title: BDNF locally potentiates GABAergic presynaptic machineries: target-selective circuit inhibition.
abstract: Inhibitory neurotransmission is critical for neuronal circuit formation. To examine whether inhibitory neurotransmission receives target-selective modulation in the long term, we expressed the cDNA of brain-derived neurotrophic factor (BDNF), which has been shown to induce the augmentation of GABAergic synapses in vivo and in vitro, in a small population of cultured hippocampal neurons. At 48 h after transfection, the expression level of glutamic acid decarboxylase 65 (GAD65), a GABA synthetic enzyme that resides mainly in GABAergic terminals, was selectively enhanced around the BDNF-expressing neurons, in comparison with the neighboring control neurons interposed between the BDNF-expressing neurons and inhibitory neurons. Exogenous BDNF application for 48 h also increased the GAD level and enhanced the GABA release probability. These potentiating effects were attenuated in inhibitory synapses on neurons expressing a dominant negative form of the BDNF receptor (tTrkB). This suggests that postsynaptic BDNF-TrkB signaling contributes to the target-selective potentiation of inhibitory presynaptic machineries. Since BDNF is expressed in an activity-dependent manner in vivo, this selectivity may be one of the key mechanisms by which the independence of functional neuronal circuits is maintained.
authors.affiliation: Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Shizu
authors.initials: S
authors.lastname: Ohba
authors.forename: Takamitsu
authors.initials: T
authors.lastname: Ikeda
authors.forename: Yuji
authors.initials: Y
authors.lastname: Ikegaya
authors.forename: Nobuyoshi
authors.initials: N
authors.lastname: Nishiyama
authors.forename: Norio
authors.initials: N
authors.lastname: Matsuki
authors.forename: Maki K
authors.initials: MK
authors.lastname: Yamada
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D005968:Glutamate Decarboxylase / Q000378:metabolism; D006624:Hippocampus / Q000502:physiology*; D009433:Neural Inhibition / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology; D009474:Neurons / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D017661:Receptors, Presynaptic / Q000502:physiology; D011994:Recombinant Proteins / Q000378:metabolism; D009435:Synaptic Transmission / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D017661:Receptors, Presynaptic; D011994:Recombinant Proteins; D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase