Archives of General Psychiatry
September 7, 2010
Gurpreet S Chopra, Marycie Hagerty, Charles S. Grob et al.
1,220 citations
In a double-blind, placebo-controlled study, twelve adults with advanced-stage cancer and anxiety received a moderate dose (0.2 mg/kg) of psilocybin. Safe physiological and psychological responses were documented, with no clinically significant adverse events. The State-Trait Anxiety Inventory trait anxiety subscale showed a significant reduction in anxiety at 1 and 3 months after treatment. The Beck Depression Inventory indicated improved mood that reached significance at 6 months; the Profile of Mood States showed mood improvement that approached but did not reach significance. The results support the need for more research into psilocybin for cancer-related anxiety.
Journal of Psychopharmacology
December 8, 2010
Liselore Koedood, Adam L. Halberstadt, Susan B. Powell et al.
212 citations
Psilocin, the active metabolite of psilocybin, acts as an agonist at 5-HT1A, 5-HT2A, and 5-HT2C receptors. In mice, psilocin induced head twitch response (HTR) via 5-HT2A receptors, as effects were absent in mice lacking that gene. In the behavioral pattern monitor (BPM), psilocin decreased locomotor activity, holepoking, and time in the chamber center; these effects were blocked by the 5-HT1A antagonist WAY-100635 but not by 5-HT2C antagonism or 5-HT2A gene deletion. 5-MeO-DMT produced similar BPM effects attenuated by WAY-100635. Psilocin and 5-MeO-DMT decreased path linearity via 5-HT2C and 5-HT1A receptors, respectively. 1-methylpsilocin induced HTR via 5-HT2A but was inactive in the BPM, suggesting greater pharmacological selectivity and potential as a therapeutic alternative to psilocybin.
Nat Commun
December 15, 2023
Jason Wallach, Andrew B. Cao, Maggie M. Calkins et al.
153 citations
Serotonergic psychedelics show therapeutic potential, but the specific roles of 5-HT2A receptor signaling pathways are unclear. Researchers developed selective ligands with varying Gq efficacies, including β-arrestin-biased ones. In male mice, 5-HT2A-Gq recruitment efficacy, not β-arrestin2 recruitment, predicted psychedelic potential measured by head-twitch response magnitude. Disrupting Gq-PLC signaling reduced this response, and a threshold Gq activation level was needed for psychedelic-like effects, explaining why partial agonists like lisuride are non-psychedelic. β-arrestin-biased agonists blocked psychedelic effects and caused receptor downregulation and tachyphylaxis. Fine-tuning 5-HT2A Gq-signaling enables development of non-psychedelic 5-HT2A agonists.
Neuropharmacology
February 1, 2014
Adam L. Halberstadt, Mark A. Geyer
113 citations
N-benzyl substitution greatly increases the potency of phenethylamine hallucinogens at the 5-HT(2A) receptor. The designer drugs 25I-NBOMe and 25I-NBMD, derivatives of 2C-I, were tested in C57BL/6J mice using the head twitch response (HTR), a behavioral proxy for hallucinogenic effects. 2C-I (1-10 mg/kg), 25I-NBOMe (0.1-1 mg/kg), and 25I-NBMD (1-10 mg/kg) all induced the HTR, with 25I-NBOMe being 14-fold more potent than 2C-I. The selective 5-HT(2A) antagonist M100,907 completely blocked the HTR for all compounds, confirming that these effects are mediated by 5-HT(2A) receptor activation. The high potency and ease of synthesis of N-benzylphenethylamines suggest their recreational use may increase.
ACS Pharmacology & Translational Science
December 14, 2020
Adam K. Klein, Muhammad Chatha, Lauren J. Laskowski et al.
103 citations
The 5-HT2A receptor is the primary target for psilocybin and other serotonergic hallucinogens. Seventeen tryptamines with 4-hydroxy or 4-acetoxy groups and various N,N-dialkyl substituents were tested. All acted as full or partial agonists at 5-HT2 subtypes, with similar potencies at 5-HT2A and 5-HT2B receptors, though bulkier N-alkyl groups reduced potency at 5-HT2C receptors and increased 5-HT2B efficacy. O-acetylation reduced in vitro 5-HT2A potency by 10- to 20-fold without altering efficacy. All compounds induced head twitches in mice, consistent with LSD-like effects. Acetylation had little effect on head-twitch potency, suggesting O-acetylated tryptamines may act as prodrugs deacetylated in vivo. These derivatives have psilocybin-like properties, supporting their classification as psychedelic drugs.
Schizophrenia Bulletin
August 5, 2020
Pantelis Leptourgos, Martin Fortier-Davy, Robin Carhart‐Harris et al.
88 citations
A multidisciplinary working group reviewed evidence on the similarities and differences between hallucinations induced by psychedelics and those occurring in schizophrenia-spectrum disorders, examining data from pharmacology, brain imaging, phenomenology, and anthropology. The authors highlight both shared features and distinct characteristics across these scales, and attempt to integrate findings using computational approaches. They conclude with recommendations for future research, emphasizing the need for further study to clarify the relationship between these types of hallucinations.
Journal of Natural Products
February 20, 2020
Alexander M. Sherwood, Adam L. Halberstadt, Adam K. Klein et al.
79 citations
A new synthetic method allows access to tryptamine natural products found in psilocybin-producing mushrooms. Laboratory and animal experiments tested whether these compounds are psychoactive. In mice, the natural product baeocystin did not produce a head twitch response, a behavioral marker of psychedelic activity, even though its predicted breakdown product, norpsilocin, strongly activates the 5-HT2A receptor, which is associated with psychedelic effects. This suggests that baeocystin itself may not be psychedelic, despite its metabolite's activity.
Drug Testing and Analysis
October 12, 2015
Simon D. Brandt, Pierce V. Kavanagh, Folker Westphal et al.
79 citations
1-Propionyl-d-lysergic acid diethylamide hemitartrate (1P-LSD), a non-controlled derivative of LSD, was characterized and tested for LSD-like effects. Using chromatographic, mass spectrometric, infrared, and nuclear magnetic resonance methods, the compound was compared to LSD. In male C57BL/6J mice, 1P-LSD produced a dose-dependent increase in head-twitch response (HTR) counts, a behavioral marker of 5-HT2A receptor activation. 1P-LSD had about 38% of the potency of LSD (ED50 = 349.6 nmol/kg vs. 132.8 nmol/kg for LSD). Pretreatment with the selective 5-HT2A receptor antagonist M100907 abolished the HTR, confirming that the response was mediated by 5-HT2A receptor activation. These results indicate 1P-LSD produces LSD-like effects in mice, consistent with classification as a serotonergic hallucinogen, though human psychoactive effects remain unknown.
PLoS ONE
June 17, 2016
Jason Wallach, Heather Kang, Tristan Colestock et al.
73 citations
1,2-Diarylethylamines such as diphenidine (DPH) and 2-methoxy-diphenidine (2-MXP) are sold as 'legal highs' and have been linked to fatal and non-fatal overdoses. Binding studies at 46 central nervous system receptors show these compounds are relatively selective N-methyl-D-aspartate receptor (NMDAR) antagonists with weak off-target inhibition of dopamine and norepinephrine reuptake. In rats, DPH and 2-MXP significantly reduced prepulse inhibition of startle (PPI), an effect seen with dissociative drugs like phencyclidine (PCP) and ketamine. DPH acted with a median effective dose (ED50) of 9.5 mg/kg, less potent than PCP and ketamine.
The International Journal of Neuropsychopharmacology
August 13, 2013
Adam L. Halberstadt, Mark A. Geyer
66 citations
Serotonergic hallucinogens such as mescaline, psilocybin, and LSD produce a 'model psychosis' in healthy individuals that resembles positive symptoms of schizophrenia by acting through the serotonin 5-HT2A receptor. Evidence that the serotonergic system contributes to schizophrenia in some patients has led to animal models based on hallucinogen effects. This review examines the behavioral effects of hallucinogens in four such models, the receptor and neurochemical mechanisms involved, and their translational relevance. Despite challenges in modeling hallucinogen effects in nonverbal species, these models have provided insights into the link between serotonin and schizophrenia and identified receptor targets for developing new therapeutic agents.
ACS Chemical Neuroscience
October 28, 2019
Christian B. M. Poulie, Anders A. Jensen, Adam L. Halberstadt et al.
63 citations
N-Benzylphenethylamines (NBOMes) are synthetic psychedelics derived from phenethylamines like 2C-X compounds, which originate from the natural alkaloid mescaline. Like other classical psychedelics, they primarily activate serotonin 2A (5-HT2A) receptors. Since their emergence as New Psychoactive Substances in 2010, recreational use has caused acute toxicity and lethal outcomes, leading to their classification as Schedule I substances in 2013. Beyond recreational use, NBOMes have become valuable biochemical tools, such as [11C]Cimbi-36 for PET imaging of 5-HT2A and 5-HT2C receptors, and 25CN-NBOH, a highly selective 5-HT2A receptor agonist. This Review covers their history, chemistry, structure-activity relationships, ADME properties, and safety profiles.
Drug Testing and Analysis
June 5, 2017
Simon D. Brandt, Pierce V. Kavanagh, Brendan Twamley et al.
56 citations
Lysergic acid morpholide (LSM-775), a structural relative of LSD, appeared on the market for new psychoactive substances in 2013, but its potency and psychoactive effects in humans have been disputed. This investigation characterized a powdered sample using multiple analytical techniques and tested its receptor activity. LSM-775 acted as a nonselective agonist at 5-HT1A and 5-HT2A receptors. In head twitch studies with C57BL/6J mice, LSM-775 did not induce the head twitch response unless 5-HT1A receptors were blocked by the antagonist WAY-100,635 (1 mg/kg, subcutaneous). The findings suggest that activation of 5-HT1A receptors by LSM-775 masks its hallucinogen-like effects, consistent with reports that it produces only weak LSD-like effects in humans.
Drug Testing and Analysis
March 16, 2020
Simon D. Brandt, Pierce V. Kavanagh, Folker Westphal et al.
38 citations
1-Cylopropanoyl-LSD (1CP-LSD), a new lysergamide-based designer drug, was analyzed using multiple chemical and spectroscopic methods. Incubation with human serum converted 1CP-LSD into LSD, suggesting it may act as a prodrug for LSD in the body. In mice, 1CP-LSD induced a head-twitch response (HTR) with an ED50 of 430.0 nmol/kg, comparable to 1P-LSD (ED50 = 349.6 nmol/kg), indicating an LSD-like behavioral profile. The study includes analysis of blotters and pellets, and detected artificially induced degradation products during GC-MS analysis. Clinical studies are needed to determine its potency and effects in humans.
Neuropharmacology
November 19, 2019
Adam L. Halberstadt, Muhammad Chatha, Adam K. Klein et al.
37 citations
The ergoline d-lysergic acid diethylamide (LSD) is one of the most potent psychedelic drugs. 1-Acetyl-LSD (ALD-52) and other 1-acyl-substituted LSD derivatives, including 1-propanoyl-LSD (1P-LSD) and 1-butanoyl-LSD (1B-LSD), have appeared as designer drugs assumed to act as prodrugs for LSD. Competitive binding studies and calcium mobilization assays showed 1-acyl-substitution reduced affinity for most monoamine receptors, including 5-HT2A sites, by one to two orders of magnitude, and these derivatives had weak efficacy or acted as antagonists in Ca2+-mobilization assays. Despite this, they induced head twitches in mice with relatively high potency. High levels of LSD were detected in rat plasma after subcutaneous administration of ALD-52 and 1P-LSD, demonstrating rapid and efficient deacylation in vivo, consistent with the prediction that these compounds serve as prodrugs for LSD.
Journal of Psychopharmacology
February 21, 2019
Adam L. Halberstadt, Muhammad Chatha, Stephen J. Chapman et al.
25 citations
In mice, the hallucinogenic compound mescaline and several of its chemical analogs produce a distinctive head-twitch response that depends on activation of the 5-HT2A receptor. Adding a methyl group to mescaline (making TMA) doubled its potency, and replacing the 4-methoxy group with larger ethoxy or propoxy groups also increased potency for both mescaline and TMA. However, for a different set of isomers (TMA-2 and its analogs), changing the 4-alkoxy group did not alter potency, even though TMA-2 itself was twice as potent as mescaline. These potency patterns in mice closely match known human hallucinogenic data and show that different substitution patterns on the phenyl ring produce distinct structure-activity relationships.
Psychopharmacology
February 14, 2019
Adam L. Halberstadt, Landon M. Klein, Muhammad Chatha et al.
25 citations
The lysergamide ECPLA, a close structural analog of LSD, binds with high affinity to serotonin, adrenergic, and dopamine receptors, and acts as a potent agonist at the 5-HT₂A receptor, which mediates psychedelic effects. In mice, ECPLA induced head twitches with an ED₅₀ of 317.2 nmol/kg, about 40% as potent as LSD. Two other analogs, LAMPA (ED₅₀ = 358.3 nmol/kg) and MIPLA (ED₅₀ = 421.7 nmol/kg), showed similar or slightly lower potency. These findings indicate that ECPLA, MIPLA, and LAMPA share pharmacological properties with LSD and other lysergamide hallucinogens.
Psychopharmacology
February 14, 2019
Adam L. Halberstadt, Jochem V. F. Zee, Muhammad Chatha et al.
21 citations
Chronic treatment with an mGlu2/3 receptor agonist, LY379268, attenuated the head-twitch response (HTR) induced by the selective 5-HT2A agonist 25CN-NBOH in mice, even when tested 48 hours after the last dose. Acute LY379268 also reduced the HTR by about 50%. The HTR was completely blocked by a 5-HT2A antagonist but not by a 5-HT2C antagonist. In locomotor tests, acute LY379268 reduced PCP-induced hyperactivity in mice that had received chronic vehicle treatment, but only a trend for an interaction was seen in the chronic LY379268 group. These results support a functional interaction between mGlu2/3 and 5-HT2A receptors in modulating behavioral responses to 5-HT2A activation.
Drug Testing and Analysis
November 27, 2021
Simon D. Brandt, Pierce V. Kavanagh, Folker Westphal et al.
19 citations
A new LSD derivative called 1-valeroyl-LSD (1V-LSD, or "Valerie") has appeared on the online market. It is a higher homolog of earlier derivatives like ALD-52, 1P-LSD, and 1B-LSD. The study analytically characterized 1V-LSD using mass spectrometry, chromatography, NMR, and Raman spectroscopy. In mice, 1V-LSD induced a head-twitch response, a behavioral proxy for human hallucinogenic effects, in a dose-dependent manner. Its median effective dose was 373 nmol/kg, about a third the potency of LSD (ED50 = 132.8 nmol/kg). 1V-LSD likely acts as a prodrug that is hydrolyzed to LSD, but further studies on its biotransformation and receptor pharmacology are needed.
ACS Pharmacology & Translational Science
January 25, 2024
Thomas W. Flanagan, Timothy P. Foster, Thomas E. Galbato et al.
18 citations
Two psychedelic compounds, (R)-DOI and (R)-DOTFM, both activate the serotonin 2A receptor with comparable in vitro activity and behavioral potency, yet only (R)-DOI prevents inflammation and airway hyperresponsiveness in a mouse model of asthma. The compounds produce distinct differences in protein expression and inflammatory-related gene expression in lung tissue. The anti-inflammatory effects of certain psychedelics involve suppression of arginase 1 expression, revealing key mechanistic components of their anti-inflammatory action.
Journal of Natural Products
March 5, 2021
Janis Fricke, Alexander M. Sherwood, Adam L. Halberstadt et al.
18 citations
A novel analogue of psilocybin, 5-methylpsilocybin, was produced through a hybrid chemoenzymatic synthesis, combining chemical synthesis of 5-methylpsilocin with enzymatic phosphorylation using a purified kinase from Psilocybe cubensis. The product was isolated with high purity via solvent-antisolvent precipitation. In a mouse head-twitch response assay, 5-methylpsilocybin showed psychedelic-like activity more potent than dimethyltryptamine but less potent than psilocybin.
Drug Testing and Analysis
May 7, 2022
Simon D. Brandt, Pierce V. Kavanagh, Folker Westphal et al.
14 citations
The lysergamide 1P-AL-LAD is characterized and tested in vitro and in mice. In pooled human liver microsomes, 1P-AL-LAD converts to AL-LAD as the most abundant metabolite, supporting the idea that it acts as a prodrug. Fourteen metabolites are detected, including hydroxylation and deacylation products. In mice, 1P-AL-LAD produces a dose-dependent increase in head twitch response, a behavioral proxy for human hallucinogenic effects, with an inverted U-shaped dose-response curve. Its median effective dose is 491 nmol/kg, almost three times less potent than AL-LAD (174.9 nmol/kg). The prodrug mechanism likely explains its activity despite N1-substitution disrupting 5-HT2A receptor activation.
Psychopharmacology
December 7, 2022
Adam L. Halberstadt, Dino Luethi, Marius C. Hoener et al.
7 citations
A series of 4-thio-substituted phenylalkylamines, including the psychedelic drugs 2C-T-2 and 2C-T-7, were tested in mice using the head twitch response (HTR), a behavioral proxy for human psychedelic effects. Adding an α-methyl group to the parent compound 2C-T increased potency fivefold, and extending the 4-methylthio group by one to three methylene units also increased potency. Fluorination of the 4-position alkylthio chain or a 4-allylthio substituent reduced activity, and bulky 4-benzylthio groups showed little or no effect. Binding studies confirmed nanomolar affinity for 5-HT2 receptor subtypes and partial agonism at 5-HT2A, supporting classification of these compounds as psychedelic drugs.
Drug Testing and Analysis
August 24, 2020
Simon D. Brandt, Pierce V. Kavanagh, Folker Westphal et al.
5 citations
N-ethyl-N-cyclopropyl lysergamide (ECPLA) produces LSD-like behavioral effects in mice and may act as a hallucinogen in humans. ECPLA is an isomer of the recreational drug LSZ. Several analytical methods—mass spectrometry, gas and liquid chromatography, nuclear magnetic resonance spectroscopy, and GC condensed-phase infrared spectroscopy—can differentiate ECPLA from LSZ. Key mass spectral differences include ion abundances at m/z 196, 207/208, 98, and 41. Electrospray ionization spectra show lysergamide-related ions, and LSZ (but not ECPLA) produces product ions at m/z 267 and 98 under the conditions used. These data support forensic and clinical detection of ECPLA.
UNC Libraries
October 29, 2020
Simon D. Brandt, Maria F. Sassano, David E. Nichols et al.
4 citations
A series of N-benzylated-5-methoxytryptamine analogues and N-benzylated analogues of 2,5-dimethoxy-4-iodophenethylamine (2C-I) were synthesized and tested. Most compounds showed highest affinity for the 5-HT2 family of serotonin receptors. Substitution at the para position of the benzyl group reduced affinity, while ortho or meta substitution enhanced it. Large lipophilic groups improved affinity but often reduced functional activity. Functional potency was measured at human 5-HT2A, 5-HT2B, and 5-HT2C receptors and rat 5-HT2A and 5-HT2C receptors using intracellular calcium mobilization. Several tryptamine congeners were very potent functionally (EC50 values from 7.6 to 63 nM) but were mostly partial agonists. In mouse head twitch tests, many compounds induced the behavior, which correlated significantly with functional potency at the rat 5-HT2A receptor.
Schizophrenia Bulletin
April 17, 2025
Nathan H. Heller, Frederick S. Barrett, Tobias Buchborn et al.
3 citations
Visual hallucinations in Lewy body diseases (Parkinson's disease and dementia with Lewy bodies) and those induced by serotonergic psychedelics (psilocybin, mescaline) share overlapping phenomenology and neural mechanisms, despite different underlying causes. Both conditions produce visual aberrations from minor distortions to complex hallucinations, including illusory motion and entity encounters. Neuroimaging shows a common pattern of overactive associative cortex and underactive sensory cortex. Serotonin 2A receptor modulation is involved in both: psychedelics act through 5-HT2A and 5-HT1A receptors, while in Lewy body diseases, 5-HT2A receptor upregulation correlates with increased hallucinations, and blocking it with pimavanserin reduces them. Shared cortical signatures include reduced visual evoked responses and shifts toward visual excitation.