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The relative contribution of dopamine receptor subtypes to the discriminative stimulus effects of cocaine in free‐feeding and food‐restricted rats
Author(s) -
Baladi Michelle G,
France Charles P
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.795.13
Feeding condition can impact the role of dopamine (DA) receptor subtypes in the behavioral effects of direct‐acting DA receptor agonists but less is known regarding indirect‐acting DA receptor agonists. In the current study, free‐feeding and food‐restricted male Sprague Dawley rats (n=6/group) were trained to discriminate cocaine (10 mg/kg) from saline under a schedule of stimulus shock termination. Stimulus control was established after an average of 42 +/− 4 and 32 +/− 7 training sessions in free‐feeding and food‐restricted rats, respectively. Regardless of feeding condition, cocaine and amphetamine occasioned responding predominantly on the cocaine‐associated lever. However, the direct‐acting DA receptor agonists, lisuride and quinpirole, occasioned responding predominantly on the cocaine‐associated lever in free‐feeding rats, and much less responding on the cocaine‐associated lever in food‐restricted rats. A D2 receptor antagonist, L‐741,626, did not significantly modify the cocaine dose‐response curve in either group of rats while a D3 receptor antagonist, PG01037, shifted the dose‐response curve to the right in free‐feeding but not food‐restricted rats. These results suggest that in free‐feeding rats, D3 receptors have a greater contribution than D2 receptors to the discriminative stimulus effects of cocaine. CPF is supported by Senior Scientist Award DA17918.