Multiple transmitter systems contribute neurites to individual senile plaques - PubMed (original) (raw)

Multiple transmitter systems contribute neurites to individual senile plaques

L C Walker et al. J Neuropathol Exp Neurol. 1988 Mar.

Abstract

Senile plaques (SP), which consist largely of abnormal neuronal processes in proximity to deposits of amyloid, are a characteristic neuropathological feature of Alzheimer's disease. In lesser numbers, SP also occur in the brains of nondemented aged humans and nonhuman primates. To date, it is not known whether neurites in individual SP derive from neurons of one or several neurotransmitter systems. In aged monkeys, two strategies were used to test the hypothesis that individual SP can contain abnormal neurites arising from multiple neuronal systems. First, immunocytochemical methods were used to identify somatostatin-immunoreactive neurites in plaques, and these sections were subsequently stained with silver to visualize other neurites. Numerous plaques contained both somatostatin-positive and somatostatin-negative (i.e. argyrophilic only) neurites, suggesting that more than one transmitter system contributed neurites to each of these plaques. Second, two-color immunocytochemical techniques showed, in a small percentage of plaques, that cholinergic neurites coexist with neuropeptide Y (NPY)-containing neurites or catecholaminergic neurites. These results suggest that the formation of SP may result from events that involve abnormalities of neuronal processes arising from multiple transmitter systems.

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Figures

Figure 1.

Figure 1.

A. Abnormal somatostatin-immunoreactive neurites (thin arrows) in a senile plaque in the amygdala of the 26-year-old rhesus monkey. B. The same plaque as in Figure 1A, post-stained using a nonspecific silver stain [15]. Thin arrows designate the somatostatin-immunoreactive neurites indicated in Figure 1A. Thick arrows show two neurites that were not stained previously for somatostatin. Many surrounding circular and elliptical structures are silver-stained cell nuclei. Bar = 20 microns.

Figure 2.

Figure 2.

A. Neocortical senile plaque double-immunostained for choline acetyltransferase/DAB (light brown in original publication) and NPY/BDHC (granular blue in original publication). The black arrow indicates an abnormal cholinergic neurite, and the white arrow indicates an abnormal NPY-containing neurite. Numerous additional, partially overlapping neurites are also present. B. Choline acetyltransferase-immunoreactive neuron in the nucleus basalis of Meynert in the same tissue section as the plaque in Figure 2A. C. Neuropeptide Y-immunoreactive neuron in the neocortex, also from the same tissue section as the plaque in Figure 2A. This section was taken from the 28-year-old rhesus monkey. Bars = 20 microns.

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