Effect of flaxseed on choroids sclera complex thickness and on LDL oxidation in the sclera, choroid and retina of diet-induced hypercholesterolaemic rabbits.

Key Findings:

Oxidised LDL leading to elevated levels of chemotactic and adhesion molecules that attract macrophages. Inflammatory cytokines and other factors are released from these cells and can worsen the age related macular degeneration (AMD). AMD is also increased in situations of hypercholesterolaemia. Here, hypercholesterolaemic rabbits were supplemented with flaxseed to investigate its effect on LDL oxidation in the sclera, choroid and retina. Oxidised LDL stimulate the endothelial cells of the vessels to increase the expression of vascular adhesion molecules which can increase the inflammatory process. Increases in serum TC and LDL C concentrations were noted in rabbits fed a hypercholesterolaemic diet, and in those fed a hypercholesterolaemic diet enriched with flaxseed. The former group showed cholesterol concentrations that were eight times the initial level at the end of the study. Flax fed animals had significant lower concentrations TC and LDL C concentrations than control. A significant reduction of oxidised LDL expression and lower levels of histiocytes in the choroids sclera complex of flax fed rabbits when compared with cfontrol rabbits, was reported. Further studies are required to demonstrate whether flaxseed has other positive effects in AMD.

ABSTRACT:

The aim of the present study was to evaluate the effect of flaxseed on choroids sclera complex thickness and on LDL oxidation in the sclera, choroid and retina of diet induced hypercholesterolaemic rabbits. New Zealand male albino rabbits (n 21) were divided into two groups: group 1 (G1; n 11), fed a hypercholesterolaemic diet, and group 2 (G2; n 10), fed a hypercholesterolaemic diet enriched with flaxseed flour. The serum concentrations of total cholesterol (TC), LDL cholesterol (LDL-C), HDL cholesterol, TAG and fasting blood glucose were determined at the start of the experiment and on the day of killing (8th week). Choroid and sclera samples were subjected to haematoxylin eosin (HE) staining and histomorphometric and immunohistochemical analyses with the anti-oxidised LDL antibody. Sensory retina samples were subjected to an immunohisto chemical analysis with the primary monoclonal nitrotyrosine antibody. At the end of the experiment, a significant increase was observed in TC and LDL C concentrations in G1 rabbits when compared with G2 rabbits (P=0·008 and P=0·02, respectively). HE staining revealed a significant increase in choroids sclera complex thickness in G1 rabbits when compared with G2 rabbits. Immunohistochemical analysis of choroid and sclera samples with the antioxidized LDL marker revealed a significant increase in immunoreactivity in G1 rabbits when G2 rabbits (P< 0·001). Immunohistochemical analysis of choroid and sclera samples with the anti-oxidised LDL marker revealed a significant increase in immunoreactivity in G1 rabbits when compared with G2 rabbits (P< 0·001). Immunohistochemical analysis of sensory retina samples with the anti-nitrotyrosine marker revealed a significant increase in immunoreactivity in G1 rabbits when compared with G2 rabbits (P= 0·002). Flaxseed reduced the choroids sclera complex thickness of diet induced hypercholesterolaemic rabbits and the expression of oxidised LDL in the choroids sclera complex as well as the expression of nitrotyrosine in the sensory retina. (Author’s abstract)