6 cyano 7 nitroquinoxaline 2 3 dione cnqx

To study ligand-gated channels AMPA and NMDA, we adopted the voltage-ramp method [85 ].
Individual currents were recorded after incubation with T₃ 1 μM (n = 4) or Vh (n = 3) during the 48 h preceding the experiments. A sequence of voltage ramps at a rate of 0.23 mV/millisecond were applied at a holding potential of − 80 mV. To obtain the agonist induced current-voltage (I-V) relation, ramps I-V curves were constructed applying a 500 milliseconds voltage ramp ranging from − 110 mV to + 20 mV elicited every 8 s. Voltage ramps were applied in the absence and in the presence of AMPA and NMDA agonist glutamate at 50 μM and co-agonist of NMDA channels glycine at 3 μM, to enable subtraction of leak currents. The antagonists of AMPA and NMDA channels, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX; Sigma-Aldrich) and dizocilpinehydrogen maleate (MK-801; Sigma-Aldrich), respectively, were used both at 10 μM.
Cell currents were recorded sequentially in the presence of specific K⁺- channel blockers tetraethylammonium sodium salt (5 mM) and 4-Aminopyridine (1 mM), that were applied in the perfusion system together with the other drugs. Voltage-gated K⁺ channels needed to be blocked, since those channels were contributing to the conductance as well to the reversal potential obtained.

Drugs were prepared as concentrated stock solutions and diluted in ACSF for bath application immediately prior to use. Gabazine, a selective GABA_A receptor antagonist; (±)-2-amino-5-phosphonopentanoic acid (AP5, a selective NMDA receptor antagonist), 6-cyano-7nitroquinoxaline 2, 3-dione (CNQX, an AMPA-KA receptors antagonist), DL-Serine 2-(2,3,4-trihydroxybenzyl)hydrazide hydrochloride (benserazide), an inhibitor of peripheral dopa decarboxylase and α-methyl-L-tyrosine (levodopa) were all purchased from Sigma Aldrich (France).