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KMID : 0350519960490020689
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Journal of Catholic Medical College
1996 Volume.49 No. 2 p.689 ~ p.704
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Astroglial Reactions in the Superior Colliculus of the Rat after Unilateral Enucleation
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Abstract
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It has been reported that astrocytes repair brain defects induced by variable reasons through their proliferation, migration to injury site or hypertrophy. This study was conducted in order to clarify how astrocytes react in process of restoring
in
superior colliculus after unilateral enucleation. We examined astroglial reaction in rat superior colliculus after enucleation of the right eye by immunohistochemistry using anti-S-100 protein, glial fibrillary acidic protein (GFAP) and
proliferating
cell nuclear antigen (PCNA) antisera, and by electron microscopic immunocytochemistry for GFAP.
1. In normal rats, GFAP immunoreactivity was mainly observed in the cytoplasmic processes of astrocytes, and the labeled astrocytes were mainly located in the zonal layer and the periphery of the blood vessels of the superficial gray layer. In
enucleated rats, GFAP immunoreactive astrocytes showed a quite different distribution pattern in both sides of the superior colliculus. In the right superior colliculus, the distribution pattern of the GFAP positive cells is similar to that of
the
normal rats. But in the left superior colliculus, the thickness, length and branching degree of the GFAP positive cytoplasmic processes were remarkably increased in accordance with the duration time after enucleation.
2. In normal rats, S-100 protein immunoreactivity was observed in the nuclei and somata of astrocytes and the labeled astrocytes were evenly distributed in the superficial gray layer of the superior colliculus. The numbers of S-100 protein
positive
astrocytes in unit area (2×10E4㎛*) of the superificial gray layer were 4.3±1.5 (3.9±1.6~4.6±1.6). In enucleated rats, the numerical changes of the S-100 protein immunoreactive cells were not significnant according to the experimental
condition.
3. PCNA immunoreactivity is only detected on the blood cells in the blood vessels at the left superior colliculus of the enucleated rat.
4. Astrocytic processes filled with GFAP positive intermediate filaments appeared near or in close contact with the degenerative nerve terminals over the gray matter of the superficial gray layer in the enucleated rat.
These results suggest that retinal ganglion cells project mainly to the contralateral superior colliculus, and the defect in the superficial gray layer of the superior5 colliculus induced by enucleation is repaired through the hypertrophy of the
astrocytes.
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