Abstract
Purpose: :
Zinc supplementation is one of the most widely used preventative strategies for choroidal neovascularisation (CNV) in age-related macular degeneration (AMD). However, the mechanism with which zinc exerts its effect is largely unknown. In this study a mutant mouse model for early bilateral spontaneous CNV (JR5558) was supplemented with zinc to examine how this treatment affects the condition.
Methods: :
A group of JR5558 mice supplemented with zinc in drinking water from birth were compared with a control group with regular lab water. In the zinc group, the mothers were placed on 10 mg/L zinc carbonate and 0.25mg/L copper chloride on the day of birth to allow zinc supplementation of the litter through breast milk. The copper was added to avoid zinc induced copper deficiency. Following weaning the pups continued to receive zinc supplemented water. CNV was assessed by fluorescent angiography (FA) on day 25, a time point at which all control mice show definitive CNV. The images were analysed for number, size and degree of leakage of lesion using Image J software.
Results: :
Following the analysis of 6 control eyes and 12 eyes in the zinc group, the number of lesions was shown to be reduced in the zinc group by ~50% (p <0.01). While, the sizes of lesions at early AF images were larger by ~20% (p < 0.07) and more defined in the zinc group the leakage of the CNV was reduced by ~20% (p<0.07) compared to the controls.
Conclusions: :
Zinc supplementation appeared to cause a reduction in both the number and leakage of CNV lesions in our model system. Further analysis of morphological features by light, fluorescent and electron microscopy and changes at the molecular level will help to understand the mechanisms involved in the beneficial effects of zinc supplementation in CNV. It is intriguing to speculate whether a combination of anti-VEGF-A therapy with zinc supplementation might be the way forward to increase efficacy of treatment for CNV associated with AMD.
Keywords: age-related macular degeneration • choroid: neovascularization • antioxidants