title: Differential roles of NR2A and NR2B-containing NMDA receptors in LTP and LTD in the CA1 region of two-week old rat hippocampus.
abstract: The role of NMDA receptors in the induction of long-term potentiation (LTP) and long-term depression (LTD) is well established but which particular NR2 subunits are involved in these plasticity processes is still a matter of controversy. We have studied the effects of subtype selective NMDA receptor antagonists on LTP induced by high frequency stimulation (100 Hz for 1s) and LTD induced by low frequency stimulation (1 Hz for 15 min) in the CA1 region of hippocampal slices from 14 day old Wistar rats. Against recombinant receptors in HEK293 cells NVP-AAM077 (NVP) was approximately 14-fold selective for NR2A vs NR2B receptors, whilst Ro 25-6981 (Ro) was highly selective for NR2B receptors. On NMDA receptor-mediated EPSCs from Schaffer collaterals in CA1 neurones, NVP and Ro both reduced the amplitude but differentially affected the time constant of decay. The data are compatible with the selective effect of NVP (0.1 microM) and Ro (4 microM) on native NR2A and NBR2B receptors, respectively. NVP reduced both LTP and LTD whereas Ro reduced only LTP. Thus, LTP was reduced by 63% at 0.1 microM NVP and almost completely at 0.4 microM whereas 5 microM Ro reduced LTP by 45%. These data are consistent with a role for both NR2A and NR2B in the induction of LTP, under our experimental conditions. In comparison, LTD was unaffected by Ro (5 microM) even in the presence of a glutamate uptake inhibitor threo-beta-benzylaspartic acid (TBOA) to increase the concentration of glutamate at NR2B containing receptors. NVP (0.2-0.4 microM), however, produced a concentration dependent inhibition of LTD which was complete at 0.4 microM. The lack of effect of 0.1 microM NVP on LTD contrasts with its marked effect on LTP and raises the possibility that different NVP-sensitive NR2 subunit-containing NMDA receptors are required for LTP and LTD in this preparation.
authors.affiliation: MRC Centre for Synaptic Plasticity, Department of Anatomy, University of Bristol, School of Medical Sciences, University Walk, Bristol, BS8 1TD, UK.
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Bartlett
authors.forename: Neil J
authors.initials: NJ
authors.lastname: Bannister
authors.forename: Valerie J
authors.initials: VJ
authors.lastname: Collett
authors.forename: Sheila L
authors.initials: SL
authors.lastname: Dargan
authors.forename: Peter V
authors.initials: PV
authors.lastname: Massey
authors.forename: Zuner A
authors.initials: ZA
authors.lastname: Bortolotto
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Fitzjohn
authors.forename: Zafar I
authors.initials: ZI
authors.lastname: Bashir
authors.forename: Graham L
authors.initials: GL
authors.lastname: Collingridge
authors.forename: David
authors.initials: D
authors.lastname: Lodge
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002461:Cell Line, Transformed; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D004347:Drug Interactions; D004558:Electric Stimulation / Q000379:methods; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005260:Female; D006624:Hippocampus / Q000502:physiology*; D006801:Humans; D066298:In Vitro Techniques; D017774:Long-Term Potentiation / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D036881:Long-Term Synaptic Depression / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D016202:N-Methylaspartate / Q000494:pharmacology; D018408:Patch-Clamp Techniques / Q000379:methods; D010636:Phenols / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology*; D014162:Transfection / Q000379:methods
chemical_list: C498554:5-(alpha-methyl-4-bromobenzylamino)phosphonomethyl-1,4-dihydroquinoxaline-2,3-dione; D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; C120997:NR2A NMDA receptor; C121001:NR2B NMDA receptor; D010636:Phenols; D010880:Piperidines; D011810:Quinoxalines; D016194:Receptors, N-Methyl-D-Aspartate; C109643:Ro 25-6981; D016202:N-Methylaspartate