Captopril inhibits capillary degeneration in the early stages of diabetic retinopathy.

Purpose: This study was conducted to examine the effect of angiotensin-converting enzyme (ACE) inhibitors on the development of early stages of diabetic retinopathy.

Methods: Rats were made diabetic by injection of streptozotocin and treated with the ACE inhibitor captopril and the AT1 antagonist losartan. The extent of capillary degeneration and leukostasis in the retina were determined.

Results: Acellular capillaries and pericyte ghosts in the retina of diabetic animals were increased by approximately two-fold after 8 months of diabetes compared with the nondiabetic control, and captopril completely inhibited this capillary degeneration. Captopril and losartan also inhibited hyperglycemia-induced leukostasis at 6 weeks and 1 week in the retinal vasculature, respectively. In cultured retinal endothelial cells, angiotensin II-induced VCAM-1 expression was inhibited by losartan.

Conclusions: Inhibition of the renin-angiotensin system can block retinal capillary degeneration and inflammation in the early stages of diabetic retinopathy.