Methods: Retinas were obtained from Sprague-Dawley (SD) rats at the 14^th postnatal day. The cells were maintained in B27-supplemented medium supplemented with 2% fetal bovine serum (FBS),1 mMglutamine and antibiotics. The culture media were with or without2mMglutamate, 200μM AIP were added to the medium after2mMglutamate treatment for 24 hours. Expression of RGCs markers thy-1 and axon marker neuronal class III β-tubulin and neurofilament light chain (NFL) were studied by immunohistochemistry, and numbers of both surviving RGCs and their axons were quantified using a microscope.

Results: We successfully established an ex vivo model of rats’ retinal explants of RGCs. The RGCs shrank the third day of culture, and were even much smaller and fewer the fifth day (P<0.05). The axons of RGCs around the papilla were greatest and in good order toward papilla the first day of culture. Their number reduced and they twisted the third day, and the fifth day, their number was significantly reduced and twisted (P<0.05). The expression of both neuronal class III β-tubulin and neurofilament light chain (NFL) were reduced after treatment with glutamate while the AIP relieved the damage caused by glutamate.

Conclusion: Our study demonstrated that both the AIP has the neuroprotective effect of preventing RGCs from glutamate-caused injury in a retinal explant model. This study also showed a significant change in RGCs death and axonal loss with time in ex vivo model of retinal explants, which is an essential characteristic for cell death and survival study. To our knowledge, the rat retinal explants of RGCs model we discuss is a novel one for the study of RGCs neuroprotection.

Key words：RGCs, glutamate, retinal explants, neuroprotection