Abstract
Purpose :
To compare the retinal degeneration induced by low-dose sodium iodate (25 mg/kg) in old (19-22 month) C57BI/6J mice vs. young mice (3 month).
Methods :
Old C57BI/6J mice were given an intraperitoneal (IP) injection of 1% sodium iodate at 25 mg/kg. The mice were then imaged a week later using optical coherence tomography (OCT) and a confocal scanning laser ophthalmoscope (cSLO). ImageJ with a custom macro was then utilized to quantify outer retinal and retinal pigment epithelium (RPE) thickness in OCT images. After euthanasia, quantitative real-time PCR (qRT-PCR) was performed to analyze gene expression in the neurosensory retina (NSR). Retinal histology was also performed.
Results :
A dose of 25 mg/kg sodium iodate resulted in consistent damage in young mice but more variable damage in old mice. Additionally, cSLO images demonstrated more peripheral speckled hyper/hypo autofluorescence for old mice, whereas young mice had both central and peripheral speckled hyper/hypo autofluorescence. Furthermore, young mice displayed significant outer retinal thinning, while the outer retina in old mice was relatively maintained. However, RPE hypertrophy was more prominent in old mice than young mice. Plastic sections displayed RPE atrophy in both age groups, as well as an abundance of outer retinal tubulations in old mice but not young mice. In young mice, there was also a difference between the damage induced in males compared to females with males displaying more outer retinal thinning.
Conclusions :
Administering a low dose of IP sodium iodate at 25 mg/kg offers an effective model when testing potential therapies for oxidative-stress-related eye diseases such as age-related macular degeneration (AMD), which exhibits RPE/photoreceptor atrophy and outer retinal tubulations. A cross-comparison of the effects of this low-dose model between old and young mice as well as males and females provides insight into how both age and sex play a crucial role in the extent, localization, and morphology of induced damage.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.