Abstract
Purpose: :
The present study was performed to investigate the early effects of blue light irradiation on photoreceptors in retinal explant cultures.
Methods: :
Murine retinal explant cultures were irradiated with visible blue light (405 nm) with an output power of 1 mW/cm2. Dihydroethidium was used to determine the production of reactive oxygen species. Morphological alterations of photoreceptor outer segments were determined by live imaging microscopy of outer segments using the mitochondrial dye JC-1 and by transmission and scanning electron microscopy for ultrastructural evaluations. Cell death in the retina was assessed using the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay method.
Results: :
Live retinal explants displayed an increase in ROS production, as revealed by increased fluorescent dihydroethidium products in photoreceptor cells after 30 min of blue light exposure. After 3 h of exposure, blue light caused a disorganization of the normally neatly stacked outer segments of living photoreceptors. Ultrastructural analysis revealed breaks in the cell membrane that surrounds the outer segments, especially in the middle section. The outer segments appeared tortuous, and the lamellar structures became disrupted. TUNEL-staining revealed that long-term blue light exposure induced photoreceptor cell death.
Conclusions: :
In vitro blue light irradiation of retinal explants is a suitable model system to investigate early ultrastructural changes and damages that can lead to death of photoreceptor cells.
Keywords: photoreceptors • degenerations/dystrophies • stress response