Role of dopamine receptor subtypes in the acquisition of a testosterone conditioned place preference in rats.

The present experiments investigated the neurochemical bases of the rewarding properties of testosterone, focusing on the role of dopaminergic function in the acquisition of a testosterone conditioned place preference (CPP). In two experiments for 8 alternating days adult male Long-Evans rats received peripheral injections of testosterone in a water-soluble hydroxypropyl-beta-cyclodextrin inclusion complex (0.8 mg/kg) or saline immediately prior to being confined for 30 min to one of two compartments of a place preference apparatus. On day 10 the rats were given a 20-min test session and allowed access to all compartments of the apparatus. No hormone was injected prior to the test, and the amount of time spent in each compartment of the apparatus was recorded. In each experiment administration of testosterone was found to induce a CPP. Injections of the mixed D1/D2 receptor antagonist alpha-flupenthixol (0.3 mg/kg), the selective D1 antagonist SCH 23390 (0.1 mg/kg), or the selective D2 antagonist sulpiride (20 mg/kg), each blocked acquisition of the testosterone CPP. The findings suggest a role for both dopamine D1 and D2 receptor subtypes in the acquisition of testosterone CPP.