Cannabinoid receptor antagonist reduces heroin self-administration only in dependent rats

Functionality of the endogenous cannabinoid system undergoes relevant changes in reward-related brain areas in animal models of opiate addiction. By using a limited access heroin self-administration paradigm we show that cannabinoid CB, receptor antagonist N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide hydrochloride (SR141716A, 0.03-3.0 mg/ kg) suppresses heroin self-administration only in opiate-dependent rats but not in non-dependent animals. These results further support the study of cannabinoid CB1 receptor antagonists for the treatment of opiate addiction. (C) 2004 Published by Elsevier B.V.