方法：健康成年雄性SD大鼠30只，按照随机分配的原则分为正常对照组(CON组，n=10)，糖尿病组(DM组，n=20)。DM组禁食12h后，按照60mg/kg体质量剂量一次性左下腹腔注射1%链脲佐菌素(STZ)溶液，CON组注入等量的柠檬酸缓冲溶液。用药72h后，鼠尾静脉取血检测血糖，≥16.7mmol/L者定为糖尿病模型动物。成模大鼠随机分为糖尿病对照组(D组)和NAC治疗组(N组)。模型建立后，N组大鼠每周通过玻璃体腔注射4μL 1.6μg/μL的NAC，CON组、D组大鼠则给予玻璃体腔注射4μL 0.01mmol/L的磷酸缓冲盐溶液(pbs)不限饮食水，分组喂养。每周记录各组大鼠体质量及血糖。糖尿病成模后2mo，处死实验动物，通过HE染色法，检测各组大鼠视网膜内核层厚度； 通过免疫荧光法，检测各组大鼠视网膜神经节细胞数量及视网膜中色素上皮衍生因子(PEDF)水平。

结果：N组视网膜内核层厚度较D组厚度增加(P<0.01)，与CON组厚度无差异(P>0.05)。与CON组相比，D组视网膜神经节细胞数量减少(P<0.01)，N组视网膜神经节细胞略减少(P>0.05)。D组视网膜神经节细胞较N组减少(P<0.01)。与CON组相比，D组PEDF表达下降(P<0.01)，N组PEDF表达略下降(P>0.05)。D组PEDF表达较N组下降(P<0.01)。

结论：抗氧化剂NAC对早期糖尿病大鼠视网膜组织有保护作用的机制可能是通过上调视网膜中PEDF水平。

METHODS: Thirty healthy adult male SD rats were randomly assigned to the normal control group(CON group, n=10)and the diabetes group(DM group, n=20). After fasting for 12h, the DM group was injected with 1% streptozotocin(STZ)solution, according to 60mg/kg disposable left lower abdominal injection. After 72h, blood was taken from the rat tail vein to detect blood glucose, diabetic model animals were defined as ≥16.7mmol/L. Model rats were randomly divided into diabetes control group(group D)and NAC treatment group(group N). After the model was established, N group of rats were injected with 4μL 1.6μg/μL NAC through the vitreous cavity every week. Rats in CON group and D group were injected with 4μL 0.01mmol/L phosphate buffer saline. All the rats no diet water, group feeding. Body mass and blood glucose were recorded weekly. After the diabetes was modeled, 2mo killed the experimental animals. The thickness of the inner layer of the retina of rats in each group was determined by HE staining. The number of retinal ganglion cells and the level of pigment epithelial derived factor in the retina were measured by immunofluorescence.

RESULTS: The thickness of retinal kernel layer increased in group N compared with group D(P<0.01), and there was no difference between group CON and group(P>0.05). Compared with CON group, the number of retinal ganglion cells decreased in group D(P<0.01), and decreased slightly in group N(P>0.05). Retinal ganglion cells decreased in group D compared with group N(P<0.01). Compared with CON group, PEDF expression decreased in group D(P<0.01), and decreased slightly in group N(P>0.05). The expression of PEDF in group D decreased compared with group N(P<0.01).

CONCLUSION: The protective effect of antioxidant NAC on retinal tissue in early diabetic rats may be due to the up-regulation of PEDF levels in the retina.