[Optic neuropathy in diabetic rat and mechanism thereof].

OBJECTIVE: To observe the diabetic optic neuropathy in diabetic rats, and analyze the relation between the diabetic optic neuropathy and change of blood flow and microvascular permeability of the optic nerve.

METHODS: Twenty male Wistar rats were randomly divided into control and diabetic groups. Diabetic model was induced by the intravenous injection of streptozotocin (50 mg/kg). Three months later blood flow of the optic nerve was measured using laser Doppler perfusion imager. 1.5% Evan's blue was injected into the caudal vein, 1 hour later the rats were killed with their bilateral optic nerves taken out. The permeability of optic nerve was tested by spectrophotometer. The optic nerves are observed with light microscopy and transmission electron microscopy.

RESULTS: Atrophy and demyelination of the optic nerve, proliferation of glial cells, neurite swelling, and decrease of organelles in the endothelial cells in optic nerve capillaries were seen. Leukocytes aggregated and adhered to the endothelial cells of pia-mater capillaries. The blood flow of the optic nerve in the diabetic rats was 0.68 v +/- 0.05 v, significantly lower than that of the control rats (1.43 v +/- 0.58 v, P < 0.01). Whereas, the permeability of the optic nerve of the diabetic rats showed a 2.03-fold increase compared with that of the control rats (P < 0.01).

CONCLUSION: Three-month diabetes induced optic neuropathy may be related to the decrease of blood flow and increase of microvascular permeability.