title: Suppressive effect of preconditioning low-frequency stimulation on subsequent induction of long-term potentiation by high frequency stimulation in hippocampal CA3 neurons.
abstract: We investigated the role of inositol 1, 4, 5-trisphosphate receptors (IP3Rs), activated during preconditioning low-frequency afferent stimulation (LFS), in the subsequent induction of long-term potentiation (LTP) in CA3 neurons in hippocampal slices from mature guinea pigs. Induction of LTP in the field excitatory postsynaptic potential (EPSP) by the delivery of high-frequency stimulation (HFS, a tetanus of two trains of 100 pulses at 100Hz with a 10s interval) to mossy fiber-CA3 neuron synapses was suppressed when CA3 synapses were preconditioned by the LFS of 1000 pulses at 2Hz and this effect was inhibited when the LFS preconditioning was performed in the presence of an IP3R antagonist or a protein phosphatase inhibitor. Furthermore, activation of group 1 metabotropic glutamate receptors (mGluRs) during HFS canceled the effects of an IP3R antagonist given during preconditioning LFS on the subsequent LTP induction at mossy fiber-CA3 synapses. These results suggest that, in hippocampal mossy fiber-CA3 neuron synapses, activation of IP3Rs during a preconditioning LFS results in dephosphorylation events that lead to failure of the HFS to induce subsequent LTP.
authors.affiliation: Department of Physiology, Yamagata University School of Medicine, Yamagata 990-9585, Japan.
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Yamazaki
authors.forename: Satoshi
authors.initials: S
authors.lastname: Fujii
authors.forename: Jun-Ichi
authors.initials: J
authors.lastname: Goto
authors.forename: Toshimichi
authors.initials: T
authors.lastname: Sugihara
authors.forename: Makoto
authors.initials: M
authors.lastname: Sugita
authors.forename: Hiroki
authors.initials: H
authors.lastname: Fujiwara
authors.forename: Kenya
authors.initials: K
authors.lastname: Kaneko
authors.forename: Takeshi
authors.initials: T
authors.lastname: Aihara
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Mikoshiba
mesh_terms: D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000818:Animals; D001565:Benzoates / Q000494:pharmacology; D056654:CA3 Region, Hippocampal / Q000187:drug effects / Q000502:physiology*; D004558:Electric Stimulation; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D005998:Glycine / Q000031:analogs & derivatives / Q000494:pharmacology; D006168:Guinea Pigs; D017774:Long-Term Potentiation / Q000187:drug effects / Q000502:physiology*; D019599:Mossy Fibers, Hippocampal / Q000187:drug effects / Q000502:physiology*; D010766:Phosphorylation / Q000187:drug effects / Q000502:physiology; D013569:Synapses / Q000187:drug effects / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology
chemical_list: D001565:Benzoates; D018691:Excitatory Amino Acid Antagonists; C474696:methyl-(4-carboxyphenyl)glycine; C079693:4-carboxyphenylglycine; D015763:2-Amino-5-phosphonovalerate; D005998:Glycine