title: TrkB as a potential synaptic and behavioral tag.
abstract: Late-phase long-term potentiation (L-LTP), a cellular model for long-term memory (LTM), requires de novo protein synthesis. An attractive hypothesis for synapse specificity of long-term memory is "synaptic tagging": synaptic activity generates a tag, which "captures" the PRPs (plasticity-related proteins) derived outside of synapses. Here we provide evidence that TrkB, the receptor of BDNF (brain-derived neurotrophic factor), may serve as a "synaptic tag." TrkB is transiently activated by weak theta-burst stimulation (TBS) that induces only early-phase LTP (E-LTP). This TrkB activation is independent of protein synthesis, and confined to stimulated synapses. Induction of L-LTP by strong stimulation in one synaptic pathway converts weak TBS-induced E-LTP to L-LTP in a second, independent pathway. Transient inhibition of TrkB around the time of weak TBS to the second pathway diminished L-LTP in that pathway without affecting the first one. Behaviorally, weak training, which induces short-term memory (STM) but not LTM, can be consolidated into LTM by exposing animals to novel but not familiar environment 1 h before training. Inhibition of TrkB during STM training blocked such consolidation. These results suggest TrkB as a potential tag for synapse-specific expression of L-LTP and LTM.
authors.affiliation: Gene, Cognition and Psychosis Program, NIMH, National Institutes of Health, Bethesda, Maryland 20892-3714, USA.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Lu
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Ji
authors.forename: Sundar
authors.initials: S
authors.lastname: Ganesan
authors.forename: Robert
authors.initials: R
authors.lastname: Schloesser
authors.forename: Keri
authors.initials: K
authors.lastname: Martinowich
authors.forename: Mu
authors.initials: M
authors.lastname: Sun
authors.forename: Fan
authors.initials: F
authors.lastname: Mei
authors.forename: Moses V
authors.initials: MV
authors.lastname: Chao
authors.forename: Bai
authors.initials: B
authors.lastname: Lu
mesh_terms: D000818:Animals; D001362:Avoidance Learning / Q000502:physiology; D002478:Cells, Cultured; D055879:Gene Knock-In Techniques; D006624:Hippocampus / Q000502:physiology; D006801:Humans; D017774:Long-Term Potentiation / Q000502:physiology*; D008297:Male; D057567:Memory, Long-Term / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D011897:Random Allocation; D020813:Receptor, trkB / Q000235:genetics* / Q000378:metabolism*; D013569:Synapses / Q000235:genetics* / Q000378:metabolism*
chemical_list: D020813:Receptor, trkB