Cell experiment:

CNQX is applied by injecting a bolus into the input line of the chamber over 60 s using a motorized syringe pump. In a subpopulation of neurons, CNQX is bath applied for 5 min. Control injections of physiological saline or vehicle (DMSO) does not alter membrane potential/input resistance during voltage recordings[4].

CNQX (FG9065) is a potent AMPA/kainate receptor antagonist.

In rat hippocampal slices bathed in Mg2+-free medium, 10 μM CNQX reversibly blocks responses to a-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA), quisqualate and kainate but not NMDA[1]. Superfusion of hippocampal slices with 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 2-5 μM) reversibly blocks the Schaffer collateral and mossy fibre excitatory postsynaptic potential (EPSP), while sparing the fast and slow GABA-mediated inhibition[2]. CNQX (1-5 μM) produces a selective and dose-dependent reduction in the amplitude of the monosynaptic component of the DR-VRR recorded from lumbar spinal segments[3]. CNQX-mediated depolarizations are mediated by AMPAR but not kainate receptors in TRN neurons[4].

The bilateral infusion of CNQX (0.5 or 1.25 μg) into the amygdala or dorsal hippocampus 10 min prior to a retention test partially blocks the expression of stepdown inhibitory avoidance in rats 24 h after training. CNQX causes a complete blockade at a dose of 0.5 μg[5].

References:
[1]. Blake JF, et al. CNQX blocks acidic amino acid induced depolarizations and synaptic components mediated by non-NMDA receptors in rathippocampal slices. Neurosci Lett. 1988 Jun 29;89(2):182-6.
[2]. Neuman RS, et al. Blockade of excitatory synaptic transmission by 6-cyano-7-nitroquinoxaline-2,3-dione(CNQX) in the hippocampus in vitro. Neurosci Lett. 1988 Sep 23;92(1):64-8.
[3]. Alford S, et al. CNQX and DNQX block non-NMDA synaptic transmission but not NMDA-evoked locomotion in lamprey spinal cord. Brain Res. 1990 Jan 8;506(2):297-302.
[4]. Lee SH, et al. Selective excitatory actions of DNQX and CNQX in rat thalamic neurons. J Neurophysiol. 2010 Apr;103(4):1728-34.
[5]. Kim M, et al. Infusion of the non-NMDA receptor antagonist CNQX into the amygdala blocks the expression of fear-potentiated startle. Behav Neural Biol. 1993 Jan;59(1):5-8.