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Updated: Dec 25, 2025
Müller Glia Cell Activation in a Laser-induced Retinal Degeneration and Regeneration Model in Zebrafish
Published on: October 27, 2017
Coordinated Intervention of Microglial and Müller Cells in Light-Induced Retinal Degeneration
Purpose:
To analyze the role of microglial and Müller cells in the formation of rings of photoreceptor degeneration caused by phototoxicity.
Methods:
Two-month-old Sprague-Dawley rats were exposed to light and processed 1, 2, or 3 months later. Retinas were dissected as whole-mounts, immunodetected for microglial cells, Müller cells, and S- and L/M-cones and analyzed using fluorescence, thunder imaging, and confocal microscopy. Cone populations were automatically counted and isodensity maps constructed to document cone topography.
Results:
Phototoxicity causes a significant progressive loss of S- and L/M-cones of up to 68% and 44%, respectively, at 3 months after light exposure (ALE). One month ALE, we observed rings of cone degeneration in the photosensitive area of the superior retina. Two and 3 months ALE, these rings had extended to the central and inferior retina. Within the rings of cone degeneration, there were degenerating cones, often activated microglial cells, and numerous radially oriented processes of Müller cells that showed increased expression of intermediate filaments. Between 1 and 3 months ALE, the rings coalesced, and at the same time the microglial cells resumed a mosaic-like distribution, and there was a decrease of Müller cell gliosis at the areas devoid of cones.
Conclusions:
Light-induced photoreceptor degeneration proceeds with rings of cone degeneration, as observed in inherited retinal degenerations in which cone death is secondary to rod degeneration. The spatiotemporal relationship of cone death microglial cell activation and Müller cell gliosis within the rings of cone degeneration suggests that, although both glial cells are involved in the formation of the rings, they may have coordinated actions and, while microglial cells may be more involved in photoreceptor phagocytosis, Müller cells may be more involved in cone and microglial cell migration, retinal remodeling and glial seal formation.
Insights
Phototoxicity causes progressive cone loss in rings. Microglial and Müller cells coordinate in this degeneration, with Müller cells potentially guiding migration and remodeling.
Area of Science:
- Ophthalmology
- Neuroscience
- Cell Biology
Background:
- Phototoxicity induces photoreceptor degeneration, a process relevant to inherited retinal diseases.
- Microglial cells and Müller cells are glial components of the retina with roles in injury response.
Purpose of the Study:
- To investigate the specific roles of microglial cells and Müller cells in forming rings of photoreceptor degeneration following phototoxicity.
Main Methods:
- Sprague-Dawley rats were exposed to light, and retinas were analyzed at 1, 2, and 3 months post-exposure.
- Immunodetection of microglial cells, Müller cells, and cone photoreceptors (S- and L/M-cones) was performed.
- Confocal microscopy, thunder imaging, and automated cone counting were used to map degeneration patterns.
Main Results:
- Phototoxicity led to significant S- and L/M-cone loss (up to 68% and 44%).
- Rings of cone degeneration, accompanied by activated microglial cells and Müller cell processes, were observed and expanded over time.
- Coalescing rings correlated with microglial repopulation and reduced Müller cell gliosis in cell-depleted areas.
Conclusions:
- Light-induced degeneration forms rings, similar to some inherited retinal degenerations.
- Microglial and Müller cells are involved in ring formation, suggesting coordinated actions.
- Microglial cells may be involved in photoreceptor phagocytosis, while Müller cells might aid in cell migration, retinal remodeling, and glial seal formation.
