Apparent scarcity of glial fibrillary acidic protein expression in the brain of the pygmy shrew Sorex minutus as revealed by immunocytochemistry.
We examined astroglial cells in the brain of the pygmy shrew Sorex minutus (Insectivora). For that purpose we labeled glial fibrillary acidic protein (GFAP) immunohistochemically in brain sections with a polyclonal antibody. Antigen retrieval experiments were performed to counteract formaldehyde fixation masking of GFAP epitopes. Our results showed remarkable paucity of GFAP-immunoreactive cells and fibers in the cerebral cortex and nuclei, as well as in the majority of the diencephalic and mesencephalic structures. In the forebrain, significant numbers of GFAP-containing astrocytes were found only in the ependyma and subventricular zones, superficial part of layer I of the cerebral cortex, and the majority of white matter structures. In the diencephalon, habenular nuclei were rich in GFAP-immunopositive astrocytes and labeled radial fibers were extended between median eminence and the third ventricle. A considerably higher density of labeled astrocytes was detected in the caudal brainstem and cerebellum. In contrast, in the mouse brain, immunoreactive astrocytes were present in large quantities in various structures. Staining of sections of the shrew brain against glutamine synthetase revealed abundance of immunofluorescent astrocytes in many areas, especially in the shrew cerebral cortex. It seems probable that in the shrew brain only a limited fraction of astroglia expresses GFAP, while other astroglial cells can be detected with different markers. It is possible that the rodent type of astroglial GFAP expression might not be common to insectivores and probably to some other mammalian orders.
Olkowicz
Seweryn
S
Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland. s.olkowicz@nencki.gov.pl
Bartkowska
Katarzyna
K
Rychlik
Leszek
L
Turlejski
Kris
K
D000818:Animals; D001921:Brain / Q000166:cytology / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism*; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism; D007150:Immunohistochemistry / Q000379:methods; D051379:Mice; D009457:Neuroglia / Q000378:metabolism; D012788:Shrews
D005904:Glial Fibrillary Acidic Protein; D005974:Glutamate-Ammonia Ligase