AMPA prevents glutamate-induced neurotoxicity and apoptosis in cultured cerebellar granule cell neurons.
Exposure of cultured cerebellar neurons to alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) in the presence of aniracetam protects all of the vulnerable neurons against the excitotoxic actions of glutamate acting on N-methyl-D-aspartate receptors. The protective effect of AMPA was both time- and concentration-dependent. Aniracetam alone did not protect the neurons against the excitotoxic effects of glutamate. Pretreatment of cerebellar neurons with the AMPA antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione blocked the neuroprotective effect mediated by AMPA indicating that the neuroprotective effect is mediated specifically by AMPA receptors. An excitotoxic concentration of glutamate, which killed between 60-80% of granule cell neurons on day 8 in vitro, mediated its toxic effect via a time-dependent apoptotic pathway. Pretreatment of cerebellar granule cell neurons with AMPA (500 microM) completely blocked glutamate-mediated apoptosis. Our results suggest that AMPA receptors may play an important role in neuronal survival.