Effect of Chronic Alcohol Feeding on the Size of Choroidal Neovascular Complex in Rats

Abstract

Purpose: : To investigate the effect of chronic and heavy alcohol consumption on the pathology of choroidal neovascularization (CNV).

Methods: : Male Brown Norway rats (4–6 weeks old) were divided into two groups. Control group (gp1) was fed regular diet and water. Alcohol fed (gp 2) received 8 g/kg alcohol and a regular diet. The animals in both groups were sacrificed after 14 weeks. The eyes were enucleated to separate choroids. Choroidal homogenate was used to perform enzyme assay for rates of fatty acid ethyl ester synthesis. Also Paraffin embedded sections of the alcohol fed and control rat eyes were used for immunostaining for FAEES with rabbit anti–rat FAEES. Experimental CNV was induced on day 88 of feeding by laser photocoagulation (using the krypton red laser) in both groups. Four laser spots were placed in each eye. The animals were sacrificed on day 98, their eyes enucleated and RPE–choroidal –scleral flat mounts were stained with an anti–elastin (CY3 conjugated) antibody. The incidence and size of the CNV was determined by confocal microcopy. The CNV complex size was measured (µ) using Image Pro–Plus software. FAEES was purified from rat choroids. Western blot analysis was done for the expression of cyclin E and cyclin E/CDK 2 proteins.

Results: : There was a 30% increase in the CNV complex size (n=120 laser spots/group) in alcohol fed rats compared to control rats. The incidence of CNV in each group was 92%. We also observed three fold increase in the expression cyclin E and cyclin E/CDK 2 in the choroid of alcohol fed rats compared to control rats. A 4.0 fold increase in FAEES activity was observed in the choroid of alcohol fed rats compared to controls. However, no significant increase in FAEES activity was observed in the cornea, iris & ciliary body, lens and retina. Histologic sections of the eye of alcohol fed rat showed increased staining for FAEES compared to control rats.

Conclusions: : Our results suggest that heavy and chronic consumption of alcohol enhances the CNV complex size by increasing the expression of cell cycle proteins.

Keywords: age-related macular degeneration • neovascularization • retina