginine with Carmoisine L, and of lipids with Rhodamine B complemented the study of similarities between the PB of the human LC and ganglioneuromas. Our results showed, with the colloidal gold method, that DBH immunogold labeling was localized in the core and in the double membranes of the PB, and also in the adjacent mitochondria. These results indicate that protein bodies (a) are unequivocal storage vesicles of noradrenaline, and (b) derive from regular mitochondria and represent a new phenotype in man, which is probably an evolutionary adaptation of amine-storing organelles. (C) 2004 Elsevier Inc. All rights reserved

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