Age dependent sensitivity of the rat retina to the excitotoxic action of n-methyl-d-aspartate

We have found that the rat retina can be isolated atraumatically and incubated ex vivo for up to 24 h without showing signs of histological deterioration, and that retinas from adult or aged rats can be isolated as successfully as those from immature rats. In the present study we used this preparation to show that rat retinal neurones at post-natal day zero (PND 0) are relatively insensitive to the excitotoxic action of the glutamate agonist, N-methyl-D-aspartate (NMDA), then gradually show increasing sensitivity that peaks at about PND 9 and declines from PND 15-30 after which it remains at a low level up to the last time point studied (10 months of age). This is consistent with other developmental NMDA receptor data and underscores the need for caution in using immature in vitro central; nervous system (CNS) tissue preparations as a basis for interpreting the role of NMDA receptors in adult neurological diseases.