John J Panos1, Lisa E Baker. 1. Department of Psychology, Western Michigan University, Kalamazoo, MI 49008, USA.
Abstract
BACKGROUND AND RATIONALE: Despite the popularity of polysubstance abuse among recreational methylendioxymethamphetamine (MDMA) users, relatively few controlled experimental studies have documented the neurobehavioral effects of MDMA in combination with other abused substances. OBJECTIVE: In this study, the combined acute effects of MDMA and cocaine were examined by conducting in vivo microdialysis in the rat nucleus accumbens while simultaneously monitoring locomotor activity. METHODS: Male Sprague-Dawley rats were administered cocaine (10 or 20 mg/kg, i.p.), MDMA (1.5 or 3.0 mg/kg, i.p.), or one of four combinations of cocaine and MDMA during microdialysis experiments. Locomotor activity was monitored, and dialysis samples were collected every 30 min for 3 h prior to injections, for one 30-min period following saline injections, and for an additional 3-h period following drug injections. Samples were analyzed for dopamine content by high-performance liquid chromatography with electrochemical detection. RESULTS: Significant differences in locomotor activity and dopamine efflux were found among treatment groups, with some MDMA/cocaine combinations producing significantly greater increases compared to single doses of cocaine or MDMA within the first 30 min after injection. CONCLUSION: Considering the popularity of polysubstance use among recreational MDMA users, the clinical implications of the current findings warrant further investigation.
BACKGROUND AND RATIONALE: Despite the popularity of polysubstance abuse among recreational methylendioxymethamphetamine (MDMA) users, relatively few controlled experimental studies have documented the neurobehavioral effects of MDMA in combination with other abused substances. OBJECTIVE: In this study, the combined acute effects of MDMA and cocaine were examined by conducting in vivo microdialysis in the rat nucleus accumbens while simultaneously monitoring locomotor activity. METHODS: Male Sprague-Dawley rats were administered cocaine (10 or 20 mg/kg, i.p.), MDMA (1.5 or 3.0 mg/kg, i.p.), or one of four combinations of cocaine and MDMA during microdialysis experiments. Locomotor activity was monitored, and dialysis samples were collected every 30 min for 3 h prior to injections, for one 30-min period following saline injections, and for an additional 3-h period following drug injections. Samples were analyzed for dopamine content by high-performance liquid chromatography with electrochemical detection. RESULTS: Significant differences in locomotor activity and dopamine efflux were found among treatment groups, with some MDMA/cocaine combinations producing significantly greater increases compared to single doses of cocaine or MDMA within the first 30 min after injection. CONCLUSION: Considering the popularity of polysubstance use among recreational MDMA users, the clinical implications of the current findings warrant further investigation.
Authors: Jason M Wiebelhaus; Travis W Grim; Robert A Owens; Matthew F Lazenka; Laura J Sim-Selley; Rehab A Abdullah; Micah J Niphakis; Robert E Vann; Benjamin F Cravatt; Jenny L Wiley; S Stevens Negus; Aron H Lichtman Journal: J Pharmacol Exp Ther Date: 2014-11-14 Impact factor: 4.030