A Brain on Cannabinoids: The Role of Dopamine Release in Reward Seeking

Increases in mesolimbic dopamine transmission are observedwhen animals are treatedwith all known drugs of abuse, including cannabis, and to conditioned stimuli predicting their availability. In contrast, decreases in mesolimbic dopamine function are observed during drug withdrawal, including cannabis-withdrawal syndrome. Thus, despite general miscon-ceptions that cannabis is unique from other drugs of abuse, cannabis exerts identical effects on the mesolimbic dopamine system. The recent discovery that endogenous cannabinoids modulate the mesolimbic dopamine system, however, might be exploited for the develop-ment of potential pharmacotherapies designed to treat disorders of motivation. Indeed, disrupting endocannabinoid signaling decreases drug-induced increases in dopamine release in addition to dopamine concentrations evoked by conditioned stimuli during reward seeking. All known drugs of abuse, including D 9-tet-rahydrocannabinol, the primary psychoac-tive component of Cannabis sativa, increas