Psychedelic effects of psilocybin correlate with serotonin 2A receptor occupancy and plasma psilocin levels
- PMID: 30685771
- PMCID: PMC6785028
- DOI: 10.1038/s41386-019-0324-9
Psychedelic effects of psilocybin correlate with serotonin 2A receptor occupancy and plasma psilocin levels
Erratum in
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Correction: Psychedelic effects of psilocybin correlate with serotonin 2A receptor occupancy and plasma psilocin levels.Neuropsychopharmacology. 2019 Jun;44(7):1336-1337. doi: 10.1038/s41386-019-0360-5. Neuropsychopharmacology. 2019. PMID: 30846853 Free PMC article.
Abstract
The main psychedelic component of magic mushrooms is psilocybin, which shows promise as a treatment for depression and other mental disorders. Psychedelic effects are believed to emerge through stimulation of serotonin 2A receptors (5-HT2ARs) by psilocybin's active metabolite, psilocin. We here report for the first time the relationship between intensity of psychedelic effects, cerebral 5-HT2AR occupancy and plasma levels of psilocin in humans. Eight healthy volunteers underwent positron emission tomography (PET) scans with the 5-HT2AR agonist radioligand [11C]Cimbi-36: one at baseline and one or two additional scans on the same day after a single oral intake of psilocybin (3-30 mg). 5-HT2AR occupancy was calculated as the percent change in cerebral 5-HT2AR binding relative to baseline. Subjective psychedelic intensity and plasma psilocin levels were measured during the scans. Relations between subjective intensity, 5-HT2AR occupancy, and plasma psilocin levels were modeled using non-linear regression. Psilocybin intake resulted in dose-related 5-HT2AR occupancies up to 72%; plasma psilocin levels and 5-HT2AR occupancy conformed to a single-site binding model. Subjective intensity was correlated with both 5-HT2AR occupancy and psilocin levels as well as questionnaire scores. We report for the first time that intake of psilocybin leads to significant 5-HT2AR occupancy in the human brain, and that both psilocin plasma levels and 5-HT2AR occupancy are closely associated with subjective intensity ratings, strongly supporting that stimulation of 5-HT2AR is a key determinant for the psychedelic experience. Important for clinical studies, psilocin time-concentration curves varied but psilocin levels were closely associated with psychedelic experience.
Conflict of interest statement
The authors declare no competing interests.
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