Abstract: 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 streptozotocin (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 synaptic 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: EM>P/EM> <0.05). Length of the postsynaptic density (PSD) and cleft width were significantly increased (12weeks: EM>P /EM><0.05), and thickness of the PSD was decreased in comparison with that in the control group (12weeks: EM>P /EM><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

Key words: Diabetic retinopathy, Postsynaptic density protein 95, Synaptic parameter, Immunohistochemistory, Image analysis, Rat