title: Brain-derived neurotrophic factor controls functional differentiation and microcircuit formation of selectively isolated fast-spiking GABAergic interneurons.
abstract: GABAergic interneurons with high-frequency firing, fast-spiking (FS) cells, form synapses on perisomatic regions of principal cells in the neocortex and hippocampus to control the excitability of cortical networks. Brain-derived neurotrophic factor (BDNF) is essential for the differentiation of multiple interneuron subtypes and the formation of their synaptic contacts. Here, we examined whether BDNF, alone or in conjunction with sustained KCl-induced depolarization, drives functional FS cell differentiation and the formation of inhibitory microcircuits. Homogeneous FS cell cultures were established by target-specific isolation using the voltage-gated potassium channel 3.1b subunit as the selection marker. Isolated FS cells expressed parvalbumin, were surrounded by perineuronal nets, formed immature inhibitory connections and generated slow action potentials at 12 days in vitro. Brain-derived neurotrophic factor (BDNF) promoted FS cell differentiation by increasing the somatic diameter, dendritic branching and the frequency of action potential firing. In addition, BDNF treatment led to a significant up-regulation of synaptophysin and vesicular GABA transporter expression, components of the synaptic machinery critical for GABA release, which was paralleled by an increase in synaptic strength. Long-term membrane depolarization alone was detrimental to dendritic branching. However, we observed that BDNF and KCl exerted additive effects, as reflected by the significantly accelerated maturation of synaptic contacts and high discharge frequencies, and was required for the formation of reciprocal connections between FS cells. Our results show that BDNF, along with membrane depolarization, is critical for FS cells to establish inhibitory circuitries during corticogenesis.
authors.affiliation: Laboratory of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Scheeles väg 1:A1, Karolinska Institutet, S-17177 Stockholm, Sweden.
authors.forename: Paul
authors.initials: P
authors.lastname: Berghuis
authors.forename: Marton B
authors.initials: MB
authors.lastname: Dobszay
authors.forename: Kyle M
authors.initials: KM
authors.lastname: Sousa
authors.forename: Gunnar
authors.initials: G
authors.lastname: Schulte
authors.forename: Peter P
authors.initials: PP
authors.lastname: Mager
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Härtig
authors.forename: Tamás J
authors.initials: TJ
authors.lastname: Görcs
authors.forename: Yuri
authors.initials: Y
authors.lastname: Zilberter
authors.forename: Patrik
authors.initials: P
authors.lastname: Ernfors
authors.forename: Tibor
authors.initials: T
authors.lastname: Harkany
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000502:physiology*; D002454:Cell Differentiation / Q000502:physiology*; D002478:Cells, Cultured; D005260:Female; D007395:Interneurons / Q000166:cytology / Q000502:physiology; D009415:Nerve Net / Q000166:cytology / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000502:physiology; D015221:Potassium Channels / Q000502:physiology; D024642:Potassium Channels, Voltage-Gated; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D051670:Shaw Potassium Channels; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
chemical_list: D019208:Brain-Derived Neurotrophic Factor; C098254:Kcnc1 protein, rat; D009419:Nerve Tissue Proteins; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D051670:Shaw Potassium Channels; D005680:gamma-Aminobutyric Acid