title: Distribution and classification of aggrecan-based extracellular matrix in the thalamus of the rat.
abstract: Extracellular matrix molecules take part in functional isolation and stabilization of neuronal compartments but form a vivid interface between neuronal elements at the same time. Previous studies have shown that the accumulation of extracellular matrix, especially its typical phenotypic form, termed perineuronal nets, correlates not only with the functional properties of the single neuron but also with the functional properties of the whole brain area. In contrast to recent advances in investigating neocortex, the present study mapped the occurrence and phenotypic appearance of aggrecan-based matrix accumulation throughout the rat thalamus. Results showed that divisions of thalamus that relay information to cortical fields known rather for their plastic properties exibit a poor matrix immunoreactivity, whereas matrix accumulation is more enhanced in nuclei connected to primary cortical regions. In addition to perineuronal nets, extracellular matrix condensed in another peculiar form, in 2-5-μm, large, round or oval structures, as described by Brückner et al. ([ 2008] Neuroscience 151:489-504) as axonal coats (ACs). Multiple labelling experiments showed that specific excitatory afferents were not ensheathed with these structures. At the same time, inhibitory endings were occasionally enwrapped in ACs. Electron microscopic analysis showed that aggrecan-immunoreactive profiles were present mostly around inhibitory terminals but also in all neuronal compartments. We suggest that aggrecan-based extracellular matrix is formed by both pre- and postsynaptic elements and is preferably associated with inhibitory terminals in the extracellular space.
authors.affiliation: Department of Anatomy, Histology and Embryology, Semmelweis University Medical School, Budapest, Hungary.
authors.forename: Georgina
authors.initials: G
authors.lastname: Gáti
authors.forename: Markus
authors.initials: M
authors.lastname: Morawski
authors.forename: Dávid
authors.initials: D
authors.lastname: Lendvai
authors.forename: Carsten
authors.initials: C
authors.lastname: Jäger
authors.forename: László
authors.initials: L
authors.lastname: Négyessy
authors.forename: Thomas
authors.initials: T
authors.lastname: Arendt
authors.forename: Alán
authors.initials: A
authors.lastname: Alpár
mesh_terms: D053674:Aggrecans / Q000032:analysis* / Q000378:metabolism; D000818:Animals; D005109:Extracellular Matrix / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure*; D005260:Female; D007150:Immunohistochemistry; D008297:Male; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D009415:Nerve Net / Q000737:chemistry / Q000648:ultrastructure; D009474:Neurons / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar; D013788:Thalamus / Q000378:metabolism* / Q000648:ultrastructure*
chemical_list: D053674:Aggrecans