Glutamate effect on synaptic transmission mediates neurotoxicity in dissociated rat hippocampal neurons

In dissociated rat hippocampal neurons, slow bath application (1 ml/min) of glutamate (50 microM) increased both excitatory and inhibitory synaptic activities. This glutamate effect was abolished by tetrodotoxin or cadmium. The constant perfusion (1 h) of glutamate 50 microM was toxic to the neurons. This toxicity was also blocked by TTX. This suggests that unlike the excitotoxicity at a high (mM) concentration, the glutamate toxicity at 50 microM is mediated by its effect on synaptic transmission.