INVESTIGATIONS INTO THE NATURE OF A 7-OH-DPAT DISCRIMINATIVE CUE - COMPARISON WITH D-AMPHETAMINE

In the present study, separate squads of rats were trained to discrimi nate either the dopamine D-3 receptor preferring ligand 7-hydroxy-2-(d i-N-propylamino)-tetralin (7-OH-DPAT) (0.03 mg/kg) from saline, or D-a mphetamine (0.3 mg/kg) from saline using a standard operant schedule ( FR10 schedule reinforcement). Following stable acquisition of respondi ng, tests of generalisation and antagonism were conducted. A number of dopamine agonists having high dopamine D-2-like receptor (D-2, D-3 or D-4) affinity generalised to the 7-OH-DPAT, but not amphetamine, cue. The dopamine D-1/5 receptor agonist SKF38393 showed no generalisation to either drug cue. Subsequent correlational analysis suggested that this effect was most likely mediated through the dopamine D-3 receptor . The dopamine D-2/3 receptor antagonist raclopride significantly atte nuated both cues. The failure of these drugs to generalise to amphetam ine, suggest that there is little involvement of the dopamine D-3 rece ptor subtype in mediating its discriminative stimulus properties. (C) 1997 Elsevier Science B.V.