Morphological and Functional Alterations in the Mouse Retina After Sodium Fluorescein Administration

Sodium fluorescein (SF) is commonly used to observe retinal and choroidal vasculature for clinical or scientific purposes, but few studies focused on concentration of fluorescein, volume injected, and rate of injection in animal experiments. The aim of this study was to investigate the effect of SF on structure and function of the retina in mice.

C57BL/6J mice were injected intraperitoneally with 0.7% saline solution, 5.0% SF, and 10.0% SF, morphological, functional, and molecular changes of the retina were evaluated by fluorescein angiography, electroretinography (ERG), histology, TUNEL assay, immunohistochemistry (IHC), and Western blot.

Fluorescein intensity of 10.0% SF-treated mice was higher than 5.0% SF-treated mice. ERG showed early reduction of retinal function, followed progressive restoration of ERG responses. Histology revealed irregular or disorganized features of outer retina after SF administration. TUNEL assay revealed apoptosis in the outer nuclear layer. IHC demonstrated comparable expressions of Rhodopsin, M-opsin, and S-opsin in all groups, but the 10.0% SF-treated mice exhibited the higher immunoreactivity of glial fibrillary acidic protein (GFAP). Molecular analysis showed increased expressions of BAX, NRF2, and HO1, and decreased expression of BCL2 in the retina and retinal pigment epithelial (RPE).

Administration of a higher dose of SF could induce some abnormal alterations in the retina, which were not easily distinguishable from pathological changes in the development of ocular diseases in animal models.

The SF-induced retinal changes that are similar with some histopathological features could affect the authenticity of experimental data, which optimizing the dose of SF should not be ignored in experimental research on mice.