The cannabinoid CB1 receptor is expressed on serotonergic and dopaminergic neurons

The endocannabinoid system is involved in memory, cognition, and pain perception by the presynaptic cannabinoid CB1 receptor, which is expressed at high levels in many brain regions. Functional studies have shown that activation of cannabinoid CB1 receptors inhibits the synaptic release of many neurotransmitters such as γ-aminobutyric acid, glutamate, acetylcholine and monoamines. Monoamines, however, are known not only to be released from and taken back up at nerve terminals but also at extrasynaptic axonal and somatodendritic sites. Here we present immunocytochemical data documenting cannabinoid CB1 receptor expression on neurite extensions and over cell bodies of serotonergic and dopaminergic neurons.