Immunoreactivity for GABA, GAD65, GAD67 and Bestrophin-1 in the Meninges and the Choroid Plexus: Implications for Non-Neuronal Sources for GABA in the Developing Mouse Brain
Figure 2
GAD65/67 expression in the meninges and the presence of GABA beneath the meninges.
(A) Double immunolabeling for GAD65/67 (Green) and Laminin (Red) in the E14.5 neocortical primordium. The signals for GAD65/67 were present along the basal lamina which is laminin-positive (arrow). (B) Double immunostaining for GAD65/67 (green) and pan-Zic proteins (Red) in the E14.5 neocortex. Most of the cells expressing GAD65/67 also express Zic proteins, which are the transcriptional factors working as the markers of the meningeal fibroblasts (arrowheads), although, to be noted, a few GAD65/67-positve cells do not express Zic proteins (arrow). A few Cajal-Retzius cells in the marginal zone (MZ) express Zic proteins (asterisks). (C) Immunostaining for GABA in the upper layers of developing neocortex. GABA signals could be observed at the upper edge of the E14.5 developing neocortex just beneath the meninge (arrows). GABA-containing neurons in the marginal zone and in the subplate are also visualized (several representatives are indicated by arrowheads). The counterstaining by 7-amino-actinomycin D (7-AAD) helps to visualize the contours and the density of the cells in the developing cortical layers. (D) The E14.5 sections stained for GAD65/67 and Rdh10, an RA-synthesizing enzyme. RA is known to be released from the meningeal fibroblasts [11]. The signals for both proteins were present in the meninges (arrows). Me, meninge; MZ, marginal zone; CP, cortical plate; SP, subplate. Bars, 50 µm.