Effects of topical nipradilol on retinal microcirculation of early diabetic retinopathy

Abstract

Abstract: : Purpose:To study the effect of topical nipradilol, an α–ß blocker as well as an nitric oxide (NO) donor ophthalmic agent for glaucoma, on the retinal microcirculation of diabetic animal models. Methods:Seven diabetic Brown–Norway rats were made by a single intravenous injection of streptozocin (STZ) (65 mg/kg). Diabetes was confirmed by a blood glucose level above 350 mg/dl 48 hrs after injection. The rats received 1% nipradilol solution on the right eyes and nipradilol–free base solution on the left eyes 3 times per day for 3 weeks. Three weeks later, the retinal microcirculation was evaluated by acridine orange leukocyte digital fluorography using laser scanning ophthalmoscopy. Dye–stained leukocytes trapped in the retina (retinal leukostasis) were counted in the area around the optic disc (10 disc diameter) and compared between the right and the left eyes. Results:The mean retinal leukostasis counts in the nipradilol–treated eyes(19±15 cells) were significantly lower than that in non–treated eyes (49±19 cells).(p<0.0008) Conclusions:Topical nipradilol significantly reduced the retinal leukostasis in the retinal microcirculations of early diabetic retinopathy. Nipradilol may be the possible prophylactic agent of early diabetic retinopathy through its NO–donor effects on microcirculation.

Keywords: nitric oxide • diabetic retinopathy • cell adhesions/cell junctions