Serotonin 1A receptor (5-HT1A)

The serotonin 1A receptor, or 5-HT1A, is a receptor for serotonin found throughout the brain that lowers neuronal firing and is a target of several anxiety and depression medicines.

5-HT1A receptors sit in two places. On serotonin-producing neurons in the raphe nuclei they act as autoreceptors, sensing serotonin and slowing its further release; on neurons in the hippocampus, cortex and amygdala they act as postsynaptic receptors that make those cells less excitable. Both actions are inhibitory, mediated through G proteins that open potassium channels and lower cyclic AMP. The anxiety medicine buspirone is a 5-HT1A partial agonist, and the delayed onset of SSRIs is partly explained by the gradual desensitization of raphe autoreceptors.

The receptor appears in cannabinoid discussions because CBD has been shown in laboratory studies to act as an agonist or positive modulator at 5-HT1A, and rodent experiments that block the receptor also block some of CBD's observed effects. This is a proposed mechanism behind the anxiety-related findings reported in early human studies of CBD; it remains under investigation and is not an established clinical action.