Extracellular matrix organization in various regions of rat brain grey matter

Abstract

Previous studies revealed the concentration of extracellular matrix proteoglycans in the so-called perineuronal nets on the one hand and in certain zones of the neuropil on the other. This nonhomogeneous distribution suggested a non-random chemical and spatial heterogeneity of the extracellular space. In the present investigation, regions dominated by one of both distribution patterns, i.e. piriform and parietal cortex, reticular thalamic nucleus, medial septum/diagonal band complex and cerebellar nuclei, were selected for correlative light and electron microscopic analysis. The labelling was performed by the use of the N-acetylgalactosamine-binding plant lectin Wisteria floribunda agglutinin visualized by peroxidase staining and additionally by photoconversion of red carbocyanine fluorescence labelling for electron microscopy. The intense labelling of the neuropil of a superficial piriform region, presumably identical with sublayer Ia, was confined to a fine meshwork spreading over the extracellular space between non-myelinated axons, dendrites and glial profiles. In the reticular thalamic nucleus the neuronal cell bodies were embedded in zones of labelled neuropil. In contrast to these patterns, the labelled extracellular matrix in different cortical layers and in the other subcortical regions was concentrated in perineuronal nets as large accumulations at surface areas of the neuronal perikarya and dendrites and the attached presynaptic boutons. Astrocytic processes usually were separated from the neuronal surface by the interposed extracellular material. Despite a great variability, the width of the extracellular space containing the labelled matrix components in all perineuronal nets appeared to be considerably larger than that in the labelled zones of neuropil and the non-labelled microenvironment of other neurons. Our results support the view that differences expressed in topographical and spatial peculiarities of the extracellular matrix constituents are related to neuron-type and system-specific functional properties.

The Extracellular Matrix Protein Brevican Limits Time-Dependent Enhancement of Cocaine Conditioned Place Preference

“…Remarkably, we observed substantial colocalization of virally induced brevican expression within the PV population of the mPFC, pointing to a yet-unknown mechanism that directs brevican expression to this cell type. In line with our finding is the well-established observation that PNNs predominantly enwrap PV neurons in the cortex and hippocampus (Bruckner et al, 1996;Van den Oever et al, 2010), suggesting a shared molecular process that regulates condensation of structural ECM proteins at PV neurons in the cortex. Changes in PNNs have been shown to affect the firing properties of PV cells, thereby influencing GABAergic control over pyramidal cell activity (Dityatev et al, 2007).…”

Saccadic omnipause and burst neurons in monkey and human are ensheathed by perineuronal nets but differ in their expression of calcium‐binding proteins

“…Other parameters, such as the strength, activity, and/or transmitters of the synaptic input to the ensheathed neurons might affect the presence of perineuronal nets (Celio and Blü mcke, 1994) or appearance of perineuronal net labeling (Seeger et al, 1994;Brü ckner et al, 1996). It can vary from rather diffuse neuropil labeling, e.g., in the reticular thalamic nucleus, and strong pericellular staining continuous with the strong labeling of the neuropil, e.g., in subthalamic nucleus ( Fig.…”

Semaphorin 3A Binds to the Perineuronal Nets via Chondroitin Sulfate Type E Motifs in Rodent Brains

“…Although the PNNs are distributed in several areas in the rat brain, in the cerebral cortex, PNNs are mainly associated with GABAergic interneurons (33,34). Sema3A co-localization with PNNs was particularly strong in layers IV and V in the cerebral cortex and was mainly associated with parvalbumin-positive interneurons (1).…”