, Volume 112, Issue 1, pp 93–99 | Cite as

Modification of behavioral effects of cocaine by selective serotonin and dopamine uptake inhibitors in squirrel monkeys

  • R. D. Spealman
Original Investigations


Modification of the behavioral effects of cocaine by the selective serotonin (5-HT) uptake inhibitors citalopram and fluoxetine and the selective dopamine (DA) uptake inhibitor GBR 12909 was investigated in squirrel monkeys trained under a fixed-interval schedule of reinforcement or a two-lever cocaine-discrimination procedure. Under the fixed-interval schedule cocaine (0.03–1.78 mg/kg) produced dose-related increases in response rate, reaching an average maximum of 215% of control after a dose of 0.3 mg/kg. Similar rate-increasing effects were seen with GBR 12909 (3.0 or 10.0 mg/kg), but not citalopram (10.0 or 17.8 mg/kg) or fluoxetine (10.0 mg/kg). Pretreatment with citalopram or fluoxetine attenuated the rate-increasing effects of cocaine and produced an overall downward shift in the cocaine dose-response function. Pretreatment with GBR 12909, on the other hand, produced an overall leftward shift in the cocaine dose-response function. Under the drug-discrimination procedure cocaine (0.03–1.78 mg/kg) engendered dose-related increases in the percentage of cocaine-appropriate responses, as did GBR 12909 (1.0–17.8 mg/kg) but not citalopram (1.0–17.8 mg/kg). Pretreatment with citalopram attenuated the discriminative stimulus effects of cocaine and produced an overall rightward shift in the cocaine dose-response function, whereas pretreatment with GBR 12909 produced an overall leftward shift in the cocaine dose-response function. The results show that selective 5-HT and DA uptake inhibitors can modify the rate-altering and discriminative stimulus effects of cocaine in qualitatively different ways and suggest a modulatory role for 5-HT uptake inhibition in the behavioral effects of cocaine.

Key words

Cocaine Drug discrimination Schedule-controlled behavior Serotonin uptake inhibitors Dopamine uptake inhibitors Squirrel monkeys 


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Copyright information

© Springer-Verlag 1993

Authors and Affiliations

  • R. D. Spealman
    • 1
  1. 1.Harvard Medical School, New England Regional Primate Research CenterSouthboroughUSA

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