Astroglia-Microglia Cross Talk during Neurodegeneration in the Rat Hippocampus
Activation of glucocorticoid receptors (GR) induced by NMDA injection in the hippocampus. (a) Photomicrographs illustrate GR immunohistochemistry in the hippocampus of sham animals and NMDA rats 5 days after the injection. Asterisks indicate the injection site and insets illustrate the GR immunostaining in neurons (arrow) and glial cells (arrowheads). Please note that pyramidal cells (arrows) are much bigger than glia (arrowheads); they also present a pyramidal shape with a dendritic tree, while reactive microglia have a round smaller shape. (b) Graphs show the quantification of the nucleus/cytoplasm ratio of GR-immunolabeling in hippocampal neurons and glial cells of sham (PBS) and NMDA-lesioned rats. Confocal photomicrographs show the double immunohistochemistry of GR (in green) with specific cellular markers (in red) in the hippocampal CA1 layer of NMDA-lesioned rats 5 days after the lesion. NeuN-GR double immunostaining of PBS (c–e) and NMDA (f–h) rats evidences an increased GR-immunolabeling in the nucleus of neurons of NMDA rats (arrowheads). GFAP-GR double immunostaining in PBS (i–k, arrowheads) and NMDA (l–n) rats shows an increased GFAP-immunolabeling in astrocytes of NMDA rats not associated with GR-immunoreactivity changes, which indicates that the NMDA-induced GR activation quantified in panel (b) is not astroglial. CD11b-GR double immunohistochemistry in PBS (o–q) and NMDA (r–t) rats evidences an increased GR-immunolabeling in the nucleus of reactive microglia of NMDA rats. ; different from PBS (Student’s -test) ( rats/group). Bar: 500 μm in (a) and 10 μm in (c)–(t) and insets in (a).
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