Optic nerve lesions in diabetic rats: blood flow to the optic nerve, permeability of micro blood vessels and histopathology.

Abstract

To study optic nerve lesions, changes in blood flow to the optic nerve, and permeability of micro blood vessels and histopathology in diabetic rats. Male Wistar rats (n=20) were randomly divided into control and diabetic groups. The diabetic model was prepared by a single injection of streptozotocin (50mg/kg) into the caudal vein. Three months later, laser Doppler perfusion imaging was used to observe the changes in blood flow to the optic nerve. Each rat was injected with 15g/L Evans blue (5µL/g). The permeability of microvessels in diabetic optic nerves was measured by spectrophotometry. Optic nerves were observed by light and transmission electron microscopy. Diabetic rats had atrophic optic nerve fibers with neurite swelling, loss of myelin, and a greater-than-normal proliferation of astrocytes, occurring within 3 months of induction of diabetes. Blood flow to the optic nerve was lower in diabetic rats than in controls. Microvessel permeability in diabetic rats increased 2.03-fold compared to controls. Diabetic rats develop significant pathological changes in the optic nerve, reduced blood flow to the optic nerve and increase microvessel permeability.