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Keywords:

  • Dopamine;
  • D3 receptors;
  • SB-277011A;
  • conditioned place aversion;
  • naloxone-induced withdrawal

Abstract

We examined the effect of SB-277011A, a selective D3 receptor antagonist, on the conditioned place aversion (CPA) response associated with naloxone-induced withdrawal from acute morphine administration in male Sprague-Dawley rats. Morphine (5.6 mg/kg i.p.) was given, followed 4 hrs later by naloxone (0.3 mg/kg i.p.) and prior to placing the animals in one specific chamber of the test apparatus. All animals were subjected to 2 of these trials. A significant CPA occurred in animals that received an i.p. injection of vehicle 30 minutes prior to the measurement of chamber preference. The pretreatment of animals (30 minutes prior to testing) with 3 mg/kg i.p. of SB-277011A did not significantly alter the CPA compared to animals treated with vehicle (1 ml/kg i.p. of deionized distilled water). In contrast, the acute pretreatment of animals with 6, 12 or 24 mg/kg i.p. of SB-277011A significantly decreased the CPA compared to vehicle-treated animals. In fact, the 12 and 24 mg/kg doses of SB-277011A significantly increased the time spent in the chamber where animals were paired with morphine and naloxone. These results suggest that the selective antagonism of D3 receptors attenuates the CPA produced by a model of naloxone-induced withdrawal from acute morphine dependence. Synapse, 2012. © 2011 Wiley Periodicals, Inc.