Hypercholesterolemia induces leukocyte entrapment in the retinal microcirculation of rats

Purpose. To evaluate leukocyte dynamics in the retinal microcirculation of hypercholesterolemic rats in vivo using acridine orange digital fluorograph y. Methods. 18 male pigmented rats were divided into 3 groups according to the ir diet; (A) control diet (0.1% cholesterol) for 8 weeks, (B) control diet for an initial 4 weeks followed by a high-cholesterol (HC) diet (5% cholest erol) for another 4 weeks and (C) HC diet for 8 weeks. Leukocyte dynamics w ere observed with acridine orange digital fluorography. The diameter of maj or retinal vessels and the number of leukocytes trapped in the retina were evaluated quantitatively. Results. Both groups B and C showed approximately 14-fold higher serum chol esterol levels than in group A. The diameters of retinal arteries and veins were not significantly different among the three groups. Also, no rolling leukocytes were observed in any of the groups. In the retinal microcirculat ion at 30 minutes after acridine orange injection, the density of trapped l eukocytes in both groups B and C was significantly greater than in group A (23.19 +/-2.13, 28.56 +/-1.96 and 13.67 +/-1.45 cells/mm(2), respectively, p<0.01). Furthermore, group C exhibited a significantly greater number of t rapped leukocytes than in group B (p<0.01). Conclusion. Enhanced leukocyte entrapment in the retinal microcirculation w as induced in the early stage of hypercholesterolemia. Entrapment was incre ased as the period of hypercholesterolemia was prolonged. Leukocyte accumul ation in the retina may be an early vascular dysfunction leading to arterio sclerosis in hypercholesterolemia.