Psychopharmacology
December 9, 2010
Adam L. Halberstadt, Virginia Lehmann-Masten, Mark A. Geyer et al.
35 citations
Loss of metabotropic glutamate 5 (mGlu5) receptor activity, either through gene deletion or pharmacological blockade, causes locomotor hyperactivity and reduced habituation in mice. The serotonergic hallucinogen and 5-HT2A agonist DOM (0.5 mg/kg) increased this hyperactivity, while the 5-HT2A antagonist M100907 (1.0 mg/kg) reduced it. M100907 (0.1 mg/kg) also blocked hyperactivity induced by the mGlu5-negative allosteric modulator MPEP. These findings indicate a functional interaction between mGlu5 and 5-HT2A receptors, suggesting mGlu5 receptors may mitigate the behavioral effects of 5-HT2A hallucinogens or that mGlu5 knockout mice have increased sensitivity to such agonists.
Pharmacology, biochemistry, and behavior
April 1, 2016
Adam L. Halberstadt
33 citations
Combining 5-MeO-DMT with monoamine oxidase inhibitors (MAOIs) changes how the drug affects behavior in rats. 5-MeO-DMT alone did not disrupt prepulse inhibition (PPI), a measure of sensorimotor gating, but when rats were pretreated with the MAO-A inhibitor clorgyline or the MAO-A/B inhibitor pargyline, the drug disrupted PPI. This disruption was blocked by antagonists of either 5-HT1A or 5-HT2A receptors, indicating both receptor types are involved. MAO-A inhibition increased levels of 5-MeO-DMT in plasma and whole brain but did not affect its conversion to bufotenine, which was negligible. The findings suggest that MAOIs enhance the drug's effects by increasing its accumulation in the central nervous system.
Behavioural Brain Research
October 1, 2020
Dionisio A Amodeo, Omron Hassan, Landon M. Klein et al.
25 citations
Activating serotonin 2A (5-HT2A) receptors impairs behavioral flexibility in male mice, as measured by a probabilistic reversal learning task. The selective 5-HT2A agonist 25CN-NBOH increased the number of trials needed to reach criterion during reversal learning, while the broader agonist DOI alone did not. However, combining DOI with a 5-HT2C receptor antagonist (SER-082) also impaired reversal learning, suggesting that 5-HT2A and 5-HT2C receptors have opposing effects on this aspect of executive function. All groups performed similarly on the initial spatial discrimination, indicating that the impairment was specific to adapting to changing contingencies.
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.
Neuropharmacology
January 1, 2019
Adam L. Halberstadt, Muhammad Chatha, Alexander Stratford et al.
25 citations
Rigid analogs of phenylalkylamine hallucinogens, such as 2C-B-FLY and Bromo-DragonFLY (DOB-DFLY), have emerged as recreational drugs. In mice, the head twitch response—a behavior mediated by the 5-HT2A receptor—was used to compare potencies. DOB (ED50 = 0.75 μmol/kg) and 2C-B (ED50 = 2.43 μmol/kg) induced the response. Benzodifurans DOB-DFLY (ED50 = 0.20 μmol/kg) and 2C-B-DFLY (ED50 = 1.07 μmol/kg) showed significantly higher potency than their non-rigid counterparts. Tetrahydrobenzodifurans DOB-FLY (ED50 = 0.67 μmol/kg) and 2C-B-FLY (ED50 = 1.79 μmol/kg) were approximately equipotent. Three novel tetrahydrobenzodifurans were active but had relatively low potency.
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.
ACS Chemical Neuroscience
May 6, 2020
Emil Märcher-Rørsted, Adam L. Halberstadt, Adam K. Klein et al.
20 citations
The 2,5-dimethoxy motif found in many phenethylamine psychedelics has been considered essential for activating the serotonin 2A receptor (5-HT2AR). This study synthesized derivatives of 2C-B and DOB lacking either the 2- or 5-methoxy group and tested them in binding and functional assays at 5-HT2AR and 5-HT2CR, as well as in mice for head-twitch response, a behavioral proxy for psychedelic activity. Removing either methoxy group caused a modest drop in binding affinity and functional potency at both receptors, with larger effects from removing the 2-methoxy group. However, in mice, removal of either group drastically reduced head-twitch response. Thus, the 2,5-dimethoxy motif is important for in vivo potency, but this does not correlate with in vitro receptor affinity or potency.
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.
Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology
March 1, 2022
Deborah Rudin, John D. Mccorvy, Grant C. Glatfelter et al.
18 citations
Derivatives of (2-aminopropyl)indole and (2-aminopropyl)benzofuran are new psychoactive substances with stimulant effects. This study characterized six isomers of the sulfur-based analog (2-aminopropyl)benzo[β]thiophene (APBT) in vitro and three isomers in vivo. APBTs inhibited monoamine reuptake and induced transporter-mediated substrate release, similar to MDMA, but did not stimulate locomotion in mice. Instead, they acted as full agonists at 5-HT2 receptor subtypes and induced head-twitch responses, indicating psychedelic-like activity. Replacing oxygen with sulfur enhanced serotonin transporter release potency and 5-HT2 receptor activity, shifting the profile toward psychedelic and entactogenic effects with minimal psychomotor stimulation, suggesting potential for drug-assisted psychotherapy.
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
January 1, 2017
Simon D. Brandt, Pierce V. Kavanagh, Geraldine Dowling et al.
16 citations
Many N,N-dialkylated tryptamines have psychoactive properties in humans, and the number of derivatives has grown across research areas. Some are used in medicinal products, others as recreational drugs, and sometimes these uses overlap. 5-Methoxy-N,N-diallyltryptamine (5-MeO-DALT) recently emerged as a new psychoactive substance, while 4-acetoxy-DALT and unsubstituted DALT have been detected only recently. This report describes the analytical characterization of 17 N,N-diallyltryptamines (DALTs), including 15 prepared via microwave-accelerated synthesis. The compounds were characterized using NMR, GC-MS, mass spectrometry, photodiode array detection, and GC solid-state infrared analysis. The resulting spectral data are provided to help researchers identify newly emerging substances and explore clinical and non-clinical uses.
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.
bioRxiv (Cold Spring Harbor Laboratory)
July 31, 2023
Jason Wallach, Andrew B. Cao, Maggie M. Calkins et al.
11 citations
preprint
Serotonergic psychedelics show therapeutic promise, but the specific signaling pathways responsible for their effects have been unclear. Researchers developed a series of 5-HT2A receptor ligands with varying Gq efficacies, including β-arrestin-biased ligands. They found that 5-HT2A-Gq efficacy, not β-arrestin2 efficacy, predicts psychedelic potential, measured by head-twitch response in male mice. Disrupting Gq-PLC signaling reduced this response, and a threshold of Gq activation is needed for psychedelic-like effects, explaining why some partial agonists like lisuride are non-psychedelic. β-arrestin-biased agonists caused receptor downregulation and tachyphylaxis, and showed an anti-psychotic-like profile. This fine-tuning of 5-HT2A signaling can generate ligands distinct from classical psychedelics.
Frontiers in Pharmacology
January 1, 2013
Wendy K. Adams, Adam L. Halberstadt, Maarten Van den Buuse
11 citations
Blocking NMDA receptors with phencyclidine (PCP) can produce schizophrenia-like symptoms in humans, but PCP also affects other systems. Rats with serotonin-depleting lesions in the dorsal hippocampus showed increased hyperactivity from PCP but not from the more selective NMDA blocker MK-801. Lesions in the ventral hippocampus had no effect. PCP and MK-801 both made the rats' movement paths smoother and less predictable, but the dorsal hippocampus lesions did not alter these qualitative effects for PCP, though they slightly reduced MK-801's effect on unpredictability. The results reveal a functional difference between PCP and MK-801 related to serotonin in the dorsal hippocampus, relevant to schizophrenia research.
Drug Testing and Analysis
January 1, 2025
Pierce V. Kavanagh, Folker Westphal, Benedikt Pulver et al.
8 citations
A novel LSD derivative, 1-dodecanoyl-LSD (1DD-LSD), was synthesized and tested in mice to see if it produces LSD-like effects. The compound induced a head-twitch response in C57BL/6J mice with a median effective dose of 2.17 mg/kg (3.60 μmol/kg). LSD was 27-fold more potent than 1DD-LSD under similar conditions. Other homologues, such as ALD-52 and 1-propanoyl-LSD, also showed considerably higher potency, suggesting that hydrolysis of the 1-dodecanoyl moiety may be less efficient in vivo. The increased lipophilicity of 1DD-LSD might cause it to be sequestered in fat, reducing enzymatic hydrolysis. Further studies are needed to assess its activity in humans and its potential as a long-acting prodrug for LSD.
Drug Testing and Analysis
March 1, 2023
Pierce V. Kavanagh, Folker Westphal, Benedikt Pulver et al.
7 citations
A new lysergamide, 1cP-AL-LAD, was analyzed using chromatographic, mass spectrometric, and spectroscopic methods. A powdered sample from an online vendor contained 17 impurities, including AL-LAD and 1P-AL-LAD (confirmed by reference standards) and tentatively identified compounds such as 1-acetyl-AL-LAD and oxidation products of the N6-allyl group and ergoline ring. The substance was also found in blotter paper samples sold online for recreational use. These findings provide analytical data for researchers interested in lysergamide chemistry.
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
December 3, 2024
Simon D. Brandt, Pierce V. Kavanagh, Sarah Gare et al.
5 citations
1-(2-furoyl)-lysergic acid diethylamide (1F-LSD, SYN-L-005) is a novel analog of the recently detected recreational drug 1-(thiophene-2-carbonyl)-LSD (1T-LSD). Both substances are N1-acylated LSD derivatives that bind to the 5-HT2A receptor, the primary site of action for psychedelic drugs. In C57BL/6J mice, 1F-LSD and 1T-LSD induced the head-twitch response, a 5-HT2A-mediated behavior, and were hydrolyzed to LSD after administration. These findings indicate that both compounds exhibit LSD-like properties and likely act as prodrugs for LSD, releasing the active drug in the body.
Drug Testing and Analysis
February 1, 2024
Simon D. Brandt, Pierce V. Kavanagh, Folker Westphal et al.
5 citations
N-ethyl-N-isopropyllysergamide (EIPLA), an isomer of the psychedelic lysergamide ETH-LAD, shows LSD-like properties in preclinical tests. Mass spectrometry, chromatography, and NMR spectroscopy distinguished EIPLA from ETH-LAD by their structural features. Blotter extracts contained 96.9 ± 0.5 μg and 85.8 ± 2.8 μg of EIPLA base. In mice, EIPLA induced head-twitch responses (ED50 = 234.6 nmol/kg), about half the potency of LSD (ED50 = 132.8 nmol/kg), consistent with serotonergic psychedelic effects. Analytical data are provided to aid forensic and clinical identification.
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.
Drug Testing and Analysis
April 1, 2025
Simon D. Brandt, Pierce V. Kavanagh, Sarah Gare et al.
4 citations
A newly developed LSD derivative, 1-hexanoyl-LSD (1H-LSD), was characterized analytically and tested in mice using the head-twitch response assay, a behavioral proxy for psychedelic activity. 1H-LSD induced head-twitch responses with a median effective dose of 192.4 μg/kg, making it roughly as potent as the known analog 1A-LSD (ALD-52) under similar conditions. Like other N1-acylated LSD derivatives, 1H-LSD is expected to be hydrolyzed to LSD in the body, acting as a prodrug. It is not yet known whether this compound has appeared on the recreational drug market or in research chemical supplies.
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.