Cooperativity between activation of metabotropic glutamate receptors and NMDA receptors in the induction of LTP in hippocampal CA1 neurons.
In CA1 neurons of guinea pig hippocampal slices, long-term potentiation (LTP) was induced by 10 min application of 10 microM aminocyclopentane-1S, 3R-dicarboxylic acid (ACPD), the metabotropic glutamate receptor (mGluR) agonist, in the presence of test synaptic inputs (once every 20 s). In contrast, long-term depression (LTD) was induced by application of 10 microM ACPD in the absence of test inputs. When 10 microM ACPD was applied in the presence of test inputs, co-application of the N-methyl-D-aspartate (NMDA) receptor antagonist, D,L-2-amino-5-phosphonovalerate resulted in LTD induction when used at 50 microM. In ACPD-induced LTP, the delivery of test synaptic inputs to CA1 neurons could be replaced by co-application of NMDA (100 nM) during ACPD perfusion. These results suggest that, in CA1 neurons, a co-operative effect involving the activation of both mGluRs and NMDA receptors is required to trigger the process involved in ACPD-induced LTP. In addition, ACPD-induced LTD was blocked by co-application of an inositol 1,4,5-trisphosphate (IP3) receptor inhibitor, 2-aminotheoxydiphenyl borate (10 microM), which had no effect on ACPD-induced LTP. The results of the present study, therefore, indicate that ACPD-induced LTP involves NMDA receptors, but not IP3 receptors, whereas the converse applies to ACPD-induced LTD.
Fujii
Satoshi
S
Department of Physiology, Yamagata University School of Medicine, Yamagata 990-9585, Japan. sfujii@med.id.yamagata-u.ac.jp
Mikoshiba
Katsuhiko
K
Kuroda
Yoichiro
Y
Ahmed
Taufiq M
TM
Kato
Hiroshi
H
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000818:Animals; D001896:Boron Compounds / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D003515:Cycloleucine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004558:Electric Stimulation; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D005998:Glycine / Q000031:analogs & derivatives / Q000494:pharmacology; D006168:Guinea Pigs; D006624:Hippocampus / Q000166:cytology* / Q000187:drug effects; D066298:In Vitro Techniques; D017774:Long-Term Potentiation / Q000187:drug effects / Q000502:physiology*; D036881:Long-Term Synaptic Depression / Q000187:drug effects / Q000502:physiology; D008297:Male; D016202:N-Methylaspartate / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D018094:Receptors, Metabotropic Glutamate / Q000819:agonists / Q000037:antagonists & inhibitors / Q000502:physiology*; D016194:Receptors, N-Methyl-D-Aspartate / Q000819:agonists / Q000037:antagonists & inhibitors / Q000502:physiology*; D013997:Time Factors
D001896:Boron Compounds; D018094:Receptors, Metabotropic Glutamate; D016194:Receptors, N-Methyl-D-Aspartate; C474696:methyl-(4-carboxyphenyl)glycine; D003515:Cycloleucine; D016202:N-Methylaspartate; D015763:2-Amino-5-phosphonovalerate; C109986:2-aminoethoxydiphenyl borate; D002118:Calcium; D005998:Glycine