[Role of endogenous cannabinoids in cerebral reward mechanisms].

Central cannabinoid receptors (CB1 receptors) are densely located in the output nuclei of the basal ganglia (globus pallidus, substantia nigra pars reticulata). Endogenous cannabinoids appear to modulate transmitter systems (e.g. dopamine) within the basal ganglia. In the striatum, CB1 receptors are localized on the same neurons as Gi-coupled dopamine D2 receptors. Striatal CB1 receptors are also negatively linked to adenylcyase, and may modulate dopamine release. The presence of CB1 receptors in dopaminergic neurons strongly suggests that cannabinoids play a modulatory role in dopaminergic neuronal pathways. This co-localization may postulate "cross talk" between endocannabinoids and dopamine-dependent reward mechanisms.