Figure 13.

Topographical and cell-type specific regulation of P-ERK by cocaine and d-amphetamine in the NAc. (A–F) Quantification of P-ERK positive cells among GFP-negative (white bars) and GFP-positive (green bars) neurons in the NAc core (A), in the ventral NAc shell [(B) D2R-expressing MSNs-poor zone and (C) area surrounding the D2R-expressing MSNs-poor zone] and in the caudomedial NAc shell [(D) bundle-shaped area; (E) D2R-expressing MSNs-poor zone; and (F) cone] in Drd2-EGFP mice, 15 min after vehicle (Veh), cocaine (Coc), and d-amphetamine (d-amph) administration. Note that cocaine- and d-amphetamine-induced ERK activation is restricted to D1R-expressing MSNs. Yellow asterisk indicates the D2R-expressing MSNs-poor zone. Green squares in diagrams indicate the region analyzed. Data are number of cells per area (see Table A2) and are expressed as means ± SEM (4–5) and were analyzed using one-way ANOVA (see Table A3 for F values). Dunnett's test: ^*p < 0.05, ^**p < 0.01, ^***p < 0.001 veh vs. drugs in Drd2-EGFP negative. (G) Double immunofluorescence for P-ERK (magenta) and GFP (green) in various subterritories of the NAc shell in Drd2-EGFP mice treated with vehicle, cocaine (15 mg/kg) and d-amphetamine (10 mg/kg). Images are single confocal sections. Scale bar: 100 μm.