Molecular psychiatry
September 1, 2023
Kat F Kiilerich, Joe Lorenz, Malthe B Scharff et al.
48 citations
Repeated low doses of psilocybin, similar to human microdosing, were tested in rats. The regimen was well tolerated, causing no signs of anhedonia, anxiety, or altered movement, and did not downregulate or desensitize 5-HT2A receptors. The treatment increased resilience to injection stress, reduced self-grooming (a proxy for compulsive actions), and raised 5-HT7 receptor expression and synaptic density in the paraventricular nucleus of the thalamus. These findings support anecdotal reports of benefits from psilocybin microdosing and suggest a possible physiological mechanism.
Frontiers in pharmacology
January 1, 2023
Klemens Egger, Frederik Gudmundsen, Naja Støckel Jessen et al.
17 citations
Co-administration of harmine with DMT in rats increased brain DMT levels by inhibiting its metabolism to indole-3-acetic acid, yet no significant occupancy of serotonin 5-HT2A receptors by DMT was detected, even at brain DMT concentrations up to 11.3 µM. Low doses of DMT and/or harmine did not significantly alter brain glucose metabolism as measured by [18F]FDG-PET. These preliminary findings suggest that the role of MAO-A inhibition in potentiating DMT's psychedelic effects may be more complex than previously assumed, and further dose-response studies are needed.
January 5, 2023
Kat F. Kiilerich, Joe Lorenz, Malthe B. Scharff et al.
5 citations
preprint
Repeated low doses of psilocybin, a serotonergic psychedelic drug, were given to rats in a regimen that mimics human microdosing. The rats tolerated the doses well, showing no signs of anhedonia, anxiety, or altered movement. The treatment did not downregulate or desensitize the 5-HT2A receptor. It did impart resilience against stress from repeated injections and reduced self-grooming frequency, a proxy for compulsive actions. Additionally, it increased 5-HT7 receptor expression and synaptic density in the paraventricular nucleus of the thalamus. These findings support anecdotal reports of benefits from psilocybin microdosing and suggest a possible physiological mechanism.
May 28, 2024
Frederik Gudmundsen, Julia Czurylo, Camilla Trang Vo et al.
1 citation
preprint
Three serotonergic psychedelics—psilocybin, LSD, and 2C-B—produce distinct acute and long-term changes in rat brain metabolic activity and connectivity. Psilocybin uniquely alters connectivity between cortical regions including the orbitofrontal, medial prefrontal, and insula cortex, as well as with the dorsal striatum, thalamus, and hippocampus. LSD and 2C-B share more similar effects, centered on acute inhibition of the anterior cingulate cortex, increased activity and connectivity between the amygdala and hypothalamus, and heightened activity in dopamine-rich regions of the ventral tegmental area and substantia nigra. These distinct neural patterns may guide which psychedelic drug could be most beneficial for specific neuropsychiatric disorders.