title: GABA regulates the multidirectional tangential migration of GABAergic interneurons in living neonatal mice.
abstract: Cortical GABAergic interneurons originate from ganglionic eminences and tangentially migrate into the cortical plate at early developmental stages. To elucidate the characteristics of this migration of GABAergic interneurons in living animals, we established an experimental design specialized for in vivo time-lapse imaging of the neocortex of neonate mice with two-photon laser-scanning microscopy. In vesicular GABA/glycine transporter (VGAT)-Venus transgenic mice from birth (P0) through P3, we observed multidirectional tangential migration of genetically-defined GABAergic interneurons in the neocortical marginal zone. The properties of this migration, such as the motility rate (distance/hr), the direction moved, and the proportion of migrating neurons to stationary neurons, did not change through P0 to P3, although the density of GABAergic neurons at the marginal zone decreased with age. Thus, the characteristics of the tangential motility of individual GABAergic neurons remained constant in development. Pharmacological block of GABA(A) receptors and of the Na⁺-K⁺-Cl⁻ cotransporters, and chelating intracellular Ca²⁺, all significantly reduced the motility rate in vivo. The motility rate and GABA content within the cortex of neonatal VGAT-Venus transgenic mice were significantly greater than those of GAD67-GFP knock-in mice, suggesting that extracellular GABA concentration could facilitate the multidirectional tangential migration. Indeed, diazepam applied to GAD67-GFP mice increased the motility rate substantially. In an in vitro neocortical slice preparation, we confirmed that GABA induced a NKCC sensitive depolarization of GABAergic interneurons in VGAT-Venus mice at P0-P3. Thus, activation of GABA(A)R by ambient GABA depolarizes GABAergic interneurons, leading to an acceleration of their multidirectional motility in vivo.
authors.affiliation: Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Inada
authors.forename: Miho
authors.initials: M
authors.lastname: Watanabe
authors.forename: Taku
authors.initials: T
authors.lastname: Uchida
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Ishibashi
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Wake
authors.forename: Tomomi
authors.initials: T
authors.lastname: Nemoto
authors.forename: Yuchio
authors.initials: Y
authors.lastname: Yanagawa
authors.forename: Atsuo
authors.initials: A
authors.lastname: Fukuda
authors.forename: Junichi
authors.initials: J
authors.lastname: Nabekura
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002465:Cell Movement; D002540:Cerebral Cortex / Q000166:cytology / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D005260:Female; D059330:GABAergic Neurons / Q000166:cytology* / Q000378:metabolism*; D005786:Gene Expression Regulation; D005968:Glutamate Decarboxylase / Q000235:genetics; D006096:Gramicidin / Q000378:metabolism; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D008853:Microscopy; D057054:Molecular Imaging; D018408:Patch-Clamp Techniques; D011963:Receptors, GABA-A / Q000378:metabolism; D013997:Time Factors; D050495:Vesicular Inhibitory Amino Acid Transport Proteins / Q000235:genetics; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D002712:Chlorides; D011963:Receptors, GABA-A; D050495:Vesicular Inhibitory Amino Acid Transport Proteins; C493406:vesicular GABA transporter; D006096:Gramicidin; D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1