Dopamine and serotonin antagonists fail to alter the discriminative stimulus properties of ±methylenedioxymethamphetamine

This study aimed to determine effects of selective dopamine (DA) and serotonin (5HT) antagonists on the discriminative stimulus properties of AMPH (0.5 mg/kg) and MDMA (3.0 mg/kg). Separate groups of rats were trained to discriminate AMPH (0.5 mg/kg) or MDMA (3.0 mg/kg) from saline using a food-reinforced drug-discrimination procedure. Effects of DA (SCH 23390: 0.003–0.03 mg/kg and eticlopride: 0.03–0.3 mg/kg) or 5HT (ritanserin: 1.0–10.0 mg/kg, WAY-100635: 0.3–1.0 mg/kg and GR129375: 1.0–3.0 mg/kg) antagonists on the discriminative stimulus effects of both drugs were determined. Both DA antagonists dose-dependently decreased the AMPH but not the MDMA discrimination. None of the 5HT antagonists altered the discriminative stimulus effects of either drug. The MDMA (3.0 mg/kg) stimulus comprises both a DAergic and 5HTergic response, and the results suggest that either one is sufficient, but not required, to maintain the stimulus effects.
Source: Behavioural Pharmacology - Category: Drugs & Pharmacology Tags: RESEARCH REPORTS Source Type: research