title: GABA(A) Increases Calcium in Subventricular Zone Astrocyte-Like Cells Through L- and T-Type Voltage-Gated Calcium Channels.
abstract: In the adult neurogenic subventricular zone (SVZ), the behavior of astrocyte-like cells and some of their functions depend on changes in intracellular Ca(2+) levels and tonic GABA(A) receptor activation. However, it is unknown whether, and if so how, GABA(A) receptor activity regulates intracellular Ca(2+) dynamics in SVZ astrocytes. To monitor Ca(2+) activity selectively in astrocyte-like cells, we used two lines of transgenic mice expressing either GFP fused to a Gq-coupled receptor or DsRed under the human glial fibrillary acidic protein (hGFAP) promoter. GABA(A) receptor activation induced Ca(2+) increases in 40-50% of SVZ astrocytes. GABA(A)-induced Ca(2+) increases were prevented with nifedipine and mibefradil, blockers of L- and T-type voltage-gated calcium channels (VGCC). The L-type Ca(2+) channel activator BayK 8644 increased the percentage of GABA(A)-responding astrocyte-like cells to 75%, suggesting that the majority of SVZ astrocytes express functional VGCCs. SVZ astrocytes also displayed spontaneous Ca(2+) activity, the frequency of which was regulated by tonic GABA(A) receptor activation. These data support a role for ambient GABA in tonically regulating intracellular Ca(2+) dynamics through GABA(A) receptors and VGCC in a subpopulation of astrocyte-like cells in the postnatal SVZ.
authors.affiliation: Departments of Neurosurgery and Cellular & Molecular Physiology, Yale University School of Medicine New Haven, CT, USA.
authors.forename: Stephanie Z
authors.initials: SZ
authors.lastname: Young
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Platel
authors.forename: Jakob V
authors.initials: JV
authors.lastname: Nielsen
authors.forename: Niels A
authors.initials: NA
authors.lastname: Jensen
authors.forename: Angélique
authors.initials: A
authors.lastname: Bordey