糖尿病大鼠视神经病变及发病机理研究

Optic neuropathy in diabetic rats and mechanism thereof

目的研究糖尿病大鼠视神经病变以及视神经血流量和微血管通透性的变化。方法雄性Wistar大鼠20只随机分为对照组和糖尿病组。用链脲霉素按50mg/kg剂量尾静脉一次性注射制备糖尿病模型。3个月后,采用激光多普勒灌注显像仪观察糖尿病视神经血流量的变化;大鼠尾静脉注射1·5%伊文氏蓝溶液(1ml/200g),用分光光度计检测糖尿病大鼠视神经微血管的通透能力,并在光镜和透射电镜下观察糖尿病大鼠视神经变化。结果糖尿病大鼠视神经纤维萎缩,髓鞘明显脱失,突起肿胀,伴有较多的星形胶质细胞增生;视神经内毛细血管内皮细胞细胞器减少,软膜毛细血管可见白细胞聚集并与内皮细胞黏附;视神经血流量(0·68v±0·05v)低于对照组(1·43v±0·58v)(P<0·01);微血管通透性较对照组增加了2·03倍(P<0·01)。结论糖尿病大鼠3个月时可造成明显的视神经病理性改变,其原因可能与视神经血流量减少和视神经微血管通透性增高有关。

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.