ORIGINAL ARTICLESEffect of D1-like and D2-like receptor antagonists on methamphetamine and 3,4-methylenedioxymethamphetamine self-administration in ratsBrennan, Katharine A.a b; Carati, Calebb; Lea, Rod A.a; Fitzmaurice, Paul S.a; Schenk, Susanb Author Information aInstitute of Environmental Science and Research Ltd., Porirua bSchool of Psychology, Victoria University of Wellington, Wellington, New Zealand Correspondence to Dr Katharine Alexandra Brennan, PhD, Victoria University, School of Psychology, PO Box 600, Wellington 6140, New Zealand E-mail: [email protected] Received 15 April 2009 Accepted as revised 24 August 2009 Behavioural Pharmacology: December 2009 - Volume 20 - Issue 8 - p 688-694 doi: 10.1097/FBP.0b013e328333a28d Buy Metrics Abstract It has been suggested that activation of dopamine D1-like and D2-like receptors contribute equally to the maintenance of drug self-administration. This study compared the contribution of these receptor subtypes to 3,4-methylenedioxymethamphetamine (MDMA) and methamphetamine (MA) self-administration. Effects of pretreatment with the D2-like receptor antagonist, eticlopride (0.0, 0.0125, 0.025 or 0.05 mg/kg, intraperitoneal), on responding maintained by several doses of MDMA (0.5, 1.0 and 2.0 mg/kg/infusion) and MA (0.05, 0.1 and 0.2 mg/kg/infusion) were determined. As we have published data showing the effects of the D1-like receptor antagonist, SCH23390 (0.0, 0.01 or 0.02 mg/kg, subcutaneous), on MDMA self-administration, effects of this dose range on the MA dose–response curve were determined. In our previous study, 0.02 mg/kg SCH23390 produced a rightward shift in the MDMA dose response curve, whereas in the present results, this dose decreased responding maintained by most doses of MA. Eticlopride increased the responding maintained by most doses of MDMA but failed to alter MA self-administration. The present results suggest that both D1-like and D2-like receptors contribute to the maintenance of MDMA self-administration, whereas MA self-administration was more sensitive to D1-like receptor blockade. © 2009 Lippincott Williams & Wilkins, Inc.