Hypoxia-induced retinal ganglion cell damage through activation of AMPA receptors and the neuroprotective effects of DNQX

Abstract Hypoxia-induced glutamate accumulation in neural tissues results in damage to neurons through excitotoxic mechanisms via activation of glutamate receptors (GluRs). Here we examine whether hypoxia in the developing retina would cause activation of the ionotropic α-amino-3-hydroxy-5-methylisoxazole-4-propioate (AMPA) GluRs and increase in Ca 2+ influx into retinal ganglion cells (RGCs) that might ultimately lead to their death. Neonatal Wistar rats were subjected to hypoxia for 2h and then sacrificed at various time points after the exposure together with normal age matched control rats. Primary cultures of RGCs were also prepared and subjected to hypoxia. Expression of AMPA glutamate receptor (GluR) 1–4 was examined in the retina. Additionally, expression of GluRs, intracellular Ca 2+ influx, reactive oxygen species (ROS) generation and cell death were investigated in cultured RGCs. GluR1-4 mRNA and protein expression showed a significant increase ( P in vivo and in vitro . Cells expressing GluR1-4 in the retina were identified as RGCs by double immunofluorescence labeling with Thy1.1. Increased intracellular Ca 2+ in cultured RGCs following hypoxic exposure was reduced ( P 2+ accumulation and ROS generation. The involvement of AMPA receptors in damaging the RGCs is evidenced by suppression of intracellular Ca 2+ influx by DNQX which also decreased ROS generation and cell death by 50%.