, Volume 125, Issue 1, pp 13–22

Self-administration of the dopamine D3 agonist 7-OH-DPAT in rhesus monkeys is modified by prior cocaine exposure

  • M. A. Nader
  • R. H. Mach
Original Investigation

DOI: 10.1007/BF02247388

Cite this article as:
Nader, M.A. & Mach, R.H. Psychopharmacology (1996) 125: 13. doi:10.1007/BF02247388


Cocaine self-administration was compared with responding maintained by the dopamine D3 agonist 7-hydroxy-N,N-di-n-propyl-2-aminotetralin (7-OH-DPAT) in rhesus monkeys. In the first experiment, monkeys (n=3) with an extensive cocaine history responded under a fixed-interval (FI) 5-min schedule of IV cocaine (0.03 mg/kg per injection) presentation, during daily 4-h sessions. When responding was stable, dose-response curves were determined for cocaine (0.01-0.3 mg/kg per injection) and 7-OH-DPAT (0,001–0.1 mg/kg per injection); each dose was available for at least five consecutive sessions. When substituted for the baseline dose of cocaine, other doses of cocaine and 7-OH-DPAT maintained rates higher than responding maintained by saline injections, in all monkeys. 7-OH-DPAT maintained response rates equal to or higher than rates of cocainemaintained responding in all monkeys. In a second experiment, acquisition of 7-OH-DPAT self-administration was evaluated in a group of cocaine-navie monkeys (n=3). Various doses of 7-OH-DPAT (0.003–0.03 mg/kg during daily 4-h sessions. After 10–13 sessions, 7-OH-DPAT self-administration could not be trained in any cocaine-naive monkey. When cocaine was made available to these monkeys, responding was reliably maintained within one to four sessions and the schedule was gradually increased to FI 5-min. After stable responding under an FI 5-min schedule of 0.03 mg/kg per injection cocaine presentation, 7-OH-DPAT (0.01 mg/kg per injection) was again made available to two of the monkeys, and maintained responding at rates higher than saline. To determine better whether a history of responding maintained by another reinforcer would result in high rates of 7-OH-DPAT self-administration, two cocaine-naive monkeys were trained to respond under an FI 5-min schedule of food presentation. Substituting 7-OH-DOAT (0.003–0.03 mg/kg per injection) for food resulted in very low rates of responding. Taken together, these results suggest that despite comparable reinforcing effects in cocaine-substitution studies, 7-OH-DPAT and cocaine differ in their rate of acquisition, perhaps indicating a lower abuse liability for 7-OH-DPAT.

Key words

Cocaine7-OH-DPATSelf-administrationDopamine receptorsExperimental historyRhesus monkey

Copyright information

© Springer-Verlag 1996

Authors and Affiliations

  • M. A. Nader
    • 1
    • 2
  • R. H. Mach
    • 1
    • 3
  1. 1.Department of Physiology and Pharmacology, Bowman Gray School of MedicineWake Forest UniversityWinston-SalemUSA
  2. 2.Department of Comparative Medicine, Bowman Gray School of MedicineWake Forest UniversityWinston-SalemUSA
  3. 3.Department of Radiology, PET Center, Bowman Gray School of MedicineWake Forest UniversityWinston-SalemUSA