L-arginine is the substrate of nitric oxide production which is involved in the regulation of apoptosis and inflammatory processes. The effect of L-arginine after the formation of fatty streaks (FS) is not fully understood in the hypercholesterolemic model and therefore the main objective of this study was to investigate the effect of L-arginine after fatty streaks were developed in the rabbit aorta. Eighteen male rabbits were fed a 1% cholesterol diet for four weeks. One third of the animals were sacrificed randomly to verify fatty streak formation in the aorta (phase I). Then the high cholesterol diet was replaced with a normal diet, and the remaining animals (n=12) were divided into two groups (phase II); group 1 (n=6): normal diet and group 2 (n=6): normal diet plus L-arginine (3% in drinking water). The experiment was continued for a further four weeks. The serum levels of lipids and lipoproteins were increased significantly in phase I (p<0.05), and the fatty streaks score (1±0.44) indicates the formation of lesions in the aorta. In Phase II, no significant differences were observed between the groups for lipids and nitrite concentrations, inducible and endothelial nitric oxide synthase expressions, the number of apoptotic cells, or fatty streak development. These findings show that the administration of 3% L-arginine for four weeks has no beneficial effect in the developed fatty streaks model.
L-arginine; nitric oxide; iNOS; eNOS; apoptosis; hypercholesterolemia
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