Glutamate
Glutamate has numerous functions and is one of the most important neurotransmitters in the neurological system. In excessive amounts, glutamate has a neurotoxic effect in many neurodegenerative diseases such as Parkinson's, Alzheimer's or glaucoma. It is also known that glutamate is involved in the degeneration effects in both high-pressure glaucoma models and normal-pressure models.
NMDA model
To investigate the direct pathological effect of glutamate on the neurons of the retina, we use an established rat degeneration model. In this model, very rapid retinal degeneration is induced by the intraocular injection of N-methyl-D-aspartate (NMDA), a synthetically produced glutamate analogue. NMDA has the advantage over glutamate that it is not broken down as quickly and thus triggers a longer activation of the NMDA receptor.
The research group's analyses focus on the long-term effects after NDMA application. We have already shown that a loss of retinal ganglion cells occurs after just three days and that this is accompanied by the activation of microglia cells. Interestingly, the microglia reaction could be observed not only after three, but even after 14 days, although this is usually an early reaction within the degeneration processes (Kuehn et al. 2017 and 2018). In this model, a still unknown mechanism, which needs to be further investigated in the future, leads to long-term activation of microglia.