GABA is proposed to act as a gliotransmitter in the brain. Differences in GABA release from astroglia are thought to underlie differences in tonic inhibition between the cerebellum and the CA1 hippocampus. Here we used quantitative immunogold cytochemistry to localize and compare the levels of GABA in astroglia in these brain regions. We found that the density of GABA immunogold particles was similar in delicate processes of Bergman glia in the cerebellum and astrocytes in the CA1 hippocampus. The astrocytic GABA release is proposed to be mediated by, among others, the Ca²⁺ activated Cl^– channel bestrophin-1. The bestrophin-1 antibodies did not show any significant bestrophin-1 signal in the brain of wt mice, nor in bestrophin-1 knockout mice. The bestrophin-1 signal was low both on Western blots and immunofluorescence laser scanning microscopic images. These results suggest that GABA is localized in astroglia, but in similar concentrations in the cerebellum and CA1 hippocampus, and thus cannot account for differences in tonic inhibition between these brain regions. Furthermore, our data seem to suggest that the GABA release from astroglia previously observed in the hippocampus and cerebellum occurs via mechanisms other than bestrophin-1.

GABA被提议充当大脑中的神经胶质递质。星形胶质细胞释放GABA的差异被认为是小脑与CA1海马之间进补抑制作用的差异的基础。在这里，我们使用定量免疫金细胞化学技术来定位和比较这些大脑区域的星形胶质细胞中GABA的水平。我们发现，小脑Bergman胶质细胞和CA1海马的星形胶质细胞的精细过程中，GABA免疫金颗粒的密度相似。星形细胞GABA的释放被认为是由Ca ²⁺活化的Cl ^–通道Bestrophin-1。Bestrophin-1抗体在wt小鼠的大脑中和Bestrophin-1基因敲除小鼠的脑中均未显示任何明显的Bestrophin-1信号。在蛋白质印迹和免疫荧光激光扫描显微图像上，Bestrophin-1信号均较低。这些结果表明，GABA位于星形胶质细胞中，但在小脑和CA1海马中的浓度相似，因此无法解释这些大脑区域之间的滋补抑制作用的差异。此外，我们的数据似乎暗示先前在海马和小脑中观察到的星形胶质细胞释放GABA的途径是Bestrophin-1以外的其他机制。