Comparative marker analysis of the ependymocytes of the subcommissural organ in four different mammalian species.
The subcommissural organ (SCO), classified as one of the circumventricular organs, is composed mainly of modified ependymal cells, attributable to a glial lineage. Nevertheless, in the rat, these cells do not possess glial markers such as glial fibrillary acidic protein (GFAP), protein S100, or the enzyme glutamine synthetase (GS). They receive a synaptic 5-HT input and show pharmacological properties for uptake of GABA resembling the uptake mechanism of neurons. In this study, we examine the phenotype of several mammalian SCO (cat, mouse, rabbit) and compare them with the corresponding features of the rat SCO. In all these species, the SCO ependymocytes possess vimentin as an intermediate filament, but never express GFAP or neurofilament proteins. They do not contain GS as do glial cells involved in GABA metabolism, and when they contain protein S100 (rabbit, mouse), its rate is low in comparison to classical glial or ependymal cells. Thus, these ependymocytes display characteristics that differentiate them from other types of glial cells (astrocytes, epithelial ependymocytes and tanycytes). Striking interspecies differences in the capacity of SCO-ependymocytes for uptake of GABA might be related to their innervation and suggest a species-dependent plasticity in their function.
Chouaf
L
L
INSERM U171-CNRS UA 1195, Centre Hospitalier Lyon-Sud, Pierre Bénite, France.
Didier-Bazes
M
M
Aguera
M
M
Tardy
M
M
Sallanon
M
M
Kitahama
K
K
Belin
M F
MF
D000818:Animals; D001345:Autoradiography; D002415:Cats; D004805:Ependyma / Q000032:analysis / Q000166:cytology* / Q000378:metabolism; D005904:Glial Fibrillary Acidic Protein / Q000032:analysis; D005974:Glutamate-Ammonia Ligase / Q000032:analysis; D007124:Immunoenzyme Techniques; D007381:Intermediate Filament Proteins / Q000032:analysis; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009457:Neuroglia / Q000166:cytology / Q000378:metabolism; D009490:Neurosecretory Systems / Q000166:cytology*; D011817:Rabbits; D051381:Rats; D009418:S100 Proteins / Q000032:analysis; D013351:Subcommissural Organ / Q000032:analysis / Q000166:cytology* / Q000378:metabolism; D014746:Vimentin / Q000032:analysis; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D005904:Glial Fibrillary Acidic Protein; D007381:Intermediate Filament Proteins; D009418:S100 Proteins; D014746:Vimentin; D005680:gamma-Aminobutyric Acid; D005974:Glutamate-Ammonia Ligase