Abstract
Purpose :
The purpose of the study is to test the hypothesis that zeaxanthin supplementation would prevent on oxidative damage and pathology in the retinal pigment epithelium (RPE) in Sod2flox/flox-VMD2-cre mice. RPE-specific deletion of Sod2 (manganese superoxide dismutase) in this mice model causes signs of atrophy characteristic of dry age-related macular degeneration (AMD).
Methods :
Zeaxanthin beadlets were dissolved in sterile water (1gm/kg body weight). For the experimental group (n=10), diluted Zeaxanthin beadlets were delivered by daily gavage to mice starting at one month of age and extending up to five months of age. A group of mice (n=8) of same ages not receiving any supplementation served as a control. Zeaxanthin retention in the retina/RPE and liver was quantified one month following supplementation. Retinal function was evaluated by electroretinogram (ERG) and optical coherence tomography (OCT). Quantitative real time PCR of antioxidant genes was used to measure the levels of antioxidant genes after one month and four months of zeaxanthin supplementation.
Results :
Zeaxanthin supplementation led to 5-fold increases in zeaxanthin in the retina/RPE (12.8ng/gram tissue) and 12-fold increases in liver (205ng/ gram tissue) compared to control mice. There was a significant decrease in a-wave and b-wave in both control and zeaxanthin-treated mice control mice by five months of age. However, we saw improved c-wave ERG amplitude (28%; p<0.01) and thicker RPE (p<0.01) in experimental mice than control mice suggesting improved function of RPE. After one month of zeaxanthin supplementation, we did not find any changes in antioxidant gene (CAT, GSTM1, HO1, NQO1, and SQSTM1) expression in the RPE/choroid, but after 4 months of supplementation there was a significant increase in expression of the same genes.
Conclusions :
We conclude that daily supplementation of zeaxanthin leads to increased accumulation of this carotenoid in the retina/RPE, induction of antioxidant enzymes, and improved structure and function of the RPE.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.