title: Redistribution of microtubules in dendrites of hippocampal CA1 neurons after tetanic stimulation during long-term potentiation.
abstract: It is now well accepted that the trafficking of AMPA receptors to the postsynaptic plasma membrane plays an essential role in long-term potentiation at the hippocampal Schaffer collateral synapses on CA1 pyramidal cells, but the motor mechanism of trafficking is unknown. We suspected that this trafficking of AMPA receptors during long-term potentiation may be carried out along microtubules by their motors. To ascertain this hypothesis, we light- and electron-microscopically studied the distribution of microtubules in dendrites of CA1 neurons of non-stimulated and stimulated rat hippocampal slices by using very strong tetanic stimulation for inducing long-term potentiation. As a result, we observed the following changes: 1. In immunofluorescence for microtubules and IP3 receptor using ultrathin-cryosections, linear signals of microtubules in main dendritic shafts were changed into fragmented. 2. Many spotty signals of microtubules emerged at the peripheral area of dendrites. Electron-microscopically, there was redistribution of microtubules in dendritic spines and dendritic shafts, and the thickening of post-synaptic density. 3. Many microtubules concentrated to thickened postsynaptic density in spines and new ones emerged, going to spines from dendritic shafts. These results strongly suggest that new tracks of microtubules from cell bodies to the stimulated postsynaptic membranes were produced after tetanic stimulation during long-term potentiation. This newly produced microtubules between stimulated postsynaptic membranes and the cell body must be the most promising candidate of the track for the trafficking of AMPA receptors to the stimulated postsynaptic plasma membrane.
authors.affiliation: Department of Neurosurgery, Fujita Health University, Aichi, Japan. fmituyam@hotmail.com
authors.forename: Fuyuki
authors.initials: F
authors.lastname: Mitsuyama
authors.forename: Gen
authors.initials: G
authors.lastname: Niimi
authors.forename: Kunio
authors.initials: K
authors.lastname: Kato
authors.forename: Kazushige
authors.initials: K
authors.lastname: Hirosawa
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Mikoshiba
authors.forename: Masato
authors.initials: M
authors.lastname: Okuya
authors.forename: Kostadin
authors.initials: K
authors.lastname: Karagiozov
authors.forename: Yoko
authors.initials: Y
authors.lastname: Kato
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Kanno
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Sanoe
authors.forename: Tadashi
authors.initials: T
authors.lastname: Koide
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D003712:Dendrites / Q000378:metabolism / Q000648:ultrastructure*; D049229:Dendritic Spines / Q000502:physiology / Q000648:ultrastructure; D004558:Electric Stimulation; D005455:Fluorescent Antibody Technique; D006624:Hippocampus / Q000378:metabolism / Q000648:ultrastructure*; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000378:metabolism; D017774:Long-Term Potentiation / Q000502:physiology*; D046529:Microscopy, Electron, Transmission; D008870:Microtubules / Q000378:metabolism / Q000648:ultrastructure*; D020409:Molecular Motor Proteins / Q000378:metabolism; D009924:Organ Culture Techniques; D021381:Protein Transport / Q000502:physiology; D017966:Pyramidal Cells / Q000378:metabolism / Q000648:ultrastructure*; D051381:Rats; D018091:Receptors, AMPA / Q000378:metabolism; D013569:Synapses / Q000378:metabolism / Q000648:ultrastructure; D013570:Synaptic Membranes / Q000502:physiology / Q000648:ultrastructure; D009435:Synaptic Transmission / Q000502:physiology
chemical_list: D053496:Inositol 1,4,5-Trisphosphate Receptors; D020409:Molecular Motor Proteins; D018091:Receptors, AMPA