Pharmacology of 5-chloro-7-trifluoromethyl-1,4-dihydro-2,3-quinoxalinedione: a novel systemically active ionotropic glutamate receptor antagonist.
5-Chloro-7-trifluoromethyl-1,4-dihydro-2,3-quinoxalinedione (ACEA-1011) has analgesic properties in animal models of tonic pain. To investigate the mechanisms underlying this effect we used electrical recording techniques to characterize the in vitro pharmacology of ACEA-1011 at mammalian glutamate receptors. Two preparations were used: Xenopus oocytes expressing rat brain receptors and cultured rat cortical neurons. Results showed that ACEA-1011 is a competitive antagonist at NMDA receptor glycine sites. Apparent antagonist affinities (Kb values) were 0.4 to 0.8 microM in oocytes and approximately 0.6 microM in neurons. IC50 values for ACEA-1011 against four binary subunit combinations of cloned rat NMDA receptors (NR1A/NR2A, 2B, 2C or 2D) ranged from 0.4 to 8 microM (1 microM glycine). The 20-fold variation in sensitivity was due to a combination of subunit-dependent differences in glycine and antagonist affinities; EC50 values for glycine ranged between 0.08 to 0.8 microM and Kb values for ACEA-1011 between 0.2 to 0.8 microM. In addition, ACEA-1011 inhibited AMPA-preferring non-NMDA receptors by competitive antagonism at glutamate binding sites. Kb values were 4 to 9 microM in oocytes and 9 to 10 microM in neurons. The ED50 for ACEA-1011 in a mouse maximum electroshock-induced seizure model was approximately 12 mg/kg i.v.. Our results indicate that ACEA-1011 is a systemically active broad selectivity ionotropic glutamate receptor antagonist.
Acea Pharmaceuticals Inc., Irvine, California, USA.
R M
RM
Woodward
J E
JE
Huettner
M
M
Tran
J
J
Guastella
J F
JF
Keana
E
E
Weber
D000700:Analgesics / Q000494:pharmacology*; D000818:Animals; D000927:Anticonvulsants / Q000494:pharmacology; D001921:Brain / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D002478:Cells, Cultured; D003001:Cloning, Molecular; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology*; D051379:Mice; D009474:Neurons / Q000502:physiology; D011810:Quinoxalines / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017470:Receptors, Glutamate / Q000378:metabolism*; D012640:Seizures / Q000503:physiopathology / Q000517:prevention & control; D014982:Xenopus laevis
D000700:Analgesics; D000927:Anticonvulsants; D018691:Excitatory Amino Acid Antagonists; D011810:Quinoxalines; D012333:RNA, Messenger; D017470:Receptors, Glutamate; C082999:ACEA 1011