title: The amount of astrocytic GABA positively correlates with the degree of tonic inhibition in hippocampal CA1 and cerebellum.
abstract: A tonic form of synaptic inhibition occurs in discrete regions of the central nervous system and has an important role in controlling neuronal excitability. Recently, we reported that GABA present in astrocyte is the major source of tonic inhibition in cerebellum and that GABA is released through Bestrophin-1 channel by direct permeation. In this study, we screened for the presence of astrocytic GABA in various brain regions such as hippocampus, thalamus, hypothalamus and cerebellum using immunohistochemistry. We found that astrocytic GABA was present in the regions that were reported to show tonic inhibition. Because the existence of tonic inhibition in hippocampal CA1 is somewhat controversial, we compared the amount of astrocytic GABA and tonic inhibition between the hippocampal CA1 pyramidal cell layer and the cerebellar granule cell layer. Unlike cerebellar glial cells, hippocampal astrocytes did not contain GABA. The tonic inhibition was also much lower in the pyramidal neurons of hippocampal CA1 compared to the granule cells of cerebellum. Nevertheless, most of the hippocampal astrocytes expressed Bestrophin-1 channel. These data indicate that the absence of astrocytic GABA results in a low level of tonic inhibition in hippocampal CA1 region.
authors: WCI Center for Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul 136-791, Korea.
authors: Bo-Eun
authors: BE
authors: Yoon
authors: Seonmi
authors: S
authors: Jo
authors: Junsung
authors: J
authors: Woo
authors: Jae-Hoon
authors: JH
authors: Lee
authors: Taekeun
authors: T
authors: Kim
authors: Daesoo
authors: D
authors: Kim
authors: C Justin
authors: CJ
authors: Lee
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000502:physiology*; D000075002:Bestrophins; D001640:Bicuculline / Q000378:metabolism; D056547:CA1 Region, Hippocampal / Q000166:cytology / Q000502:physiology*; D002531:Cerebellum / Q000166:cytology / Q000502:physiology*; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism; D058787:GABA-A Receptor Antagonists / Q000378:metabolism; D005904:Glial Fibrillary Acidic Protein / Q000235:genetics / Q000378:metabolism; D007473:Ion Channels / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009433:Neural Inhibition / Q000502:physiology*; D011724:Pyridazines / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: C491856:Best1 protein, mouse; D000075002:Bestrophins; D005136:Eye Proteins; D058787:GABA-A Receptor Antagonists; D005904:Glial Fibrillary Acidic Protein; D007473:Ion Channels; D011724:Pyridazines; D011993:Recombinant Fusion Proteins; D005680:gamma-Aminobutyric Acid; C049853:gabazine; D001640:Bicuculline