Fig. 3.

Selective gene induction in D₁-receptor-bearing striatal neurons. Double-labelin situ hybridization was performed with probes to the gene ania-4 (silver grains) and either D₁receptor (A) or enkephalin (B). The field in each case is taken from a brain section treated as in Figure 2 (i.e., 2 hr after SKF38393, 5 mg/kg), with additional hybridizations using digoxygenin-labeled probes, visualized by a dark reaction product. A, Induced ania-4 mRNA colocalizes with D₁ receptor mRNA. B, Induced ania-4 mRNA does not colocalize with mRNA for enkephalin, a marker of D₂-receptor-bearing striatopallidal neurons. Scale bars, ∼50 μm.