5-HT2A Receptor
A subtype of serotonin receptor and the primary target of classical psychedelics including psilocin.
The 5-HT2A receptor is a subtype of serotonin receptor found throughout the brain, particularly in cortical regions associated with sensory integration, attention, and self-referential processing. It is the primary molecular target of psilocin and other classical psychedelics including LSD, DMT, and mescaline.
When psilocin binds to 5-HT2A receptors, it acts as a partial agonist — meaning it activates the receptor in a way that differs from the natural ligand, serotonin. This activation triggers downstream effects on cortical glutamate release, dendritic activity, and large-scale brain network organization.
Notably, the subjective intensity of psilocybin experiences correlates with 5-HT2A receptor occupancy. Selective 5-HT2A antagonists administered before psilocybin almost entirely block the psychedelic effects, confirming this receptor as the principal site of action.