Figure 2.

Topographic distribution of GFP immunofluorescence in the NAc of Drd2-EGFP mice. (A) Distribution of GFP in the NAc of Drd2-EGFP BAC transgenic mice. Single confocal sections were stitched together as a single image. Scale bar: 500 μm. DStr, dorsal striatum; aca, anterior commissure; Tu, olfactory tubercles. (B) Schematic illustration of the different accumbal subterritories analyzed (see Figure A1). Cyan in the diagram represents distribution of GFP-expressing cells. A zone homogenously cyan means the GFP is homogenously distributed. White means lack of GFP expression throughout the zone and dots indicate that few GFP cells are detected throughout the zone. Note that D2R-expressing MSNs exhibit inhomogeneous distributions in the NAc shell. In the caudomedial NAc shell (1) a bundle-shaped area and (2) a D2R-expressing MSNs-poor zones (white) in the upper part of the caudomedial shell (cyan) can be visualized. In the ventral shell, two zones lacking D2R-expressing MSNs (white) can be delineated. Single scan confocal images stained for GFP (cyan) and DARPP-32 (red), a marker of MSNs, in the dorsal caudomedial (GFP, B₁; DARPP-32, B₂; merge, B₃) and ventral (GFP, B₄; DARPP-32, B₅; merge, B₆) part of the shell of Drd2-EGFP mice. Images shown are representative of all Drd2-EGFP BAC transgenic mice analyzed (n = 5). Yellow asterisk identifies the D2R-expressing MSNs-poor zone. Yellow arrowheads identify the bundle-shaped area. Scale bar: 200 μm.