Discriminative stimulus properties of 7-OH-DPAT, a dopamine D3-selective receptor ligand.

7-Hydroxy-N,N-di-n-propyl-2-aminotetralin (7-OH-DPAT) is a high affinity and selective ligand at dopamine D3 receptors. Rats were trained to discriminate 7-OH-DPAT (0.05 mg/kg) from drug vehicle using a food-reinforced (FR 10) two-lever operant procedure. Six out of nine rats learned to discriminate 7-OH-DPAT, requiring a mean of 29 training sessions. After the training dose was increased to 0.10 mg/kg the remaining three rats reached discrimination performance criterion. The 7-OH-DPAT stimulus was dose-dependent. Doses of 0.01, 0.03, 0.056, and 0.1 mg/kg 7-OH-DPAT produced 0, 11, 78, and 100% drug-correct lever selection, respectively, with the ED50 value calculated to be 0.038 mg/kg. These results demonstrate that the D3-selective ligand 7-OH-DPAT can control differential operant responding in rats on the basis of its discriminative stimulus properties.