Abstract
Purpose :
To test whether tamoxifen is retina-protective in male mice in the sodium iodate model.
Methods :
Male C57Bl/6J mice were given oral tamoxifen (in the diet) or normal diet, then given an intraperitoneal (IP) injection of sodium iodate at 25 mg/kg. The mice were imaged a week later using optical coherence tomography (OCT). ImageJ with a custom macro was utilized to quantify OCT images by measuring the distance between the top of the inner nuclear layer (INL) and Bruch’s membrane. Electroretinogram (ERG) measurements were also taken one week post-injection. After euthanasia, quantitative real-time PCR (qRT-PCR) was performed.
Results :
Tamoxifen administration resulted in photoreceptor protection in the sodium iodate model. There was less photoreceptor layer thinning in OCT images of tamoxifen treated mice. qPCR revealed, in the tamoxifen treated group, less upregulation of antioxidant and complement factor 3 mRNAs, and less reduction in the rhodopsin and short wave cone opsin mRNAs. Furthermore, ERG results demonstrated preservation of photoreceptor function for the tamoxifen treated group. Cone function was better protected than that of rods.
Conclusions :
Tamoxifen provided structural and functional protection to photoreceptors against sodium iodate. These neuroprotective effects suggest that estrogen-receptor agonism may be retina-protective. The fact that cones are particularly protected is intriguing given their importance for visual function and their survival until the late stages of retinitis pigmentosa. Further investigation of this pathway could lead to new photoreceptor-protective therapeutics.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.