Stimulation of noradrenaline release in human cerebral cortex mediated by N-methyl-D-aspartate (NMDA) and non-NMDA receptors.
1. Human brain cortical slices from patients undergoing neurosurgery for treatment of epilepsy resistant to antiepileptic drugs were used to identify and characterize N-methyl-D-aspartate (NMDA) and non-NMDA receptors mediating stimulation of noradrenaline release. The slices preincubated with [3H]-noradrenaline were superfused with Krebs-Henseleit solution with or without Mg2+ (1.2 mmol l-1) and were stimulated by 2-min exposure to NMDA, kainic acid or (RS)-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA). 2. In slices superfused without Mg2+, NMDA induced a concentration-dependent tritium overflow. 3. The NMDA-evoked tritium overflow was almost abolished by tetrodotoxin (TTX), Mg2+ or by omission of Ca2+ from the superfusion fluid. 2-Amino-5-phosphonopentanoic acid (AP5; a competitive NMDA receptor antagonist) or dizocilpine (formerly MK-801; an antagonist at the phencyclidine receptor within the NMDA-gated ion channel) inhibited the NMDA-evoked tritium overflow. The stimulatory effect of NMDA was not significantly enhanced by glycine added to the superfusion fluid but was reduced by 7-chlorokynurenic acid (an antagonist at the glycine site coupled to the NMDA receptor). 4. In slices superfused with solution containing Mg2+, kainic acid or AMPA induced a concentration-dependent tritium overflow which was susceptible to blockade by TTX. 5. The kainic acid-evoked tritium overflow was not affected by DL-(E)-2-amino-4-methyl-5-phosphono-3-pentanoic acid (CGP37849; a competitive NMDA receptor antagonist), but was inhibited by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX; an antagonist at glutamate receptors of the non-NMDA type). 6. The AMPA-evoked tritium overflow was also inhibited by CNQX.2ń
Fink
K
K
Institute of Pharmacology and Toxicology, University of Bonn, Germany.
Schultheiss
R
R
Göthert
M
M
D015763:2-Amino-5-phosphonovalerate / Q000031:analogs & derivatives / Q000494:pharmacology; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D000328:Adult; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism*; D016291:Dizocilpine Maleate / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D005998:Glycine / Q000494:pharmacology; D006801:Humans; D007051:Ibotenic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D007608:Kainic Acid / Q000494:pharmacology*; D007736:Kynurenic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D016202:N-Methylaspartate / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D009638:Norepinephrine / Q000378:metabolism*; D011810:Quinoxalines / Q000494:pharmacology; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology; D014316:Tritium / Q000378:metabolism; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid
D011810:Quinoxalines; D016194:Receptors, N-Methyl-D-Aspartate; D014316:Tritium; C064539:2-amino-4-methyl-5-phosphono-3-pentenoic acid; D007051:Ibotenic Acid; D013779:Tetrodotoxin; D016202:N-Methylaspartate; D016291:Dizocilpine Maleate; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D015763:2-Amino-5-phosphonovalerate; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; D007736:Kynurenic Acid; D008274:Magnesium; C057013:7-chlorokynurenic acid; D007608:Kainic Acid; D005998:Glycine; D009638:Norepinephrine