Psychopharmacology

, Volume 197, Issue 3, pp 443–448

The role of beta-endorphin in the acute motor stimulatory and rewarding actions of cocaine in mice

  • Paul Marquez
  • Ramkumarie Baliram
  • Ibrahim Dabaja
  • Nagaraju Gajawada
  • Kabirullah Lutfy
Original Investigation

DOI: 10.1007/s00213-007-1053-z

Cite this article as:
Marquez, P., Baliram, R., Dabaja, I. et al. Psychopharmacology (2008) 197: 443. doi:10.1007/s00213-007-1053-z

Abstract

Rationale

Opioid receptor antagonists have been shown to attenuate the rewarding and addictive effects of cocaine. Furthermore, cocaine has been shown to cause the release of beta-endorphin, an endogenous opioid peptide.

Objective

We assessed whether this neuropeptide would play a functional role in cocaine-induced motor stimulation and conditioned place preference (CPP).

Materials and methods

Mice lacking beta-endorphin and their wild-type littermates were habituated to motor activity chambers for 1 h, then injected with cocaine (0, 15, 30, or 60 mg/kg, intraperitoneally) or morphine (0, 5, or 10 mg/kg, subcutaneously), and motor activity was recorded for 1 h. In the CPP paradigm, mice were tested for baseline place preference on day 1. On days 2 and 3, mice received an alternate-day saline/cocaine (15, 30, or 60 mg/kg) or saline/morphine (10 mg/kg) conditioning session and then tested for postconditioning place preference on day 4.

Results

Cocaine-induced motor stimulation and CPP were both reduced in mice lacking beta-endorphin. On the other hand, motor stimulation and CPP induced by morphine were not altered in mutant mice.

Conclusion

The present results demonstrate that the endogenous opioid peptide beta-endorphin plays a modulatory role in the motor stimulatory and rewarding actions of acute cocaine.

Keywords

CocaineMorphineMotor activityConditioned place preferenceRewardbeta-EndorphinProopiomelanocortinKnockout mouse

Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • Paul Marquez
    • 1
  • Ramkumarie Baliram
    • 1
    • 2
  • Ibrahim Dabaja
    • 1
  • Nagaraju Gajawada
    • 1
  • Kabirullah Lutfy
    • 1
  1. 1.Department of Pharmaceutical Sciences, College of PharmacyWestern University of Health SciencesPomonaUSA
  2. 2.Mount Sinai School of MedicineNew YorkUSA