Inhibitory effect of losartan, an AT1 angiotensin II receptor antagonist, on increased leucocyte entrapment in retinal microcirculation of diabetic rats

Background: The effectiveness of losartan for the treatment of leucocyte entrapment in the retinal microcirculation of diabetic rats was evaluated quantitatively. Methods: After diabetes was induced by injection of streptozotocin (STZ), the rots were divided into two subgroups. The first subgroup (n = 6), received no medications; the second subgroup (n = 6) was given fresh drinking water supplemented with losartan (5 mg/kg/day) for 4 weeks, Six rats that were not injected with STZ or given medications served as controls. 4 weeks after intervention, leucocyte dynamics in the retina were observed using acridine orange digital fluorography. Leucocyte entrapment in the retina was compared among the three groups. Results: In the untreated diabetic rats, the number of trapped leucocytes (6.1 (SD 1.4) cells/mm(2)) increased significantly compared with control rats (2.8 (1.2) cells/mm(2); p = 0.005) and diabetic rats treated with losartan (3.1 (0.9) cells/mm(2); p = 0.0002). Conclusions: Losartan, an AT1 angiotensin II receptor antagonist, inhibited increased leucocyte entrapment in the diabetic retina. The authors demonstrated that losartan may have therapeutic efficacy in preventing development of diabetic retinopathy. Further clinical studies of the effect of the angiotensin receptor antagonist on preventing development of diabetic retinopathy are needed.