Spatiotemporal expression of postsynaptic density 95 in rat retina after optic nerve injury

Postsynaptic density protein 95 (PSD95) contains three PSD95/Drosophilia disk large/ZO-1[PDZ] homology domains and links neuronal nitric oxide synthase (nNOS) with the N-methyl-D: -aspartic acid receptor. Previous studies showed that the assembly of PSD95/nNOS signaling played an important role in rat ischemic brain injury. In this study, we aimed to elucidate the changes of PSD95 expression and location in retina after optic nerve crush. The optic nerve injury model of rats was created by crushing optic nerve at 2 mm retrobulbarly. Real-time PCR and Western blot analysis were used to analyze mRNA and protein expression of PSD95. The spatial distribution of PSD95 were evaluated by immunohistochemistry. Immunofluorescence was performed to observe the co-localization of PSD95. The PSD95 expression diminished at 1 day and elevated and peaked on the 7th day of post-injury. The mRNA and protein levels of PSD95 underwent the similar change. The association of PSD95 and rhodopsin was detected by immunofluorescence double staining. The injury-induced expression of PSD95 was physically co-existed with active caspase-3 (apoptotic marker) and nNOS. The spatiotemporal changes of PSD95 expression suggests that this protein likely to play a role in the degenerative process of never cells induced by optic nerve injury in the retina.