Abstract
Rats trained to self-administer cocaine (0.75 mg/kg/infusion) on an FR-5 schedule were treated with selective D1 or D2 antagonists. A69045, a D1 antagonist with no appreciable affinity for 5-HT receptors increased cocaine self-administration to 147, 172 and 167% of baseline at doses of 2.5, 5.0 or 10.0 mumol/kg, SC respectively. SCH-23390 (0.007, 0.015 and 0.030 mumol/kg, SC) increased self-administration to 116, 147 and 165% of baseline, respectively. Both D1 antagonists decreased responding in some animals at the highest dose tested. The D2 antagonist YM-09151-2 showed a similar profile, increasing cocaine self-administration at 0.01 and 0.016 mumol/kg, SC and suppressing responding by most animals at the dose of 0.03 mumol/kg, SC. These data give further support to the hypothesis that both D1 and D2 receptors are involved in maintaining cocaine self-administration.
MeSH terms
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Animals
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Antipsychotic Agents / pharmacology
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Benzamides / pharmacology
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Benzazepines / pharmacology
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Cocaine / pharmacology*
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Corpus Striatum / drug effects
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Corpus Striatum / metabolism
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Dopamine Antagonists
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In Vitro Techniques
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Male
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Papaverine / analogs & derivatives*
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Papaverine / metabolism
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Papaverine / pharmacology
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Rats
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Rats, Inbred Strains
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Receptors, Adrenergic / drug effects
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Receptors, Adrenergic / metabolism
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Receptors, Dopamine / physiology*
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Receptors, Dopamine D1
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Receptors, Dopamine D2
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Receptors, Serotonin / drug effects
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Receptors, Serotonin / metabolism
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Reinforcement Schedule
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Self Administration / psychology
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Tetrahydroisoquinolines
Substances
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Antipsychotic Agents
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Benzamides
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Benzazepines
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Dopamine Antagonists
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Receptors, Adrenergic
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Receptors, Dopamine
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Receptors, Dopamine D1
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Receptors, Dopamine D2
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Receptors, Serotonin
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Tetrahydroisoquinolines
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A 69024
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Papaverine
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Cocaine
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nemonapride