抗氧化剂 N-乙酰半胱氨酸对糖尿病大鼠早期视网膜神经组织的保护作用

摘要

目的：探讨抗氧化剂N‐乙酰半胱氨酸（N‐acetylcysteine ，NAC）对糖尿病大鼠早期视网膜神经组织的保护作用。方法选用健康成年Sprague‐Dawley（SD）雄性大鼠（2月龄）60只，体质量180～220 g。随机分组为正常对照组（CON组，20只）和糖尿病组（DM组，40只）。采用腹腔注射10 g／L的链脲佐菌素（streptozotocin ，STZ）溶液（60 mg／kg）建立糖尿病大鼠模型，血糖≥16．7 mmol／L者视为糖尿病大鼠动物模型成功（32只），CON组注射等量的柠檬酸‐柠檬酸钠缓冲溶液。将糖尿病大鼠模型随机分为糖尿病1月组和糖尿病2月组，每组16只。每只糖尿病模型大鼠左眼设定为糖尿病对照组（D组），右眼设定为NAC治疗组（NAC组）。糖尿病大鼠病程2周时，NAC组玻璃体腔注射4μL （1．6μg／μL）NAC ，其余糖尿病大鼠玻璃体腔注射4μL 0．01 mmol／L的PBS。HE染色观察视网膜外核层厚度变化；透射电镜观察视网膜神经节细胞的超微结构变化；免疫荧光法检测视网膜神经节细胞的数量。结果在不同的时间点上NAC组较D组视网膜外核层厚度增加（P＜0．01）；而NAC组与CON组视网膜外核层厚度没有明显差异（P＞0．05）。透射电镜下NAC组较D组视网膜神经节细胞中细胞器多，细胞质电子密度高，线粒体肿胀较轻；而NAC组与CON组相比视网膜神经节细胞超微结构无明显差异。在不同的时间点上NAC组较D组视网膜神经节细胞数量增加（P＜0．01）；而NAC组与CON组视网膜神经节细胞数量没有明显差异（P＞0．05）。结论抗氧化剂NAC对糖尿病大鼠早期视网膜神经组织有保护作用。%ABSTRACT:Objective To explore the protective effect of the antioxidant N‐acetylcysteine (NAC) on the retinal nerve tissue of early diabetic rats .Methods We randomly divided 60 healthy adult Sprague‐Dawley (SD) rats weighing between 180 g and 220 g into 2 groups:normal control (CON , n=20) and diabetic (DM , n=40) .By intraperitoneal injection of streptozotocin (60 mg/kg) ,the model of diabetic rats was established .The rats were considered diabetic only when they had hyperglycemia (set at ≥16 .7 mmol/L) (32) .The CON group was injected with the same amount of citric acid and sodium citrate buffer solution .After successful model establishment ,the diabetic rats were randomly divided into 1‐month diabetes group and 2‐month diabetes group ,with 16 rats in each group .The left eye of each experimental diabetic rat was set for diabetes control group (D) while the right eye was set as NAC treatment group (NAC) .At 2 weeks of diabetes ,4μL (1 .6μg/μL) of NAC was injected into the vitreous chamber of NAC group and 4μL (0 .01 mmol/L) of PBS was injected into the vitreous chamber of the other diabetic rats .The thickness changes of outer nuclear layer retina was observed by HE ,ultrastructural changes of retinal ganglion cells were observed under the transmission electron microscope ,and the number of retinal ganglion cells was detected by immunofluorescence method .Results At different time points ,retina outer nuclear layer in NAC group was thicker than in D group (P<0 .01) .However ,the NAC group and the CON group did not differ (P>0 .05) .Under the transmission electron microscope ,NAC group had more retinal ganglion cell organelles ,higher electron density of the cytoplasm ,and milder mitochondria swelling than D group .The NAC group did not differ from CON group in the ultrastructure of retinal ganglion cells . NAC group had an increased number of retinal ganglion cells at different time points compared with the D group (P<0 .01) ,but the NAC and CON groups did not differ in the number of retinal ganglion cells (P> 0 .05) .Conclusion The antioxidant N‐acetylcysteine has a protective effect on the retinal nerve tissue of early diabetic rats .