Psychedelic effects of psilocybin correlate with serotonin 2A receptor occupancy and plasma psilocin levels
Neuropsychopharmacology January 26, 2019 M. Madsen, Patrick M. Fisher, Daniel Burmester et al. 505 citations
Psilocybin, the main psychedelic component of magic mushrooms, produces its effects by activating serotonin 2A receptors in the brain. In eight healthy volunteers who received a single oral dose of psilocybin (3–30 mg), PET scans showed dose-related occupancy of these receptors up to 72%. Plasma levels of psilocin, the active metabolite, and receptor occupancy both closely matched subjective ratings of psychedelic intensity, supporting that stimulation of serotonin 2A receptors is a key determinant of the psychedelic experience. Although psilocin levels in the blood varied over time, they were strongly linked to the intensity of the experience, which is important for designing clinical studies.