BACKGROUND: Members of the immunoglobulin superfamily of endothelial adhesion 
molecules, vascular cell adhesion molecule (VCAM-1) and intercellular cell 
adhesion molecule (ICAM-1), participate in leukocyte adhesion to the endothelium 
and play an important role in all stages of atherosclerosis. The aim of the 
study was to examine the expression of VCAM-1 and ICAM-1 in the aorta of rats at 
the early stages of atherosclerosis and the correlation with their plasma 
concentrations.
MATERIALS AND METHODS: Male rats (n=44), 10 weeks of age, were divided in 4 
groups. Groups A and C (n=12) were fed with rich cholesterol diet for 12 and 16 
weeks, respectively. Group B (regression group, n=12) was fed for the first 12 
weeks with rich cholesterol diet and for another 4 weeks with normal diet. Group 
D (control group, n=8) was fed with normal diet for 12 weeks. We measured the 
serum lipid profile, the concentration of soluble ICAM-1 and the 
immunohistochemical expression of ICAM-1 and VCAM-1 in the endothelium, media 
and vasa vasorum of the aorta.
RESULTS: There were significant differences (p<0.05) in the expression of ICAM-1 
between group C (maximum time of rich cholesterol diet) and all other groups in 
the 3 groups of the aorta studied. There was regression of the expression of 
ICAM-1 in group B and significant differences (p<0.05) between group B and all 
the other groups, except group D in the expression of ICAM-1. There were no 
significant differences in the expression of VCAM-1 between any groups. The 
serum concentration of soluble ICAM-1 positively correlated with the expression 
of the molecule in the vasa vasorum (r=0.35, p<0.05) and fibroblasts/smooth 
muscular cells (r=0.34, p<0.05) of the aorta.
CONCLUSION: A cholesterol diet plays a role in the expression of ICAM-1 but not 
in that of VCAM-1 in the rat aorta. The expression of ICAM-1 in the aorta 
regresses after the withdrawal of a cholesterol-rich diet. Soluble ICAM-1 is a 
reliable measure of ICAM-1 expression in the aorta, vasa vasorum and 
fibroblasts/smooth muscle cells.