细胞凋亡在STZ诱导糖尿病大鼠早期视网膜病变中的作用机制

Mechanism of apoptosis in early diabetic retina induced by STZ in rat

目的观察链脲佐菌素(STZ)诱导的糖尿病大鼠早期视网膜细胞凋亡情况及血管形态变化,分析细胞凋亡在糖尿病早期的作用机制。方法Wistar大鼠随机分为实验组及对照组各28只,实验组一次性腹腔注射1%STZ诱发糖尿病模型,成模后4、8、16、24周行视网膜形态学检测,TUNEL法原位检测凋亡细胞。结果实验组大鼠早期视网膜血管无明显变化,24周时出现内界膜水肿,各层细胞排列不整,视网膜部分血管管径粗细不一。TUNEL阳性细胞最早于发病4周时出现在视网膜神经节细胞(RGCs),数量呈时间信赖性,至24周时涉及到内核层的双极细胞、血管内皮细胞、周细胞等,凋亡指数与对照组相比,差异有统计学意义(P<0.01)。视神经节细胞层的凋亡指数明显高于内核层细胞(P<0.05)。结论糖尿病所致的视网膜凋亡的损伤要远远早于微血管病变的发生,对抗凋亡的发生机制有可能成为预防及治疗糖尿病视网膜病变(DR)的新策略。

Objective Diabetic retinopathy is one of the most devastating ocular complication of diabetes,and it remains the leading cause of blindness up to now. The aims of present study were to explore the cellular apoptosis of retina during the early stage of diabetic rats and the morphological changes of retinal vessels. Methods Diabetic animal model was produced in 28 adult male Wistar rats by intraperitoneal injection of streptozotocin（STZ） , and 0. 1 mol/L sodium citrate were used at the same way in 28 rats as control group. The successful model was identified based on the blood glucose value 〉 16.7 mmol/L 3 days later. At 4,8,16,24 weeks after establishment of model, the rats were killed and eyeballs were enucleated for the retinal pathological examination by HE staining,and the retinal vessel was examined by the ADPase staining under the light microscope. Apoptosis was detected in retina using TUNEL staining. Results The diabetic model was successfully produced in 28 rats received injection of STZ（ 100% ）. The elevation of blood glucose and HbAc level in periphery blood, decline of body weight were determined in model group compared with control group（ P 〈 0.01 ）. Retinal vessels were stiff in shape in diabetic rats. Edema of retinal inner limiting membrane and irregular retinal cells were observed in the 4th week after injection of STZ. The TUNEL positive cells were detected in retinal ganglion cells in 4 weeks and in bipolar cells,vascular endothelial cells and pericytes at 24 weeks of diabetes. The apoptosis index was significantly higher in retina of diabetic rat compared with control rat in different time points（P 〈 0.01 ）. Conclusion These results demonstrate that retinal apoptosis plays a critical role in the early stage of diabetes. The potential therapeuty of inhibiting the retina apoptosis during the pre-diabetic retinopathy might be effective.