title: Paired stimulation between CA3 and CA1 alters excitability of CA3 in the rat hippocampus.
abstract: It is generally accepted that the extent of plasticity is localized to the region around synapses and post-synaptic intracellular signaling cascades. We investigated the presence of long-range retrograde plasticity associated with excitability at pre-synaptic neurons (CA3) and regulated by the firing of post-synaptic neurons (CA1). We used acute hippocampus slices from transgenic rats expressing channelrhodopsin-2 (ChR2) in both CA1 and CA3 neurons. We employed a parallel photostimulation technique, which enabled robust and independent evocation of action potentials in either CA3 or CA1 neurons. Optically evoked CA3 firings were paired either with CA1 simultaneous firings or with CA1 suppression after the prolonged stimulation. Pre-synaptic excitability was monitored by measuring the optically-evoked firing rate (Opt-FR). We found that the Opt-FR of CA3 neurons was long-term up-regulated as a result of synchronous pre- and post-synaptic pairing stimulation, but down-regulated by the pre-synaptic stimulation during post-synaptic suppression. Both pairing-dependent up-regulation and down-regulation were retarded by NMDA receptor blocking or colchicine preincubation. This finding suggest that CA3 excitability is regulated by CA1 neuron activity at the time of CA3 firing.
authors.affiliation: Department of Physiology, National Defense Medical College, Tokorozawa, Japan. ohta@ndmc.ac.jp
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ohta
authors.forename: Seiichiro
authors.initials: S
authors.lastname: Sakai
authors.forename: Shin
authors.initials: S
authors.lastname: Ito
authors.forename: Toru
authors.initials: T
authors.lastname: Ishizuka
authors.forename: Yugo
authors.initials: Y
authors.lastname: Fukazawa
authors.forename: Takehito
authors.initials: T
authors.lastname: Kemuriyama
authors.forename: Megumi
authors.initials: M
authors.lastname: Tandai-Hiruma
authors.forename: Hajime
authors.initials: H
authors.lastname: Mushiake
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Sato
authors.forename: Hiromu
authors.initials: H
authors.lastname: Yawo
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Nishida
mesh_terms: D000200:Action Potentials; D000818:Animals; D056547:CA1 Region, Hippocampal / Q000187:drug effects / Q000502:physiology*; D056654:CA3 Region, Hippocampal / Q000187:drug effects / Q000502:physiology*; D000075402:Channelrhodopsins; D003078:Colchicine / Q000494:pharmacology; D066298:In Vitro Techniques; D009474:Neurons / Q000502:physiology; D010775:Photic Stimulation; D051381:Rats; D055647:Rats, Transgenic; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors; D013569:Synapses / Q000502:physiology; D014633:Valine / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D000075402:Channelrhodopsins; D016194:Receptors, N-Methyl-D-Aspartate; C056639:2-amino-5-phosphopentanoic acid; D014633:Valine; D003078:Colchicine