糖尿病大鼠视网膜突触后致密物蛋白质95的蛋白表达及突触超微结构的改变

Changes of expression of Postsynaptic density protein 95 and synaptic parameters in the diabetic rat retina

目的观察糖尿病不同时期视网膜突触后致密物蛋白质95(PSD95)的蛋白表达水平以及视网膜突触超微结构的变化。方法雄性3月龄SD大鼠56只,随机分为模型组和对照组,分别腹腔内注射链脲佐菌素(STZ)和0.1mol/L枸橼酸-枸橼酸钠缓冲液,于4、8、12周取眼球,入4%多聚甲醛后固定2h,冷冻切片厚20μm,采用免疫组织化学检测PSD95蛋白表达的变化,显微镜观察视网膜全层并摄片,图像分析;透射电镜观察视网膜突触并摄片。结果 PSD95蛋白表达在糖尿病第8周时开始升高,至12周时升高具有显著意义;视网膜内丛状层的突触结构中的突触间隙增大,突触后致密物厚度变薄,突触活性区长度变长。结论 PSD95的蛋白表达水平以及视网膜突触超微结构的改变可能与糖尿病视网膜病变的发展有关。

Objective The purpose of this study is to observe changes of expression of postsynaptic density protein 95 （PSD95） and synaptic parameters in the diabetic rat retina. Methods Fifty-six 3 months old male rats were randomly divided into the streptozotoein （STZ）-treated and control groups in which STZ or equal quantity of the citric acid-sodium citrate buffer was intraperitoneally injected. After 4, 8, and 12 weeks, the eyeballs were removed and immediately immersed in the 4% paraformaldehyde for 2 hours. Horizontal cryostat sections of 20μm thickness were cut. Expression of PSD95 protein was examined by immunohistochemistory, and morphological changes of synaptie parameters were observed under a transmission electron microscope. The staining results were observed under a microscope and analyzed by RS IMAGE software. Results In the STZ-treated group, the expression of PSD95 in the rat retina was significantly increased in comparison with that in the control group （12weeks： P 〈 0.05 ）. Length of the postsynaptic density （PSD） and cleft width were significantly increased （ 12weeks ：P 〈 0. 05 ） , and thickness of the PSD was decreased in comparison with that in the control group （ 12weeks： P 〈 0. 01 ）. Conclusion The changes of expression of PSD95 protein and synaptic parameters in the STZ-induced diabetic rat retina are related with diabetic retinopathy.