Immunohistochemical detection of blood-retinal barrier breakdown in streptozotocin-diabetic rats.

Immunohistochemical staining for albumin (69 kDa) and fibrinogen (340 kDa), as markers of blood-retinal barrier (BRB) breakdown of the retinas of streptozotocin-treated diabetic rats, was performed. The number of rats with BRB breakdown was three of nine at 6 months, four of seven at 12 months, and three of three at 18 months. Extravasation of albumin from the retinal vessels was detected in the retinas of rats maintained for 6, 12, and 18 months, while extravasation of fibrinogen was detected only in the retinas of rats maintained for 18 months. These findings suggested that the duration of diabetes has an influence on BRB breakdown and that each substance in the blood starts to permeate the vascular wall individually.