Article date: 1991/1/2
PubMed ID: 1673549
Journal name: Neuroscience letters (ISSN: 0304-3940)
The action of the non-N-methyl-D-aspartate (non-NMDA) receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) on gamma-aminobutyric acid-A (GABAA) receptor-mediated currents was studied in dissociated rat midbrain and hypothalamic cultures using whole-cell recording. Spontaneous synaptic activity consisted of excitatory (EPSCs) and inhibitory postsynaptic currents (IPSCs). Bicuculline (20 microM) blocked IPSCs and increased the frequency of EPSCs. CNQX (1 microM) reduced both EPSCs and IPSCs. In the presence of 0.3 microM tetrodotoxin (TTX), CNQX (1-20 microM) blocked miniature EPSCs and reduced IPSCs. In TTX, increasing K+ (20 mM) evoked EPSCs and IPSCs in a Ca-dependent manner. CNQX (10 microM) blocked evoked EPSCs and diminished evoked IPSCs similarly as miniature IPSCs. Muscimol-(0.2-5 microM) induced currents were dose-dependently reduced by CNQX (10-50 microM). It is concluded that CNQX reduces GABAA receptor-mediated inhibition primarily by reducing the excitatory drive in the evolving network, but, in addition, has a significant blocking effect on the GABAA receptor-channel complex.
Author List: Jarolimek W, Misgeld U
Publication Types: Comparative Study; Journal Article; Research Support, Non-U.S. Gov't
Substances mentioned in the article: GABA-A Receptor Antagonists; Quinoxalines; Receptors, GABA-A; Receptors, N-Methyl-D-Aspartate; Cadmium; Muscimol; Tetrodotoxin; 6-Cyano-7-nitroquinoxaline-2,3-dione; Potassium; Bicuculline;
Mesh terms: 6-Cyano-7-nitroquinoxaline-2,3-dione; Animals; Bicuculline/pharmacology; Brain/cytology; Cadmium/pharmacology; Cells, Cultured; Embryo, Mammalian/cytology; Female; GABA-A Receptor Antagonists; Muscimol/pharmacology; Neuroglia/cytology; Neurons/drug effects; Potassium/pharmacology; Pregnancy; Quinoxalines/pharmacology; Rats; Receptors, GABA-A/physiology; Receptors, N-Methyl-D-Aspartate/physiology; Tetrodotoxin/pharmacology;