Epileptiform bursts elicited in CA3 hippocampal neurons by a variety of convulsants are not blocked by N-methyl-D-aspartate antagonists.
Intracellular and extracellular recordings from CA3 hippocampal neurons in vitro were used to study the ability of several NMDA (N-methyl-D-aspartate) receptor antagonists to suppress epileptiform bursts induced by NMDA and convulsants not thought to act at NMDA receptors. The antagonists, APV (D-2-amino-5-phosphonovalerate), AP-7 (D,L-2-amino-7-phosphonohepatanoate) and CPP (D,L-3[(+/-)-2-carboxypiperazin-4-yl]-propyl-1-phosphonic acid), blocked the spontaneous and evoked bursts induced by NMDA. CPP, but not APV or AP-7, prevented the development of bursts induced by Mg-free medium. The NMDA antagonists failed to block bursting induced by kainate, 7 mM K+, mast cell degranulating peptide, anoxia or spontaneous bursting. In some cases the NMDA antagonists induced spontaneous bursts or enhanced burst frequency, a proconvulsant effect. It is concluded that activation of NMDA receptors is sufficient but not necessary for burst generation in the CA3 region.
D015763:2-Amino-5-phosphonovalerate / Q000031:analogs & derivatives; D000200:Action Potentials / Q000187:drug effects; D000596:Amino Acids / Q000494:pharmacology; D000818:Animals; D000927:Anticonvulsants / Q000494:pharmacology*; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D003292:Convulsants / Q000494:pharmacology*; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D007608:Kainic Acid / Q000494:pharmacology; D007696:Kindling, Neurologic / Q000187:drug effects*; D016202:N-Methylaspartate; D010879:Piperazines / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter / Q000187:drug effects / Q000502:physiology*; D014633:Valine / Q000031:analogs & derivatives / Q000494:pharmacology
D000596:Amino Acids; D000927:Anticonvulsants; D003292:Convulsants; D010879:Piperazines; D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter; D001224:Aspartic Acid; D016202:N-Methylaspartate; D015763:2-Amino-5-phosphonovalerate; C050592:3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid; D014633:Valine; C031231:2-amino-7-phosphonoheptanoic acid; D007608:Kainic Acid