, Volume 197, Issue 3, pp 443-448
Date: 06 Jan 2008

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

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access



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.


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.


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.


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.