Fig. 1.

GABAR α1 and ErbB4 are widely coexpressed in the hippocampus, and ErbB4-null mice have diminished cortical α1 expression. Sections from 4-wk-old rat hippocampi were stained for the GABAR α1 subunit and ErbB4; nuclei were stained with DAPI. (A) High level of GABAR α1 and ErbB4 coexpression in CA1 interneurons. (Lower, individual channels of boxed area.) (B) Representative hilar dendrite showing a high degree of dendritic coexpression. (C) Enlarged boxed area of B, showing discrete overlapping puncta for GABAR α1 (C′) and ErbB4 (C′′) (arrowheads). (D) Interneuron soma showing perisomal colocalization (arrowheads) of GABAR α1 (D′) and ErbB4 (D′′). (Scale bars, 10 µm.) (E) Representative Western blot of cortical P2 membranes from wild-type and ErbB4^−/− mice; note the reduction in GABAR α1 in ErbB4^−/− mice. Quantification of GABAR α1 normalized to β-actin is shown (Right) (n = 4 individual experiments; *P < 0.05, paired t test).