D1-like and D2 dopamine receptor antagonists administered into the shell subregion of the rat nucleus accumbens decrease cocaine, but not food, reinforcement.
Cocaine self-administration experiments were designed to assess the respective roles of D1-like and D2-like dopamine receptors in the ventral forebrain in cocaine reinforcement. D1-like or D2-like dopamine receptor antagonists were microinjected into the nucleus accumbens core, nucleus accumbens shell, neostriatum or lateral septum prior to sessions in which cocaine was self-administered under a progressive ratio schedule by rats. The results indicated that administration of a D1/5 (SCH-23390) or a D2/D3/D4 (eticlopride), but not a D3 (U99194A) or D4 (L-750,667), dopamine receptor antagonist into the core and shell of the nucleus accumbens decreased the reinforcing efficacy of cocaine. However, in control experiments intra-accumbal core administration of SCH-23390 or eticlopride decreased food self-administration, whereas administration of these drugs into the accumbens shell had no effect on food reinforcement. Neither SCH-23390 nor eticlopride influenced cocaine reinforcement when administered into the neostriatum or lateral septum. Collectively, these results indicate that D1-like and D2 dopamine receptors in the nucleus accumbens shell selectively modulate the reinforcing efficacy of cocaine, whereas D1-like and D2 dopamine receptors in the accumbens core have a more general influence on reinforced behaviors.
Bari
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Laboratory of Neuropsychopharmacology, Department of Pharmacology, L-603, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118, USA.
Pierce
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RC
D000818:Animals; D001552:Benzazepines / Q000008:administration & dosage / Q000494:pharmacology; D003042:Cocaine / Q000008:administration & dosage / Q000037:antagonists & inhibitors* / Q000494:pharmacology*; D003216:Conditioning, Operant / Q000187:drug effects; D018492:Dopamine Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D065127:Dopamine D2 Receptor Antagonists; D004305:Dose-Response Relationship, Drug; D005502:Food; D007275:Injections, Intravenous; D008297:Male; D008845:Microinjections; D009714:Nucleus Accumbens / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017447:Receptors, Dopamine D1 / Q000037:antagonists & inhibitors*; D050637:Receptors, Dopamine D3 / Q000037:antagonists & inhibitors; D050638:Receptors, Dopamine D4 / Q000037:antagonists & inhibitors; D050641:Receptors, Dopamine D5 / Q000037:antagonists & inhibitors; D012054:Reinforcement, Psychology; D012457:Salicylamides / Q000008:administration & dosage / Q000494:pharmacology; D012646:Self Administration
D001552:Benzazepines; D018492:Dopamine Antagonists; D065127:Dopamine D2 Receptor Antagonists; D017447:Receptors, Dopamine D1; D050637:Receptors, Dopamine D3; D012457:Salicylamides; D050638:Receptors, Dopamine D4; D050641:Receptors, Dopamine D5; D003042:Cocaine; C045989:eticlopride