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Astrocytal changes in the white matter of Jimpy mice: immunohistochemistry using antisera to glial fibrillary acidic
Abstract:
Immunohistochemistry using antisera to glial fibrillary acidic protein (GFAP) was performed to observe astrocytal changes in the white matter of myelin-deficient Jimpy mice. In wild-type controls, astrocytes stained with the GFAP immunoreaction appeared in the cerebellar medulla by postnatal day 3 and in the corpus callosum by postnatal day 6. The immunoreactivity gradually intensified with age to reach a peak of the GFAP level around postnatal day 12. With the progress of myelinogenesis, GFAP positive astrocytes decreased in number and became sparse in the white matter. On the other hand, the white matter of Jimpy mutant mice revealed intensified GFAP immunoreactivity, corresponding to a numerical increase in astrocytes and an enlargement of their cytoplasm. This condition continued from postnatal day 12 up to the end of life. Such astrocytes made up a dense framework with thickened processes in the non-myelinated white matter, where oligodendrocytes were few. Under the electron microscope, an accumulation of gliofilaments and glycogen particles was apparent in the enriched astrocytal cytoplasm. Immunostaining was observed not only on gliofilament bundles but also rough endoplasmic reticulum and cytoplasmic matrix. The present results demonstrate that astrocytal hypertrophy and hyperplasia occur in the entire white matter of Jimpy mice.
Insights
Jimpy mice, which lack myelin, show significant astrocyte changes. These glial fibrillary acidic protein (GFAP)-positive cells increase in number and size, indicating hypertrophy and hyperplasia in their white matter.
Area of Science:
- Neuroscience
- Cell Biology
- Developmental Biology
Background:
- Astrocytes play crucial roles in central nervous system homeostasis.
- Glial fibrillary acidic protein (GFAP) is a key intermediate filament protein in astrocytes.
- Myelination is essential for proper neuronal function and white matter integrity.
Purpose of the Study:
- To investigate astrocytal changes in the white matter of myelin-deficient Jimpy mice.
- To characterize the expression and distribution of GFAP in Jimpy mice compared to wild-type controls.
Main Methods:
- Immunohistochemistry using antisera to GFAP.
- Light and electron microscopy.
- Comparative analysis between Jimpy mutant mice and wild-type controls.
Main Results:
- Wild-type mice showed age-dependent GFAP immunoreactivity, peaking around postnatal day 12 and decreasing with myelination.
- Jimpy mice exhibited intensified GFAP immunoreactivity, increased astrocyte numbers, and enlarged cytoplasm from postnatal day 12 onwards.
- Electron microscopy revealed abundant gliofilaments and glycogen particles in hypertrophied astrocytes of Jimpy mice.
Conclusions:
- Jimpy mice display significant astrocytal hypertrophy and hyperplasia throughout their white matter.
- These findings highlight the profound impact of myelin deficiency on astrocyte morphology and function.