目的：初步探讨大豆异黄酮对糖尿病大鼠视网膜神经节细胞(RGCs)损伤的保护作用及相关机制。

方法：取4-6周龄雄性SD大鼠80只80眼，随机分为对照组、糖尿病组、大豆异黄酮低剂量处理组和大豆异黄酮高剂量处理组，每组20只。其中，对照组给予普通饲料喂养，糖尿病组和大豆异黄酮低剂量处理组和高剂量处理组大鼠给予高脂饲料喂养。喂养4 wk后，糖尿病组、大豆异黄酮低剂量组和高剂量处理组大鼠按照50 mg/kg剂量的链尿佐菌素进行腹腔注射，建立糖尿病模型，对照组给予相同剂量的柠檬酸钠缓冲液。大豆异黄酮低剂量组是对糖尿病模型大鼠每天给予360 mg/kg大豆异黄酮灌胃，高剂量组每天给予540 mg/kg大豆异黄酮灌胃，对照组及糖尿病组每天给予等量的纯水灌胃。分别在处理4、8 wk时，进行体质量和血糖水平的测定。8 wk时摘取眼球，剥离视网膜。通过免疫组织化学染色和蛋白质印迹技术检测各组大鼠RGCs的数量，采用组织化学手段检测大鼠视网膜组织超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量。

结果：与糖尿病大鼠相比，大豆异黄酮高剂量组处理8 wk时，可以降低糖尿病大鼠的血糖至8.9±1.23 mmol/L，提高大鼠视网膜内SOD活性至849.93±63.71 U/mgprot，降低MDA含量至45.77±0.59 nmol/mgprot，RGCs的数量与对照组接近，增多至76±1 cells/mm²(均P<0.05)。

结论：大豆异黄酮处理可以降低糖尿病大鼠视网膜内的氧化应激反应，发挥对RGCs的保护作用。

METHODS: Totally 80 male SD rats(80 eyes), aged 4-6 weeks, were randomly divided into four groups(n=20 per group): a control group, a diabetic model group, a low-dose soy isoflavone treatment group, and a high-dose soy isoflavone treatment group. Among them, the control group was fed normal chow, while the diabetic group, soy isoflavone low-dose-treated group, and soy isoflavone high-dose-treated group were fed high-fat chow. After a feeding period of 4 wk, rats in the diabetic group, as well as those in the soy isoflavone low-dose and high-dose treatment groups, were injected intraperitoneally with streptozotocin(STZ)at a dose of 50 mg/kg to establish a diabetic model. Rats in the control group received an equivalent volume of sodium citrate buffer acid. The soy isoflavone low-dose-treated group was administered 360 mg/kg of soy isoflavones daily via gavage, while the soy isoflavone high-dose-treated group received 540 mg/kg of soy isoflavones daily via gavage. Both the control group and the diabetic group were given an equal amount of purified water daily via gavage. Body weight and blood glucose levels were measured at 4 and 8 wk post-gavage treatment. The eyes were extracted and the retinas were dissected at 8 wk following the gavage treatment. The number of RGCs in each group was determined using immunochemical tissue staining and protein blotting techniques, while the superoxide dismutase(SOD)activity and malondialdehyde(MDA)content of the rat retinal tissue were measured through histochemical methods.

RESULTS: Compared with diabetic rats, treatment with high-dose soy isoflavones for 8 wk resulted in a reduction of blood glucose to 8.9±1.23 mmol/L, an increase in intraretinal SOD activity to 849.93±63.71 U/mgprot, a decrease in MDA content to 45.77±0.59 nmol/mgprot, and an increase in the number of RGCs to 76±1 cells/mm², which is comparable to the control group's data(all P<0.05).

CONCLUSION: Soy isoflavones can reduce retinal oxidative stress in diabetic rats and protect RGCs.