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Chronic d‐amphetamine alters food‐reinforced responding and cocaine self‐administration under a progressive‐ratio schedule in rhesus monkeys
Author(s) -
Czoty Paul W,
Martelle Jennifer L,
Garrett Nicholas R,
Nader Michael A
Publication year - 2008
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.22.1_supplement.713.14
Subject(s) - self administration , amphetamine , dextroamphetamine , medicine , food delivery , anesthesia , pharmacology , dopamine , marketing , business
d‐Amphetamine (AMPH) decreases cocaine self‐administration (SA) in laboratory animals, and reduces cocaine use in humans. In these studies, effects of chronic AMPH were examined in four rhesus monkeys responding under a progressive‐ratio (PR) schedule of cocaine injection. Each day, 1‐g food pellets were available under a fixed‐ratio 50 schedule starting at 8am for 23 h or until the day's food ration was earned. On another lever, cocaine (0.003–0.56 mg/kg/inj) was available under a PR schedule from 3pm until 2 h passed without an injection. Cocaine access was suspended and AMPH (0.01–0.1 mg/kg/hr, i.v.) was administered by continuous infusion for 5 days. Dose‐related reductions in food‐reinforced responding were observed during AMPH treatment that dissipated when AMPH administration was discontinued. Dose‐related reductions in the reinforcing strength of 0.03 mg/kg/inj cocaine were observed when cocaine was made available starting the day after AMPH treatment, but not when a 6‐day washout period intervened; effects were similar when treatment with a low dose of AMPH was extended to 12 days. Importantly, AMPH‐induced reductions in food‐maintained responding recovered faster than AMPH‐induced decreases in cocaine SA. Ongoing experiments are assessing whether longer durations of AMPH treatment lead to more persistent reductions in cocaine SA. Support: DA 06634.