Influence of metabolic control on the blood-retinal barrier in streptozocin diabetic rats

One hundred and eight male Sprague-Dawley rats weighing 160-225 g were examined with vitreous fluorophotometry (VF). Fifty-five rats were made diabetic with streptozocin (43 with 65 mg/kg and 12 with 90 mg/kg); 53 nondiabetic rats served as controls. Fluorescein (7 mg/kg) was injected IV and VF was performed 60 min later. The diabetic rats had an abnormal blood-retinal barrier (BRB) after 4-7 days duration. The difference between the diabetic and non-diabetic rats was persistent up to 35 days (P < 0.02-0.001). The diabetic rats treated with 90 mg/kg streptozotocin had a more severe diabetes and a higher treated with 65 mg/kg (P < 0.05). The BRB function was normalized in 18 rats treated for 6-7 days with 5-6 IU long-acting insulin (P < 0.02). The results imply that streptozocin-diabetic rats have an abnormal BRB and that this abnormality seems to be related to the diabetic state and to be reversible after insulin treatment.