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Straumann I, Ley L, Holze F, Becker AM, Klaiber A, Wey K, Duthaler U, Varghese N, Eckert A, Liechti ME. Acute effects of MDMA and LSD co-administration in a double-blind placebo-controlled study in healthy participants. Neuropsychopharmacology 2023; 48:1840-1848. [PMID: 37258715 PMCID: PMC10584820 DOI: 10.1038/s41386-023-01609-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 04/17/2023] [Accepted: 05/12/2023] [Indexed: 06/02/2023]
Abstract
There is renewed interest in the use of lysergic acid diethylamide (LSD) in psychiatric research and practice. Although acute subjective effects of LSD are mostly positive, negative subjective effects, including anxiety, may occur. The induction of overall positive acute subjective effects is desired in psychedelic-assisted therapy because positive acute experiences are associated with greater therapeutic long-term benefits. 3,4-Methylenedioxymethamphetamine (MDMA) produces marked positive subjective effects and is used recreationally with LSD, known as "candyflipping." The present study investigated whether the co-administration of MDMA can be used to augment acute subjective effects of LSD. We used a double-blind, randomized, placebo-controlled, crossover design with 24 healthy subjects (12 women, 12 men) to compare the co-administration of MDMA (100 mg) and LSD (100 µg) with MDMA and LSD administration alone and placebo. Outcome measures included subjective, autonomic, and endocrine effects and pharmacokinetics. MDMA co-administration with LSD did not change the quality of acute subjective effects compared with LSD alone. However, acute subjective effects lasted longer after LSD + MDMA co-administration compared with LSD and MDMA alone, consistent with higher plasma concentrations of LSD (Cmax and area under the curve) and a longer plasma elimination half-life of LSD when MDMA was co-administered. The LSD + MDMA combination increased blood pressure, heart rate, and pupil size more than LSD alone. Both MDMA alone and the LSD + MDMA combination increased oxytocin levels more than LSD alone. Overall, the co-administration of MDMA (100 mg) did not improve acute effects or the safety profile of LSD (100 µg). The combined use of MDMA and LSD is unlikely to provide relevant benefits over LSD alone in psychedelic-assisted therapy. Trial registration: ClinicalTrials.gov identifier: NCT04516902.
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Affiliation(s)
- Isabelle Straumann
- Clinical Pharmacology and Toxicology, Department of Biomedicine and Department of Clinical Research, University Hospital Basel, Basel, Switzerland
- Department of Pharmaceutical Sciences, University of Basel, Basel, Switzerland
| | - Laura Ley
- Clinical Pharmacology and Toxicology, Department of Biomedicine and Department of Clinical Research, University Hospital Basel, Basel, Switzerland
- Department of Pharmaceutical Sciences, University of Basel, Basel, Switzerland
| | - Friederike Holze
- Clinical Pharmacology and Toxicology, Department of Biomedicine and Department of Clinical Research, University Hospital Basel, Basel, Switzerland
- Department of Pharmaceutical Sciences, University of Basel, Basel, Switzerland
| | - Anna M Becker
- Clinical Pharmacology and Toxicology, Department of Biomedicine and Department of Clinical Research, University Hospital Basel, Basel, Switzerland
- Department of Pharmaceutical Sciences, University of Basel, Basel, Switzerland
| | - Aaron Klaiber
- Clinical Pharmacology and Toxicology, Department of Biomedicine and Department of Clinical Research, University Hospital Basel, Basel, Switzerland
- Department of Pharmaceutical Sciences, University of Basel, Basel, Switzerland
| | - Kathrin Wey
- Clinical Pharmacology and Toxicology, Department of Biomedicine and Department of Clinical Research, University Hospital Basel, Basel, Switzerland
- Department of Pharmaceutical Sciences, University of Basel, Basel, Switzerland
| | - Urs Duthaler
- Clinical Pharmacology and Toxicology, Department of Biomedicine and Department of Clinical Research, University Hospital Basel, Basel, Switzerland
- Department of Pharmaceutical Sciences, University of Basel, Basel, Switzerland
| | - Nimmy Varghese
- Psychiatric University Hospital, University of Basel, Basel, Switzerland
- Transfaculty Research Platform Molecular and Cognitive Neuroscience, University of Basel, Basel, Switzerland
| | - Anne Eckert
- Psychiatric University Hospital, University of Basel, Basel, Switzerland
- Transfaculty Research Platform Molecular and Cognitive Neuroscience, University of Basel, Basel, Switzerland
| | - Matthias E Liechti
- Clinical Pharmacology and Toxicology, Department of Biomedicine and Department of Clinical Research, University Hospital Basel, Basel, Switzerland.
- Department of Pharmaceutical Sciences, University of Basel, Basel, Switzerland.
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Banushi B, Polito V. A Comprehensive Review of the Current Status of the Cellular Neurobiology of Psychedelics. BIOLOGY 2023; 12:1380. [PMID: 37997979 PMCID: PMC10669348 DOI: 10.3390/biology12111380] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 10/26/2023] [Accepted: 10/26/2023] [Indexed: 11/25/2023]
Abstract
Psychedelic substances have gained significant attention in recent years for their potential therapeutic effects on various psychiatric disorders. This review delves into the intricate cellular neurobiology of psychedelics, emphasizing their potential therapeutic applications in addressing the global burden of mental illness. It focuses on contemporary research into the pharmacological and molecular mechanisms underlying these substances, particularly the role of 5-HT2A receptor signaling and the promotion of plasticity through the TrkB-BDNF pathway. The review also discusses how psychedelics affect various receptors and pathways and explores their potential as anti-inflammatory agents. Overall, this research represents a significant development in biomedical sciences with the potential to transform mental health treatments.
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Affiliation(s)
- Blerida Banushi
- Genetics and Genomic Medicine Department, Great Ormond Street Institute of Child Health, University College London, London WC1N 1EH, UK
| | - Vince Polito
- School of Psychological Sciences, Macquarie University, Sydney, NSW 2109, Australia;
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Kanen JW, Luo Q, Rostami Kandroodi M, Cardinal RN, Robbins TW, Nutt DJ, Carhart-Harris RL, den Ouden HEM. Effect of lysergic acid diethylamide (LSD) on reinforcement learning in humans. Psychol Med 2022; 53:1-12. [PMID: 36411719 PMCID: PMC10600934 DOI: 10.1017/s0033291722002963] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 08/28/2022] [Accepted: 08/31/2022] [Indexed: 11/23/2022]
Abstract
BACKGROUND The non-selective serotonin 2A (5-HT2A) receptor agonist lysergic acid diethylamide (LSD) holds promise as a treatment for some psychiatric disorders. Psychedelic drugs such as LSD have been suggested to have therapeutic actions through their effects on learning. The behavioural effects of LSD in humans, however, remain incompletely understood. Here we examined how LSD affects probabilistic reversal learning (PRL) in healthy humans. METHODS Healthy volunteers received intravenous LSD (75 μg in 10 mL saline) or placebo (10 mL saline) in a within-subjects design and completed a PRL task. Participants had to learn through trial and error which of three stimuli was rewarded most of the time, and these contingencies switched in a reversal phase. Computational models of reinforcement learning (RL) were fitted to the behavioural data to assess how LSD affected the updating ('learning rates') and deployment of value representations ('reinforcement sensitivity') during choice, as well as 'stimulus stickiness' (choice repetition irrespective of reinforcement history). RESULTS Raw data measures assessing sensitivity to immediate feedback ('win-stay' and 'lose-shift' probabilities) were unaffected, whereas LSD increased the impact of the strength of initial learning on perseveration. Computational modelling revealed that the most pronounced effect of LSD was the enhancement of the reward learning rate. The punishment learning rate was also elevated. Stimulus stickiness was decreased by LSD, reflecting heightened exploration. Reinforcement sensitivity differed by phase. CONCLUSIONS Increased RL rates suggest LSD induced a state of heightened plasticity. These results indicate a potential mechanism through which revision of maladaptive associations could occur in the clinical application of LSD.
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Affiliation(s)
- Jonathan W. Kanen
- Department of Psychology, University of Cambridge, Cambridge, UK
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK
| | - Qiang Luo
- National Clinical Research Center for Aging and Medicine at Huashan Hospital, State Key Laboratory of Medical Neurobiology and Ministry of Education Frontiers Center for Brain Science, Institutes of Brain Science and Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, 200433, China
- Center for Computational Psychiatry, Ministry of Education-Key Laboratory of Computational Neuroscience and Brain-Inspired Intelligence, Human Phenome Institute, Fudan University, Shanghai, 200032, China
- Shanghai Key Laboratory of Mental Health and Psychological Crisis Intervention, School of Psychology and Cognitive Science, East China Normal University, Shanghai, 200241, China
| | - Mojtaba Rostami Kandroodi
- Department of Cognitive Science and Artificial Intelligence, Tilburg University, Tilburg, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
| | - Rudolf N. Cardinal
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK
- Department of Psychiatry, University of Cambridge, Cambridge, UK
- Cambridgeshire and Peterborough NHS Foundation Trust, Cambridge, UK
| | - Trevor W. Robbins
- Department of Psychology, University of Cambridge, Cambridge, UK
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK
| | - David J. Nutt
- Department of Brain Sciences, Centre for Psychedelic Research, Imperial College London, London, UK
| | - Robin L. Carhart-Harris
- Neuroscape Psychedelics Division, University of California San Francisco, San Francisco, California, USA
| | - Hanneke E. M. den Ouden
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
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Dourron HM, Strauss C, Hendricks PS. Self-Entropic Broadening Theory: Toward a New Understanding of Self and Behavior Change Informed by Psychedelics and Psychosis. Pharmacol Rev 2022; 74:982-1027. [DOI: 10.1124/pharmrev.121.000514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 06/14/2022] [Accepted: 06/16/2022] [Indexed: 11/22/2022] Open
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van Elk M, Yaden DB. Pharmacological, neural, and psychological mechanisms underlying psychedelics: A critical review. Neurosci Biobehav Rev 2022; 140:104793. [PMID: 35878791 DOI: 10.1016/j.neubiorev.2022.104793] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Revised: 07/08/2022] [Accepted: 07/20/2022] [Indexed: 10/17/2022]
Abstract
This paper provides a critical review of several possible mechanisms at different levels of analysis underlying the effects and therapeutic potential of psychedelics. At the (1) biochemical level, psychedelics primarily affect the 5-HT2A receptor, increase neuroplasticity, offer a critical period for social reward learning, and have anti-inflammatory properties. At the (2) neural level, psychedelics have been associated with reduced efficacy of thalamo-cortical filtering, the loosening of top-down predictive signaling and an increased sensitivity to bottom-up prediction errors, and activation of the claustro-cortical-circuit. At the (3) psychological level, psychedelics have been shown to induce altered and affective states, they affect cognition, induce belief change, exert social effects, and can result in lasting changes in behavior. We outline the potential for a unifying account of the mechanisms underlying psychedelics and contrast this with a model of pluralistic causation. Ultimately, a better understanding of the specific mechanisms underlying the effects of psychedelics could allow for a more targeted therapeutic approach. We highlight current challenges for psychedelic research and provide a research agenda to foster insight in the causal-mechanistic pathways underlying the efficacy of psychedelic research and therapy.
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Affiliation(s)
- Michiel van Elk
- Institute of Psychology, Leiden University, Wassenaarseweg 52, 2333 AK Leiden, the Netherlands.
| | - David Bryce Yaden
- The Center for Psychedelic and Consciousness Research, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, USA
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Lawn T, Dipasquale O, Vamvakas A, Tsougos I, Mehta MA, Howard MA. Differential contributions of serotonergic and dopaminergic functional connectivity to the phenomenology of LSD. Psychopharmacology (Berl) 2022; 239:1797-1808. [PMID: 35322297 PMCID: PMC9166846 DOI: 10.1007/s00213-022-06117-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 03/11/2022] [Indexed: 02/25/2023]
Abstract
RATIONALE LSD is the prototypical psychedelic. Despite a clear central role of the 5HT2a receptor in its mechanism of action, the contributions of additional receptors for which it shows affinity and agonist activity remain unclear. OBJECTIVES We employed receptor-enriched analysis of functional connectivity by targets (REACT) to explore differences in functional connectivity (FC) associated with the distributions of the primary targets of LSD-the 5HT1a, 5HT1b, 5HT2a, D1 and D2 receptors. METHODS We performed secondary analyses of an openly available dataset (N = 15) to estimate the LSD-induced alterations in receptor-enriched FC maps associated with these systems. Principal component analysis (PCA) was employed as a dimension reduction strategy for subjective experiences associated with LSD captured by the Altered States of Consciousness (ASC) questionnaire. Correlations between these principal components as well as VAS ratings of subjective effects with receptor-enriched FC were explored. RESULTS Compared to placebo, LSD produced differences in FC when the analysis was enriched with each of the primary serotonergic and dopaminergic receptors. Altered receptor-enriched FC showed relationships with the subjective effects of LSD on conscious experience, with serotonergic and dopaminergic systems being predominantly associated with perceptual effects and perceived selfhood as well as cognition respectively. These relationships were dissociable, with different receptors showing the same relationships within, but not between, the serotonergic and dopaminergic systems. CONCLUSIONS These exploratory findings provide new insights into the pharmacology of LSD and highlight the need for additional investigation of non-5HT2a-mediated mechanisms.
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Affiliation(s)
- Timothy Lawn
- Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, UK
| | - Ottavia Dipasquale
- Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, UK
| | - Alexandros Vamvakas
- Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, UK
- Medical Physics Department, School of Medicine, University of Thessaly, Larissa, Greece
| | - Ioannis Tsougos
- Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, UK
- Medical Physics Department, School of Medicine, University of Thessaly, Larissa, Greece
| | - Mitul A. Mehta
- Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, UK
| | - Matthew A. Howard
- Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, UK
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7
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Tagliazucchi E. Language as a Window Into the Altered State of Consciousness Elicited by Psychedelic Drugs. Front Pharmacol 2022; 13:812227. [PMID: 35392561 PMCID: PMC8980225 DOI: 10.3389/fphar.2022.812227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 03/01/2022] [Indexed: 11/22/2022] Open
Abstract
Psychedelics are drugs capable of eliciting profound alterations in the subjective experience of the users, sometimes with long-lasting consequences. Because of this, psychedelic research tends to focus on human subjects, given their capacity to construct detailed narratives about the contents of their consciousness experiences. In spite of its relevance, the interaction between serotonergic psychedelics and language production is comparatively understudied in the recent literature. This review is focused on two aspects of this interaction: how the acute effects of psychedelic drugs impact on speech organization regardless of its semantic content, and how to characterize the subjective effects of psychedelic drugs by analyzing the semantic content of written retrospective reports. We show that the computational characterization of language production is capable of partially predicting the therapeutic outcome of individual experiences, relate the effects elicited by psychedelics with those associated with other altered states of consciousness, draw comparisons between the psychedelic state and the symptomatology of certain psychiatric disorders, and investigate the neurochemical profile and mechanism of action of different psychedelic drugs. We conclude that researchers studying psychedelics can considerably expand the range of their potential scientific conclusions by analyzing brief interviews obtained before, during and after the acute effects. Finally, we list a series of questions and open problems that should be addressed to further consolidate this approach.
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Affiliation(s)
- Enzo Tagliazucchi
- Latin American Brain Health Institute (BrainLat), Universidad Adolfo Ibanez, Santiago, Chile.,Departamento de Física, Universidad de Buenos Aires and Instituto de Física de Buenos Aires (IFIBA, CONICET), Pabellón I, Ciudad Universitaria (1428), Buenos Aires, Argentina
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8
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van den Berg M, Magaraggia I, Schreiber R, Hillhouse TM, Porter JH. How to account for hallucinations in the interpretation of the antidepressant effects of psychedelics: a translational framework. Psychopharmacology (Berl) 2022; 239:1853-1879. [PMID: 35348806 PMCID: PMC9166823 DOI: 10.1007/s00213-022-06106-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 02/24/2022] [Indexed: 01/02/2023]
Abstract
RATIONALE Recent trials with psychedelics in major depressive disorder and treatment-resistant depression showed remarkable improvements in depressive symptoms that can last for up to several months after even a single administration. The lack of an appropriate placebo control group-as patients are often able to discriminate the subjective effects of the drug-and an incomplete understanding of the role of the hallucinogenic and mystical experience, hampers the interpretation of these therapeutic effects. OBJECTIVES To control for these factors, we developed a translational framework based on establishing pharmacokinetic/pharmacodynamic (PK/PD) relationships in rodents and humans for hallucinogenic (i.e., discriminative stimulus effects in rodents and humans; head twitch responses in rodents; questionnaires in humans) and therapeutic effects. For the latter, we selected the pattern separation and attentional set-shifting tasks as measures for cognitive flexibility because of their high translational value. We predict that these PK/PD analyses will lead to a more objective evaluation of improvements in patients compared to relying only on the currently used self-reported questionnaires. We hypothesize that-if the role of the hallucinogenic experience is not central in the antidepressant effects of psychedelics-the ED50's for the therapeutic effects will be significantly lower than for the hallucinogenic and mystical effects. CONCLUSION Our framework will help to inform future studies that aim at the elucidation of the mechanism(s) of action of psychedelics in depression, and the role of the acute subjective and/or hallucinogenic experience in their effects.
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Affiliation(s)
- Manon van den Berg
- Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, The Netherlands ,Faculty of Psychology and Neuroscience, Section Neuropsychology & Psychopharmacology, Maastricht University, Maastricht, The Netherlands
| | - Igor Magaraggia
- Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, The Netherlands ,Faculty of Psychology and Neuroscience, Section Neuropsychology & Psychopharmacology, Maastricht University, Maastricht, The Netherlands
| | - Rudy Schreiber
- Faculty of Psychology and Neuroscience, Section Neuropsychology & Psychopharmacology, Maastricht University, Maastricht, The Netherlands.
| | - Todd M. Hillhouse
- Department of Psychology, University of Wisconsin Green Bay, Green Bay, WI USA
| | - Joseph H. Porter
- Department of Psychology, Virginia Commonwealth University, Richmond, USA
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Jaster AM, de la Fuente Revenga M, González-Maeso J. Molecular targets of psychedelic-induced plasticity. J Neurochem 2021; 162:80-88. [PMID: 34741320 DOI: 10.1111/jnc.15536] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 11/02/2021] [Accepted: 11/02/2021] [Indexed: 12/15/2022]
Abstract
Psychedelic research across different disciplines and biological levels is growing at a remarkably fast pace. In the prospect of a psychedelic drug becoming again an approved treatment, much of these efforts have been oriented toward exploring the relationship between the actual psychedelic effects and those manifestations of therapeutic interest. Considering the central role of the serotonin 5-HT2A receptor in the distinct effects of psychedelics in human psyche, neuropharmacology sits at the center of this debate and exploratory continuum. Here we discuss some of the most recent findings in human studies and contextualize them considering previous preclinical models studying phenomena related to synaptic plasticity. A special emphasis is placed on knowledge gaps, challenges, and limitations to evaluate the underpinnings of psychedelics' potential antidepressant action.
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Affiliation(s)
- Alaina M Jaster
- Department of Physiology & Biophysics, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA.,Department of Pharmacology & Toxicology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Mario de la Fuente Revenga
- Department of Physiology & Biophysics, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA.,Virginia Institute of Psychiatric and Behavioral Genetics, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Javier González-Maeso
- Department of Physiology & Biophysics, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
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10
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Vejmola Č, Tylš F, Piorecká V, Koudelka V, Kadeřábek L, Novák T, Páleníček T. Psilocin, LSD, mescaline, and DOB all induce broadband desynchronization of EEG and disconnection in rats with robust translational validity. Transl Psychiatry 2021; 11:506. [PMID: 34601495 PMCID: PMC8487430 DOI: 10.1038/s41398-021-01603-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 07/16/2021] [Accepted: 08/18/2021] [Indexed: 12/22/2022] Open
Abstract
Serotonergic psychedelics are recently gaining a lot of attention as a potential treatment of several neuropsychiatric disorders. Broadband desynchronization of EEG activity and disconnection in humans have been repeatedly shown; however, translational data from animals are completely lacking. Therefore, the main aim of our study was to assess the effects of tryptamine and phenethylamine psychedelics (psilocin 4 mg/kg, LSD 0.2 mg/kg, mescaline 100 mg/kg, and DOB 5 mg/kg) on EEG in freely moving rats. A system consisting of 14 cortical EEG electrodes, co-registration of behavioral activity of animals with subsequent analysis only in segments corresponding to behavioral inactivity (resting-state-like EEG) was used in order to reach a high level of translational validity. Analyses of the mean power, topographic brain-mapping, and functional connectivity revealed that all of the psychedelics irrespective of the structural family induced overall and time-dependent global decrease/desynchronization of EEG activity and disconnection within 1-40 Hz. Major changes in activity were localized on the large areas of the frontal and sensorimotor cortex showing some subtle spatial patterns characterizing each substance. A rebound of occipital theta (4-8 Hz) activity was detected at later stages after treatment with mescaline and LSD. Connectivity analyses showed an overall decrease in global connectivity for both the components of cross-spectral and phase-lagged coherence. Since our results show almost identical effects to those known from human EEG/MEG studies, we conclude that our method has robust translational validity.
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Affiliation(s)
- Čestmír Vejmola
- National Institute of Mental Health, Klecany, Czechia
- Third Faculty of Medicine, Charles University, Prague, Czechia
| | - Filip Tylš
- National Institute of Mental Health, Klecany, Czechia
- Third Faculty of Medicine, Charles University, Prague, Czechia
| | - Václava Piorecká
- National Institute of Mental Health, Klecany, Czechia
- Department of Biomedical Technology, Faculty of Biomedical Engineering, Czech Technical University in Prague, Prague, Czechia
| | | | | | - Tomáš Novák
- National Institute of Mental Health, Klecany, Czechia
| | - Tomáš Páleníček
- National Institute of Mental Health, Klecany, Czechia.
- Third Faculty of Medicine, Charles University, Prague, Czechia.
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11
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Re-evaluation of the discriminative stimulus effects of lysergic acid diethylamide with male and female Sprague-Dawley rats. Behav Pharmacol 2021; 31:776-786. [PMID: 32960851 DOI: 10.1097/fbp.0000000000000589] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Recent discoveries from clinical trials with psychedelic-assisted therapy have led to a resurgence of interest in the psychopharmacology of lysergic acid diethylamide (LSD). Preclinical drug discrimination is an invaluable tool to investigate the neurochemical mechanisms underlying subjective drug effects. The current study extends previous drug discrimination research by including both sexes. Adult female (n = 8) and male (n = 8) Sprague-Dawley rats were trained to discriminate 0.08 mg/kg LSD from saline under a fixed ratio 20 schedule of food reinforcement. Substitution tests were conducted with several substances, including other serotonergic hallucinogens, psychostimulants, mixed psychedelic-stimulants and synthetic cathinones. Stimulus antagonist tests were conducted with selected serotonin and dopamine antagonists. LSD-substitution with serotonergic hallucinogens was comparable between sexes. Modest but intriguing differences were observed between male and female rats in the extent of partial substitution by 3,4-methylenedioxymethamphetamine and 3,4-methylenedioxyamphetamine enantiomers and the synthetic cathinones, 3,4-methylenedioxypyrovalerone and 4-methylmethcathinone. Dopamine antagonists failed to block the LSD cue in both sexes and exerted stronger rate suppressant effects in male rats. The 5-hydroxytryptamine antagonist, (R)-(+)-a-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenyl) ethyl]-4-piperidinemethanol (MDL 100 907) blocked LSD discrimination in both sexes, although complete blockade was evident at lower doses in male rats. These results support previous findings regarding the prominent role of serotonergic activities underlying LSDs discriminative stimulus effects in male rats and generalize these findings to female rats. In consideration of the rising popularity in psychedelic-assisted psychotherapy, further research may be warranted to evaluate possible sex differences in the behavioral and subjective effects of LSD.
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12
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Pokorny T, Duerler P, Seifritz E, Vollenweider FX, Preller KH. LSD acutely impairs working memory, executive functions, and cognitive flexibility, but not risk-based decision-making. Psychol Med 2020; 50:2255-2264. [PMID: 31500679 DOI: 10.1017/s0033291719002393] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Psychiatric and neurodegenerative illnesses are characterized by cognitive impairments, in particular deficits in working memory, decision-making, and executive functions including cognitive flexibility. However, the neuropharmacology of these cognitive functions is poorly understood. The serotonin (5-HT) 2A receptor might be a promising candidate for the modulation of cognitive processes. However, pharmacological studies investigating the role of this receptor system in humans are rare. Recent evidence demonstrates that the effects of Lysergic acid diethylamide (LSD) are mediated via agonistic action at the 5-HT2A receptor. Yet, the effects of LSD on specific cognitive domains using standardized neuropsychological test have not been studied. METHODS We examined the acute effects of LSD (100 µg) alone and in combination with the 5-HT2A antagonist ketanserin (40 mg) on cognition, employing a double-blind, randomized, placebo-controlled, within-subject design in 25 healthy participants. Executive functions, cognitive flexibility, spatial working memory, and risk-based decision-making were examined by the Intra/Extra-Dimensional shift task (IED), Spatial Working Memory task (SWM), and Cambridge Gambling Task (CGT) of the Cambridge Neuropsychological Test Automated Battery. RESULTS Compared to placebo, LSD significantly impaired executive functions, cognitive flexibility, and working memory on the IED and SWM, but did not influence the quality of decision-making and risk taking on the CGT. Pretreatment with the 5-HT2A antagonist ketanserin normalized all LSD-induced cognitive deficits. CONCLUSIONS The present findings highlight the role of the 5-HT2A receptor system in executive functions and working memory and suggest that specific 5-HT2A antagonists may be relevant for improving cognitive dysfunctions in psychiatric disorders.
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Affiliation(s)
- Thomas Pokorny
- Neuropsychopharmacology and Brain Imaging, Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zurich, Zurich, Switzerland
- Heffter Research Center Zurich, Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zurich, Zurich, Switzerland
| | - Patricia Duerler
- Neuropsychopharmacology and Brain Imaging, Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zurich, Zurich, Switzerland
- Heffter Research Center Zurich, Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zurich, Zurich, Switzerland
| | - Erich Seifritz
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zurich, Zurich, Switzerland
| | - Franz X Vollenweider
- Neuropsychopharmacology and Brain Imaging, Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zurich, Zurich, Switzerland
- Heffter Research Center Zurich, Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zurich, Zurich, Switzerland
| | - Katrin H Preller
- Neuropsychopharmacology and Brain Imaging, Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zurich, Zurich, Switzerland
- Heffter Research Center Zurich, Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zurich, Zurich, Switzerland
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13
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Tutone M, Almerico AM. The In Silico Fischer Lock-and-Key Model: The Combined Use of Molecular Descriptors and Docking Poses for the Repurposing of Old Drugs. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2019; 2089:29-39. [PMID: 31773645 DOI: 10.1007/978-1-0716-0163-1_2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Not always lead compound and/or derivatives are suitable for the specific biological target for which they are designed but, in some cases, discarded compounds proved to be good binders for other biological targets; therefore, drug repurposing constitute a valid alternative to avoid waste of human and financial resources. Our virtual lock-and-key methods, VLKA and Conf-VLKA, furnish a strong support to predict the efficacy of a designed drug a priori its biological evaluation, or the correct biological target for a set of the selected compounds, allowing thus the repurposing of known and unknown, active and inactive compounds.
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Affiliation(s)
- Marco Tutone
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University di Palermo, Palermo, Italy.
| | - Anna Maria Almerico
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University di Palermo, Palermo, Italy
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14
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Popik P, Krawczyk M, Kuziak A, Bugno R, Hogendorf A, Staroń J, Nikiforuk A. Serotonin type 5A receptor antagonists inhibit D-lysergic acid diethylamide discriminatory cue in rats. J Psychopharmacol 2019; 33:1447-1455. [PMID: 31452444 DOI: 10.1177/0269881119867603] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
PURPOSE Like other psychedelics, D-lysergic acid diethylamide (LSD) affects numerous serotonin receptors, and according to the current dogma, the 5-HT2A receptors are considered the main target for its hallucinogenic effects. LSD, however, also displays agonistic activity at the 5-HT5A receptors, which mediate some of LSD-induced behavioural effects. METHODS Using male Sprague Dawley rats, we examined the effects of 5-HT2A and 5-HT5A receptor antagonists on LSD-induced stimulus control in the two-lever drug discrimination test using a FR10 schedule of reinforcement. RESULTS In animals trained to discriminate 0.08 mg/kg LSD from vehicle 15 minutes after injection, LSD produced dose-related increases in response, with an ED50 (±95% confidence limits) of 0.0384 (± 0.025-0.051) mg/kg). LSD-like responses were observed when the training dose of LSD was given 5-30 but not 90 minutes before the test. Confirming earlier reports, the 5-HT antagonist ketanserin (2 mg/kg) attenuated the LSD response in 50% of rats, and due to pretreatment with 0.2 and 2 mg/kg MDL 100907, 63% and 67% of animals, respectively, failed to select the LSD lever. We then investigated the effects of two 5-HT5A receptor antagonists, and we found that 56% and 60% of rats pretreated with 3 and 10 mg/kg SB 699551, respectively, failed to select the LSD lever. Due to pretreatment with 0.01 mg/kg ASP 5736, 58% of rats did not select the LSD lever. This dose also reduced the response rate but not the number of rats failing to complete the test. CONCLUSIONS The present results suggest that antagonists of the 5-HT5A receptor may inhibit subjective effects of LSD in rats.
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Affiliation(s)
- Piotr Popik
- Behavioral Neuroscience and Drug Development, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
| | - Martyna Krawczyk
- Behavioral Neuroscience and Drug Development, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
| | - Agata Kuziak
- Behavioral Neuroscience and Drug Development, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
| | - Ryszard Bugno
- Department of Medicinal Chemistry, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
| | - Adam Hogendorf
- Department of Medicinal Chemistry, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
| | - Jakub Staroń
- Department of Medicinal Chemistry, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
| | - Agnieszka Nikiforuk
- Behavioral Neuroscience and Drug Development, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
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15
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Yanakieva S, Polychroni N, Family N, Williams LTJ, Luke DP, Terhune DB. The effects of microdose LSD on time perception: a randomised, double-blind, placebo-controlled trial. Psychopharmacology (Berl) 2019; 236:1159-1170. [PMID: 30478716 PMCID: PMC6591199 DOI: 10.1007/s00213-018-5119-x] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 11/09/2018] [Indexed: 12/11/2022]
Abstract
RATIONALE Previous research demonstrating that lysergic acid diethylamide (LSD) produces alterations in time perception has implications for its impact on conscious states and a range of psychological functions that necessitate precise interval timing. However, interpretation of this research is hindered by methodological limitations and an inability to dissociate direct neurochemical effects on interval timing from indirect effects attributable to altered states of consciousness. METHODS We conducted a randomised, double-blind, placebo-controlled study contrasting oral administration of placebo with three microdoses of LSD (5, 10, and 20 μg) in older adults. Subjective drug effects were regularly recorded and interval timing was assessed using a temporal reproduction task spanning subsecond and suprasecond intervals. RESULTS LSD conditions were not associated with any robust changes in self-report indices of perception, mentation, or concentration. LSD reliably produced over-reproduction of temporal intervals of 2000 ms and longer with these effects most pronounced in the 10 μg dose condition. Hierarchical regression analyses indicated that LSD-mediated over-reproduction was independent of marginal differences in self-reported drug effects across conditions. CONCLUSIONS These results suggest that microdose LSD produces temporal dilation of suprasecond intervals in the absence of subjective alterations of consciousness.
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Affiliation(s)
- Steliana Yanakieva
- Department of Psychology, Goldsmiths, University of London, 8 Lewisham Way, New Cross, London, SE14 6NW, UK
| | - Naya Polychroni
- Department of Psychology, Goldsmiths, University of London, 8 Lewisham Way, New Cross, London, SE14 6NW, UK
| | | | - Luke T J Williams
- Eleusis Pharmaceuticals Ltd, London, UK
- Centre for Psychiatry, Division of Brain Sciences, Imperial College London, London, UK
| | - David P Luke
- Department of Psychology, Social Work, & Counselling, University of Greenwich, London, UK
| | - Devin B Terhune
- Department of Psychology, Goldsmiths, University of London, 8 Lewisham Way, New Cross, London, SE14 6NW, UK.
- Department of Experimental Psychology, University of Oxford, Oxford, UK.
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16
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Effective connectivity changes in LSD-induced altered states of consciousness in humans. Proc Natl Acad Sci U S A 2019; 116:2743-2748. [PMID: 30692255 PMCID: PMC6377471 DOI: 10.1073/pnas.1815129116] [Citation(s) in RCA: 143] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Lysergic acid diethylamide (LSD) is a psychedelic drug that reliably induces an altered state of consciousness. Interest in psychedelic compounds is growing due to their remarkable potential for understanding altered neural states and potential clinical applications. However, there are major knowledge gaps regarding LSD’s neuropharmacology. Using cutting-edge neuroimaging methods we investigated directed connectivity between cortico–striato–thalamo-cortical (CSTC) regions after administration of LSD together with the specific role of the serotonin 2A receptor. Our results provide evidence that LSD alters directed connectivity within CSTC pathways in humans, suggesting that a disintegration of information processing within these loops is underlying the psychedelic state. These results inform the neurobiology of altered states of consciousness with critical implications for rational development of novel treatments. Psychedelics exert unique effects on human consciousness. The thalamic filter model suggests that core effects of psychedelics may result from gating deficits, based on a disintegration of information processing within cortico–striato–thalamo-cortical (CSTC) feedback loops. To test this hypothesis, we characterized changes in directed (effective) connectivity between selected CTSC regions after acute administration of lysergic acid diethylamide (LSD), and after pretreatment with Ketanserin (a selective serotonin 2A receptor antagonist) plus LSD in a double-blind, randomized, placebo-controlled, cross-over study in 25 healthy participants. We used spectral dynamic causal modeling (DCM) for resting-state fMRI data. Fully connected DCM models were specified for each treatment condition to investigate the connectivity between the following areas: thalamus, ventral striatum, posterior cingulate cortex, and temporal cortex. Our results confirm major predictions proposed in the CSTC model and provide evidence that LSD alters effective connectivity within CSTC pathways that have been implicated in the gating of sensory and sensorimotor information to the cortex. In particular, LSD increased effective connectivity from the thalamus to the posterior cingulate cortex in a way that depended on serotonin 2A receptor activation, and decreased effective connectivity from the ventral striatum to the thalamus independently of serotonin 2A receptor activation. Together, these results advance our mechanistic understanding of the action of psychedelics in health and disease. This is important for the development of new pharmacological therapeutics and also increases our understanding of the mechanisms underlying the potential clinical efficacy of psychedelics.
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17
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Zamberlan F, Sanz C, Martínez Vivot R, Pallavicini C, Erowid F, Erowid E, Tagliazucchi E. The Varieties of the Psychedelic Experience: A Preliminary Study of the Association Between the Reported Subjective Effects and the Binding Affinity Profiles of Substituted Phenethylamines and Tryptamines. Front Integr Neurosci 2018; 12:54. [PMID: 30467466 PMCID: PMC6235949 DOI: 10.3389/fnint.2018.00054] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 10/15/2018] [Indexed: 02/05/2023] Open
Abstract
Classic psychedelics are substances of paramount cultural and neuroscientific importance. A distinctive feature of psychedelic drugs is the wide range of potential subjective effects they can elicit, known to be deeply influenced by the internal state of the user ("set") and the surroundings ("setting"). The observation of cross-tolerance and a series of empirical studies in humans and animal models support agonism at the serotonin (5-HT)2A receptor as a common mechanism for the action of psychedelics. The diversity of subjective effects elicited by different compounds has been attributed to the variables of "set" and "setting," to the binding affinities for other 5-HT receptor subtypes, and to the heterogeneity of transduction pathways initiated by conformational receptor states as they interact with different ligands ("functional selectivity"). Here we investigate the complementary (i.e., not mutually exclusive) possibility that such variety is also related to the binding affinity for a range of neurotransmitters and monoamine transporters including (but not limited to) 5-HT receptors. Building on two independent binding affinity datasets (compared to "in silico" estimates) in combination with natural language processing tools applied to a large repository of reports of psychedelic experiences (Erowid's Experience Vaults), we obtained preliminary evidence supporting that the similarity between the binding affinity profiles of psychoactive substituted phenethylamines and tryptamines is correlated with the semantic similarity of the associated reports. We also showed that the highest correlation was achieved by considering the combined binding affinity for the 5-HT, dopamine (DA), glutamate, muscarinic and opioid receptors and for the Ca+ channel. Applying dimensionality reduction techniques to the reports, we linked the compounds, receptors, transporters and the Ca+ channel to distinct fingerprints of the reported subjective effects. To the extent that the existing binding affinity data is based on a low number of displacement curves that requires further replication, our analysis produced preliminary evidence consistent with the involvement of different binding sites in the reported subjective effects elicited by psychedelics. Beyond the study of this particular class of drugs, we provide a methodological framework to explore the relationship between the binding affinity profiles and the reported subjective effects of other psychoactive compounds.
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Affiliation(s)
- Federico Zamberlan
- Departamento de Física, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Física de Buenos Aires (IFIBA) and National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina
| | - Camila Sanz
- Departamento de Física, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Rocío Martínez Vivot
- Instituto de Física de Buenos Aires (IFIBA) and National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina
- Instituto de Investigaciones Biomédicas (BIOMED) and Technical Research Council (CONICET), Buenos Aires, Argentina
| | - Carla Pallavicini
- Instituto de Física de Buenos Aires (IFIBA) and National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina
- Fundación Para la Lucha contra las Enfermedades Neurológicas de la Infancia (FLENI), Buenos Aires, Argentina
| | - Fire Erowid
- Erowid Center, Grass Valley, CA, United States
| | | | - Enzo Tagliazucchi
- Departamento de Física, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Física de Buenos Aires (IFIBA) and National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina
- UMR7225 Institut du Cerveau et de la Moelle épinière (ICM), Paris, France
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18
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Preller KH, Burt JB, Ji JL, Schleifer CH, Adkinson BD, Stämpfli P, Seifritz E, Repovs G, Krystal JH, Murray JD, Vollenweider FX, Anticevic A. Changes in global and thalamic brain connectivity in LSD-induced altered states of consciousness are attributable to the 5-HT2A receptor. eLife 2018; 7:35082. [PMID: 30355445 PMCID: PMC6202055 DOI: 10.7554/elife.35082] [Citation(s) in RCA: 202] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2018] [Accepted: 09/09/2018] [Indexed: 12/15/2022] Open
Abstract
Background: Lysergic acid diethylamide (LSD) has agonist activity at various serotonin (5-HT) and dopamine receptors. Despite the therapeutic and scientific interest in LSD, specific receptor contributions to its neurobiological effects remain unknown. Methods: We therefore conducted a double-blind, randomized, counterbalanced, cross-over studyduring which 24 healthy human participants received either (i) placebo+placebo, (ii) placebo+LSD (100 µg po), or (iii) Ketanserin, a selective 5-HT2A receptor antagonist,+LSD. We quantified resting-state functional connectivity via a data-driven global brain connectivity method and compared it to cortical gene expression maps. Results: LSD reduced associative, but concurrently increased sensory-somatomotor brain-wide and thalamic connectivity. Ketanserin fully blocked the subjective and neural LSD effects. Whole-brain spatial patterns of LSD effects matched 5-HT2A receptor cortical gene expression in humans. Conclusions: Together, these results strongly implicate the 5-HT2A receptor in LSD’s neuropharmacology. This study therefore pinpoints the critical role of 5-HT2A in LSD’s mechanism, which informs its neurobiology and guides rational development of psychedelic-based therapeutics. Funding: Funded by the Swiss National Science Foundation, the Swiss Neuromatrix Foundation, the Usona Institute, the NIH, the NIAA, the NARSAD Independent Investigator Grant, the Yale CTSA grant, and the Slovenian Research Agency. Clinical trial number: NCT02451072. The psychedelic drug LSD alters thinking and perception. Users can experience hallucinations, in which they, for example, see things that are not there. Colors, sounds and objects can appear distorted, and time can seem to speed up or slow down. These changes bear some resemblance to the changes in thinking and perception that occur in certain psychiatric disorders, such as schizophrenia. Studying how LSD affects the brain could thus offer insights into the mechanisms underlying these conditions. There is also evidence that LSD itself could help to reduce the symptoms of depression and anxiety disorders. Preller et al. have now used brain imaging to explore the effects of LSD on the brains of healthy volunteers. This revealed that LSD reduced communication among brain areas involved in planning and decision-making, but it increased communication between areas involved in sensation and movement. Volunteers whose brains showed the most communication between sensory and movement areas also reported the strongest effects of LSD on their thinking and perception. Preller et al. also found that another drug called Ketanserin prevented LSD from altering how different brain regions communicate. It also prevented LSD from inducing changes in thinking and perception. Ketanserin blocks a protein called the serotonin 2A receptor, which is activated by a brain chemical called serotonin that, amongst other roles, helps to regulate mood. By mapping the location of the gene that produces the serotonin 2A receptor, Preller et al. showed that the receptor is present in brain regions that show altered communication after LSD intake, therefore pinpointing the importance of this receptor in the effects of LSD. Psychiatric disorders that produce psychotic symptoms affect vast numbers of people worldwide. Further research into how LSD affects the brain could help us to better understand how such symptoms arise, and may also lead to the development of more effective treatments for a range of mental health conditions.
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Affiliation(s)
- Katrin H Preller
- Neuropsychopharmacology and Brain Imaging, Department of Psychiatry, Psychotherapy and Psychosomatics, University Hospital for Psychiatry Zurich, Zurich, Switzerland.,Department of Psychiatry, Yale University School of Medicine, New Haven, United States
| | - Joshua B Burt
- Department of Psychiatry, Yale University School of Medicine, New Haven, United States.,Department of Physics, Yale University, New Haven, United States
| | - Jie Lisa Ji
- Department of Psychiatry, Yale University School of Medicine, New Haven, United States
| | - Charles H Schleifer
- Department of Psychiatry, Yale University School of Medicine, New Haven, United States
| | - Brendan D Adkinson
- Department of Psychiatry, Yale University School of Medicine, New Haven, United States
| | - Philipp Stämpfli
- Department of Psychiatry, Psychotherapy and Psychosomatics, University Hospital for Psychiatry Zurich, Zurich, Switzerland
| | - Erich Seifritz
- Department of Psychiatry, Psychotherapy and Psychosomatics, University Hospital for Psychiatry Zurich, Zurich, Switzerland
| | - Grega Repovs
- Mind and Brain Lab, Department of Psychology, University of Ljubljana, Ljubljana, Slovenia
| | - John H Krystal
- Department of Psychiatry, Yale University School of Medicine, New Haven, United States
| | - John D Murray
- Department of Psychiatry, Yale University School of Medicine, New Haven, United States.,Department of Physics, Yale University, New Haven, United States.,Department of Neuroscience, Yale University School of Medicine, New Haven, United States
| | - Franz X Vollenweider
- Neuropsychopharmacology and Brain Imaging, Department of Psychiatry, Psychotherapy and Psychosomatics, University Hospital for Psychiatry Zurich, Zurich, Switzerland
| | - Alan Anticevic
- Department of Psychiatry, Yale University School of Medicine, New Haven, United States
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19
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Nichols DE. Dark Classics in Chemical Neuroscience: Lysergic Acid Diethylamide (LSD). ACS Chem Neurosci 2018; 9:2331-2343. [PMID: 29461039 DOI: 10.1021/acschemneuro.8b00043] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Lysergic acid diethylamide (LSD) is one of the most potent psychoactive agents known, producing dramatic alterations of consciousness after submilligram (≥20 μg) oral doses. Following the accidental discovery of its potent psychoactive effects in 1943, it was supplied by Sandoz Laboratories as an experimental drug that might be useful as an adjunct for psychotherapy, or to give psychiatrists insight into the mental processes in their patients. The finding of serotonin in the mammalian brain in 1953, and its structural resemblance to LSD, quickly led to ideas that serotonin in the brain might be involved in mental disorders, initiating rapid research interest in the neurochemistry of serotonin. LSD proved to be physiologically very safe and nonaddictive, with a very low incidence of adverse events when used in controlled experiments. Widely hailed by psychiatry as a breakthrough in the 1950s and early 1960s, clinical research with LSD ended by about 1970, when it was formally placed into Schedule 1 of the Controlled Substances Act of 1970 following its growing popularity as a recreational drug. Within the past 5 years, clinical research with LSD has begun in Europe, but there has been none in the United States. LSD is proving to be a powerful tool to help understand brain dynamics when combined with modern brain imaging methods. It remains to be seen whether therapeutic value for LSD can be confirmed in controlled clinical trials, but promising results have been obtained in small pilot trials of depression, anxiety, and addictions using psilocybin, a related psychedelic molecule.
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Affiliation(s)
- David E. Nichols
- Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
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20
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Liechti ME. Modern Clinical Research on LSD. Neuropsychopharmacology 2017; 42:2114-2127. [PMID: 28447622 PMCID: PMC5603820 DOI: 10.1038/npp.2017.86] [Citation(s) in RCA: 115] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 04/19/2017] [Accepted: 04/20/2017] [Indexed: 12/11/2022]
Abstract
All modern clinical studies using the classic hallucinogen lysergic acid diethylamide (LSD) in healthy subjects or patients in the last 25 years are reviewed herein. There were five recent studies in healthy participants and one in patients. In a controlled setting, LSD acutely induced bliss, audiovisual synesthesia, altered meaning of perceptions, derealization, depersonalization, and mystical experiences. These subjective effects of LSD were mediated by the 5-HT2A receptor. LSD increased feelings of closeness to others, openness, trust, and suggestibility. LSD impaired the recognition of sad and fearful faces, reduced left amygdala reactivity to fearful faces, and enhanced emotional empathy. LSD increased the emotional response to music and the meaning of music. LSD acutely produced deficits in sensorimotor gating, similar to observations in schizophrenia. LSD had weak autonomic stimulant effects and elevated plasma cortisol, prolactin, and oxytocin levels. Resting-state functional magnetic resonance studies showed that LSD acutely reduced the integrity of functional brain networks and increased connectivity between networks that normally are more dissociated. LSD increased functional thalamocortical connectivity and functional connectivity of the primary visual cortex with other brain areas. The latter effect was correlated with subjective hallucinations. LSD acutely induced global increases in brain entropy that were associated with greater trait openness 14 days later. In patients with anxiety associated with life-threatening disease, anxiety was reduced for 2 months after two doses of LSD. In medical settings, no complications of LSD administration were observed. These data should contribute to further investigations of the therapeutic potential of LSD in psychiatry.
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Affiliation(s)
- Matthias E Liechti
- Psychopharmacology Research, Clinical Pharmacology and Toxicology, Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland
- Psychopharmacology Research, Clinical Pharmacology and Toxicology, Department of Clinical Research, University Hospital Basel, University of Basel, Basel, Switzerland
- Psychopharmacology Research, Clinical Pharmacology and Toxicology, Department of Internal Medicine, University Hospital Basel, University of Basel, Basel, Switzerland
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21
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Kraehenmann R, Pokorny D, Vollenweider L, Preller KH, Pokorny T, Seifritz E, Vollenweider FX. Dreamlike effects of LSD on waking imagery in humans depend on serotonin 2A receptor activation. Psychopharmacology (Berl) 2017; 234:2031-2046. [PMID: 28386699 DOI: 10.1007/s00213-017-4610-0] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 03/20/2017] [Indexed: 01/15/2023]
Abstract
RATIONALE Accumulating evidence indicates that the mixed serotonin and dopamine receptor agonist lysergic acid diethylamide (LSD) induces an altered state of consciousness that resembles dreaming. OBJECTIVES This study aimed to test the hypotheses that LSD produces dreamlike waking imagery and that this imagery depends on 5-HT2A receptor activation and is related to subjective drug effects. METHODS Twenty-five healthy subjects performed an audiorecorded guided mental imagery task 7 h after drug administration during three drug conditions: placebo, LSD (100 mcg orally) and LSD together with the 5-HT2A receptor antagonist ketanserin (40 mg orally). Cognitive bizarreness of guided mental imagery reports was quantified as a standardised formal measure of dream mentation. State of consciousness was evaluated using the Altered State of Consciousness (5D-ASC) questionnaire. RESULTS LSD, compared with placebo, significantly increased cognitive bizarreness (p < 0.001). The LSD-induced increase in cognitive bizarreness was positively correlated with the LSD-induced loss of self-boundaries and cognitive control (p < 0.05). Both LSD-induced increases in cognitive bizarreness and changes in state of consciousness were fully blocked by ketanserin. CONCLUSIONS LSD produced mental imagery similar to dreaming, primarily via activation of the 5-HT2A receptor and in relation to loss of self-boundaries and cognitive control. Future psychopharmacological studies should assess the differential contribution of the D2/D1 and 5-HT1A receptors to cognitive bizarreness.
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Affiliation(s)
- Rainer Kraehenmann
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zurich, Zurich, Switzerland. .,Neuropsychopharmacology and Brain Imaging, Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zurich, Lenggstrasse 31, 8032, Zurich, Switzerland.
| | - Dan Pokorny
- Department of Psychosomatic Medicine and Psychotherapy, University of Ulm, Ulm, Germany
| | - Leonie Vollenweider
- Neuropsychopharmacology and Brain Imaging, Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zurich, Lenggstrasse 31, 8032, Zurich, Switzerland
| | - Katrin H Preller
- Neuropsychopharmacology and Brain Imaging, Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zurich, Lenggstrasse 31, 8032, Zurich, Switzerland
| | - Thomas Pokorny
- Neuropsychopharmacology and Brain Imaging, Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zurich, Lenggstrasse 31, 8032, Zurich, Switzerland
| | - Erich Seifritz
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zurich, Zurich, Switzerland
| | - Franz X Vollenweider
- Neuropsychopharmacology and Brain Imaging, Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zurich, Lenggstrasse 31, 8032, Zurich, Switzerland
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Abstract
Hallucinogens comprise a diverse collection of chemicals with multifarious receptor actions in the central nervous system. Preclinical drug screening methods have proven invaluable in the evaluation and characterization of hallucinogen psychopharmacology. Used in concert with structural chemistry and receptor pharmacology methods, preclinical drug discrimination research has informed our current understanding of hallucinogens and the neurochemical receptor mechanisms responsible for their interoceptive stimulus effects. This chapter summarizes the strengths and limitations of drug discrimination as an in vivo drug detection method and offers a brief review of historical and contemporary drug discrimination research with classical hallucinogens.
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23
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De Gregorio D, Comai S, Posa L, Gobbi G. d-Lysergic Acid Diethylamide (LSD) as a Model of Psychosis: Mechanism of Action and Pharmacology. Int J Mol Sci 2016; 17:E1953. [PMID: 27886063 PMCID: PMC5133947 DOI: 10.3390/ijms17111953] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 10/25/2016] [Accepted: 11/14/2016] [Indexed: 12/15/2022] Open
Abstract
d-Lysergic Acid Diethylamide (LSD) is known for its hallucinogenic properties and psychotic-like symptoms, especially at high doses. It is indeed used as a pharmacological model of psychosis in preclinical research. The goal of this review was to understand the mechanism of action of psychotic-like effects of LSD. We searched Pubmed, Web of Science, Scopus, Google Scholar and articles' reference lists for preclinical studies regarding the mechanism of action involved in the psychotic-like effects induced by LSD. LSD's mechanism of action is pleiotropic, primarily mediated by the serotonergic system in the Dorsal Raphe, binding the 5-HT2A receptor as a partial agonist and 5-HT1A as an agonist. LSD also modulates the Ventral Tegmental Area, at higher doses, by stimulating dopamine D₂, Trace Amine Associate receptor 1 (TAAR₁) and 5-HT2A. More studies clarifying the mechanism of action of the psychotic-like symptoms or psychosis induced by LSD in humans are needed. LSD's effects are mediated by a pleiotropic mechanism involving serotonergic, dopaminergic, and glutamatergic neurotransmission. Thus, the LSD-induced psychosis is a useful model to test the therapeutic efficacy of potential novel antipsychotic drugs, particularly drugs with dual serotonergic and dopaminergic (DA) mechanism or acting on TAAR₁ receptors.
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MESH Headings
- Animals
- Antipsychotic Agents/pharmacology
- Behavior, Animal/drug effects
- Disease Models, Animal
- Dopamine/metabolism
- Dopamine/pharmacology
- Dorsal Raphe Nucleus/drug effects
- Dorsal Raphe Nucleus/metabolism
- Dorsal Raphe Nucleus/physiopathology
- Drug Evaluation, Preclinical
- Hallucinogens/metabolism
- Hallucinogens/pharmacology
- Humans
- Lysergic Acid Diethylamide/metabolism
- Lysergic Acid Diethylamide/pharmacology
- Psychotic Disorders/drug therapy
- Psychotic Disorders/metabolism
- Psychotic Disorders/physiopathology
- Rats
- Receptor, Serotonin, 5-HT1A/metabolism
- Receptor, Serotonin, 5-HT2A/metabolism
- Receptors, Dopamine/metabolism
- Receptors, G-Protein-Coupled/metabolism
- Receptors, Glutamate/metabolism
- Serotonin Receptor Agonists/metabolism
- Serotonin Receptor Agonists/pharmacology
- Synaptic Transmission/drug effects
- Ventral Tegmental Area/drug effects
- Ventral Tegmental Area/metabolism
- Ventral Tegmental Area/physiopathology
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Affiliation(s)
- Danilo De Gregorio
- Neurobiological Psychiatry Unit, McGill University, Montreal, QC H3A 1A1, Canada.
| | - Stefano Comai
- Division of Neuroscience, San Raffaele Scientific Institute and Vita-Salute University, 20132 Milan, Italy.
| | - Luca Posa
- Neurobiological Psychiatry Unit, McGill University, Montreal, QC H3A 1A1, Canada.
| | - Gabriella Gobbi
- Neurobiological Psychiatry Unit, McGill University, Montreal, QC H3A 1A1, Canada.
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24
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Tutone M, Perricone U, Almerico AM. Conf-VLKA: A structure-based revisitation of the Virtual Lock-and-key Approach. J Mol Graph Model 2016; 71:50-57. [PMID: 27842227 DOI: 10.1016/j.jmgm.2016.11.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 11/03/2016] [Accepted: 11/07/2016] [Indexed: 02/02/2023]
Abstract
In a previous work, we developed the in house Virtual Lock-and-Key Approach (VLKA) in order to evaluate target assignment starting from molecular descriptors calculated on known inhibitors used as an information source. This protocol was able to predict the correct biological target for the whole dataset with a good degree of reliability (80%), and proved experimentally, which was useful for the target fishing of unknown compounds. In this paper, we tried to remodel the previous in house developed VLKA in a more sophisticated one in order to evaluate the influence of 3D conformation of ligands on the accuracy of the prediction. We applied the same previous algorithm of scoring and ranking but, this time, combining it with a structure-based approach as docking. For this reason, we retrieved from the RCSB Protein Data Bank (PDB), the available 3D structures of the biological targets included into the previous work, and we used them to calculate poses of the 7352 dataset compounds in the VLKA biological targets. First, docking protocol has been used to retrieve docking scores, then, from the docked poses of each molecule, 3D-descriptors were calculated (Conf-VLKA), While the use of the simple docking scores proved to be inadequate to improve compounds classification, the Conf-VLKA showed some interesting variations compared to the original VLKA, especially for targets whose ligands present a high number of rotamers. This work represent a first preliminary study to be completed using other techniques such as induced fit docking or molecular dynamics structure clustering to take into account the protein side chains adaptation to ligands structures.
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Affiliation(s)
- Marco Tutone
- Dipartimento di Scienze e Tecnologie Biologiche Chimiche e Farmaceutiche (STEBICEF), Università di Palermo, Via Archirafi 28, Palermo, Italy.
| | - Ugo Perricone
- Dipartimento di Scienze e Tecnologie Biologiche Chimiche e Farmaceutiche (STEBICEF), Università di Palermo, Via Archirafi 28, Palermo, Italy
| | - Anna Maria Almerico
- Dipartimento di Scienze e Tecnologie Biologiche Chimiche e Farmaceutiche (STEBICEF), Università di Palermo, Via Archirafi 28, Palermo, Italy
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25
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The hallucinogen d -lysergic diethylamide (LSD) decreases dopamine firing activity through 5-HT 1A , D 2 and TAAR 1 receptors. Pharmacol Res 2016; 113:81-91. [DOI: 10.1016/j.phrs.2016.08.022] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 06/12/2016] [Accepted: 08/16/2016] [Indexed: 10/21/2022]
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Abstract
Psychedelics (serotonergic hallucinogens) are powerful psychoactive substances that alter perception and mood and affect numerous cognitive processes. They are generally considered physiologically safe and do not lead to dependence or addiction. Their origin predates written history, and they were employed by early cultures in many sociocultural and ritual contexts. After the virtually contemporaneous discovery of (5R,8R)-(+)-lysergic acid-N,N-diethylamide (LSD)-25 and the identification of serotonin in the brain, early research focused intensively on the possibility that LSD and other psychedelics had a serotonergic basis for their action. Today there is a consensus that psychedelics are agonists or partial agonists at brain serotonin 5-hydroxytryptamine 2A receptors, with particular importance on those expressed on apical dendrites of neocortical pyramidal cells in layer V. Several useful rodent models have been developed over the years to help unravel the neurochemical correlates of serotonin 5-hydroxytryptamine 2A receptor activation in the brain, and a variety of imaging techniques have been employed to identify key brain areas that are directly affected by psychedelics. Recent and exciting developments in the field have occurred in clinical research, where several double-blind placebo-controlled phase 2 studies of psilocybin-assisted psychotherapy in patients with cancer-related psychosocial distress have demonstrated unprecedented positive relief of anxiety and depression. Two small pilot studies of psilocybin-assisted psychotherapy also have shown positive benefit in treating both alcohol and nicotine addiction. Recently, blood oxygen level-dependent functional magnetic resonance imaging and magnetoencephalography have been employed for in vivo brain imaging in humans after administration of a psychedelic, and results indicate that intravenously administered psilocybin and LSD produce decreases in oscillatory power in areas of the brain's default mode network.
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Affiliation(s)
- David E Nichols
- Eschelman School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina
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27
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Kyzar EJ, Kalueff AV. Exploring Hallucinogen Pharmacology and Psychedelic Medicine with Zebrafish Models. Zebrafish 2016; 13:379-90. [PMID: 27002655 DOI: 10.1089/zeb.2016.1251] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
After decades of sociopolitical obstacles, the field of psychiatry is experiencing a revived interest in the use of hallucinogenic agents to treat brain disorders. Along with the use of ketamine for depression, recent pilot studies have highlighted the efficacy of classic serotonergic hallucinogens, such as lysergic acid diethylamide and psilocybin, in treating addiction, post-traumatic stress disorder, and anxiety. However, many basic pharmacological and toxicological questions remain unanswered with regard to these compounds. In this study, we discuss psychedelic medicine as well as the behavioral and toxicological effects of hallucinogenic drugs in zebrafish. We emphasize this aquatic organism as a model ideally suited to assess both the potential toxic and therapeutic effects of major known classes of hallucinogenic compounds. In addition, novel drugs with hallucinogenic properties can be efficiently screened using zebrafish models. Well-designed preclinical studies utilizing zebrafish can contribute to the reemerging treatment paradigm of psychedelic medicine, leading to new avenues of clinical exploration for psychiatric disorders.
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Affiliation(s)
- Evan J Kyzar
- 1 Department of Psychiatry, College of Medicine, University of Illinois at Chicago , Chicago, Illinois
| | - Allan V Kalueff
- 2 Research Institute for Marine Drugs and Nutrition, College of Food Science and Technology, Guangdong Ocean University (GDOU) , Zhanjiang, China .,3 ZENEREI Institute , Slidell, Louisiana.,4 Institute of Translational Biomedicine, St. Petersburg State University , St. Petersburg, Russia .,5 Institutes of Chemical Technology and Natural Sciences, Ural Federal University , Ekaterinburg, Russia .,6 The International Zebrafish Neuroscience Research Consortium (ZNRC) , Slidell, Louisiana
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28
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Korpi ER, den Hollander B, Farooq U, Vashchinkina E, Rajkumar R, Nutt DJ, Hyytiä P, Dawe GS. Mechanisms of Action and Persistent Neuroplasticity by Drugs of Abuse. Pharmacol Rev 2015; 67:872-1004. [DOI: 10.1124/pr.115.010967] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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Halberstadt AL. Recent advances in the neuropsychopharmacology of serotonergic hallucinogens. Behav Brain Res 2015; 277:99-120. [PMID: 25036425 PMCID: PMC4642895 DOI: 10.1016/j.bbr.2014.07.016] [Citation(s) in RCA: 191] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Revised: 07/07/2014] [Accepted: 07/08/2014] [Indexed: 12/12/2022]
Abstract
Serotonergic hallucinogens, such as (+)-lysergic acid diethylamide, psilocybin, and mescaline, are somewhat enigmatic substances. Although these drugs are derived from multiple chemical families, they all produce remarkably similar effects in animals and humans, and they show cross-tolerance. This article reviews the evidence demonstrating the serotonin 5-HT2A receptor is the primary site of hallucinogen action. The 5-HT2A receptor is responsible for mediating the effects of hallucinogens in human subjects, as well as in animal behavioral paradigms such as drug discrimination, head twitch response, prepulse inhibition of startle, exploratory behavior, and interval timing. Many recent clinical trials have yielded important new findings regarding the psychopharmacology of these substances. Furthermore, the use of modern imaging and electrophysiological techniques is beginning to help unravel how hallucinogens work in the brain. Evidence is also emerging that hallucinogens may possess therapeutic efficacy.
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Affiliation(s)
- Adam L Halberstadt
- Department of Psychiatry, University of California San Diego, La Jolla, CA, United States.
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30
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Pharmacology of hallucinations: several mechanisms for one single symptom? BIOMED RESEARCH INTERNATIONAL 2014; 2014:307106. [PMID: 24991548 PMCID: PMC4065763 DOI: 10.1155/2014/307106] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 05/11/2014] [Indexed: 01/24/2023]
Abstract
Hallucinations are complex misperceptions, that principally occur in schizophrenia or after intoxication induced by three main classes of drugs: psychostimulants, psychedelics, and dissociative anesthetics. There are at least three different pharmacological ways to induce hallucinations: (1) activation of dopamine D2 receptors (D2Rs) with psychostimulants, (2) activation of serotonin 5HT2A receptors (HT2ARs) with psychedelics, and (3) blockage of glutamate NMDA receptors (NMDARs) with dissociative anesthetics. In schizophrenia, the relative importance of NMDAR and D2R in the occurrence of hallucinations is still debated. Slight clinical differences are observed for each etiology. Thus, we investigated whether the concept of hallucination is homogenous, both clinically and neurobiologically. A narrative review of the literature is proposed to synthesize how the main contributors in the field have approached and tried to solve these outstanding questions. While some authors prefer one explanatory mechanism, others have proposed more integrated theories based on the different pharmacological psychosis models. In this review, such theories are discussed and faced with the clinical data. In addition, the nosological aspects of hallucinations and psychosis are addressed. We suggest that if there may be common neurobiological pathways between the different pharmacological systems that are responsible for the hallucinations, there may also be unique properties of each system, which explains the clinical differences observed.
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31
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Krebs TS, Johansen PØ. Psychedelics and mental health: a population study. PLoS One 2013; 8:e63972. [PMID: 23976938 PMCID: PMC3747247 DOI: 10.1371/journal.pone.0063972] [Citation(s) in RCA: 196] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2012] [Accepted: 04/11/2013] [Indexed: 02/06/2023] Open
Abstract
Background The classical serotonergic psychedelics LSD, psilocybin, mescaline are not known to cause brain damage and are regarded as non-addictive. Clinical studies do not suggest that psychedelics cause long-term mental health problems. Psychedelics have been used in the Americas for thousands of years. Over 30 million people currently living in the US have used LSD, psilocybin, or mescaline. Objective To evaluate the association between the lifetime use of psychedelics and current mental health in the adult population. Method Data drawn from years 2001 to 2004 of the National Survey on Drug Use and Health consisted of 130,152 respondents, randomly selected to be representative of the adult population in the United States. Standardized screening measures for past year mental health included serious psychological distress (K6 scale), mental health treatment (inpatient, outpatient, medication, needed but did not receive), symptoms of eight psychiatric disorders (panic disorder, major depressive episode, mania, social phobia, general anxiety disorder, agoraphobia, posttraumatic stress disorder, and non-affective psychosis), and seven specific symptoms of non-affective psychosis. We calculated weighted odds ratios by multivariate logistic regression controlling for a range of sociodemographic variables, use of illicit drugs, risk taking behavior, and exposure to traumatic events. Results 21,967 respondents (13.4% weighted) reported lifetime psychedelic use. There were no significant associations between lifetime use of any psychedelics, lifetime use of specific psychedelics (LSD, psilocybin, mescaline, peyote), or past year use of LSD and increased rate of any of the mental health outcomes. Rather, in several cases psychedelic use was associated with lower rate of mental health problems. Conclusion We did not find use of psychedelics to be an independent risk factor for mental health problems.
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Affiliation(s)
- Teri S. Krebs
- Department of Neuroscience, Faculty of Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
- * E-mail:
| | - Pål-Ørjan Johansen
- Department of Neuroscience, Faculty of Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
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32
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Páleníček T, Fujáková M, Brunovský M, Horáček J, Gorman I, Balíková M, Rambousek L, Syslová K, Kačer P, Zach P, Bubeníková-Valešová V, Tylš F, Kubešová A, Puskarčíková J, Höschl C. Behavioral, neurochemical and pharmaco-EEG profiles of the psychedelic drug 4-bromo-2,5-dimethoxyphenethylamine (2C-B) in rats. Psychopharmacology (Berl) 2013; 225:75-93. [PMID: 22842791 DOI: 10.1007/s00213-012-2797-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Accepted: 06/25/2012] [Indexed: 11/25/2022]
Abstract
RATIONALE AND OBJECTIVES Behavioral, neurochemical and pharmaco-EEG profiles of a new synthetic drug 4-bromo-2,5-dimethoxyphenethylamine (2C-B) in rats were examined. MATERIALS AND METHODS Locomotor effects, prepulse inhibition (PPI) of acoustic startle reaction (ASR), dopamine and its metabolite levels in nucleus accumbens (NAc), EEG power spectra and coherence in freely moving rats were analysed. Amphetamine was used as a reference compound. RESULTS 2C-B had a biphasic effect on locomotion with initial inhibitory followed by excitatory effect; amphetamine induced only hyperlocomotion. Both drugs induced deficits in the PPI; however they had opposite effects on ASR. 2C-B increased dopamine but decreased 3,4-dihydroxyphenylacetic acid (DOPAC) in the NAc. Low doses of 2C-B induced a decrease in EEG power spectra and coherence. On the contrary, high dose of 2C-B 50 mg/kg had a temporally biphasic effect with an initial decrease followed by an increase in EEG power; decrease as well as increase in EEG coherence was observed. Amphetamine mainly induced an increase in EEG power and coherence in theta and alpha bands. Increases in the theta and alpha power and coherence in 2C-B and amphetamine were temporally linked to an increase in locomotor activity and DA levels in NAc. CONCLUSIONS 2C-B is a centrally active compound similar to other hallucinogens, entactogens and stimulants. Increased dopamine and decreased DOPAC in the NAc may reflect its psychotomimetic and addictive potential and monoaminoxidase inhibition. Alterations in brain functional connectivity reflected the behavioral and neurochemical changes produced by the drug; a correlation between EEG changes and locomotor behavior was observed.
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Affiliation(s)
- Tomáš Páleníček
- Prague Psychiatric Center, Ústavní 91, 181 03 Bohnice, Prague 8, Czech Republic.
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Potential serotonin 5-HT(1A) and dopamine D(4) receptor modulation of the discriminative stimulus effects of amphetamine in rats. Behav Pharmacol 2011; 22:508-15. [PMID: 21814134 DOI: 10.1097/fbp.0b013e328349fc31] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Activation of the dopaminergic system underlies the behavioral effects of (+)-amphetamine, and plays a major role in its discriminative stimulus properties. Although serotonin receptors modulate dopamine levels in the brain, and 5-HT(1A) and 5-HT(2) receptor agonists do not mimic (+)-amphetamine, pretreatment with 5-HT(2A/2C) agonists significantly potentiates the (+)-amphetamine cue. Further, 5-HT(2) antagonists do not modify the discriminative stimulus effect of (+)-amphetamine, but 5-HT(1A) antagonists have never been tested in (+)-amphetamine-trained rats. This study sought to characterize the effects of the 5-HT(1A) antagonist WAY 100635 on (+)-amphetamine-induced discriminative stimulus effects. Male Sprague-Dawley rats were trained in a two-lever, fixed ratio 50, food-reinforced task with (+)-amphetamine sulfate (1.0 mg/kg, i.p., 30 min pretreatment time) as the discriminative stimulus. Substitution and combination tests with WAY 100635 were then performed. WAY 100635 did not produce substitution in amphetamine-trained rats, but significantly increased behavioral disruption. In combination tests 0.4 and 5.4 mg/kg doses of WAY 100635 potentiated the amphetamine cue. We suggest that low doses of WAY 100635 potentiated the (+)-amphetamine cue by blockade of 5-HT(1A) receptors, but stimulation of the dopamine D(4) receptor by higher doses of WAY 100635 may be responsible for potentiation of amphetamine-induced behavioral sensitization. The high percentage of behavioral disruption in substitution tests might suggest that rats trained to discriminate (+)-amphetamine from saline show behavioral sensitization that is not detectable by the drug discrimination assay but may be expressed as hyperactivity and stereotypic behavior that disrupts operant behavior.
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Halberstadt AL, Geyer MA. Multiple receptors contribute to the behavioral effects of indoleamine hallucinogens. Neuropharmacology 2011; 61:364-81. [PMID: 21256140 PMCID: PMC3110631 DOI: 10.1016/j.neuropharm.2011.01.017] [Citation(s) in RCA: 233] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2010] [Revised: 12/03/2010] [Accepted: 01/10/2011] [Indexed: 10/18/2022]
Abstract
Serotonergic hallucinogens produce profound changes in perception, mood, and cognition. These drugs include phenylalkylamines such as mescaline and 2,5-dimethoxy-4-methylamphetamine (DOM), and indoleamines such as (+)-lysergic acid diethylamide (LSD) and psilocybin. Despite their differences in chemical structure, the two classes of hallucinogens produce remarkably similar subjective effects in humans, and induce cross-tolerance. The phenylalkylamine hallucinogens are selective 5-HT(2) receptor agonists, whereas the indoleamines are relatively non-selective for serotonin (5-HT) receptors. There is extensive evidence, from both animal and human studies, that the characteristic effects of hallucinogens are mediated by interactions with the 5-HT(2A) receptor. Nevertheless, there is also evidence that interactions with other receptor sites contribute to the psychopharmacological and behavioral effects of the indoleamine hallucinogens. This article reviews the evidence demonstrating that the effects of indoleamine hallucinogens in a variety of animal behavioral paradigms are mediated by both 5-HT(2) and non-5-HT(2) receptors.
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Affiliation(s)
- Adam L Halberstadt
- Department of Psychiatry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, United States.
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Lauria A, Tutone M, Almerico AM. Virtual lock-and-key approach: the in silico revival of Fischer model by means of molecular descriptors. Eur J Med Chem 2011; 46:4274-80. [PMID: 21775029 DOI: 10.1016/j.ejmech.2011.06.033] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Revised: 06/17/2011] [Accepted: 06/23/2011] [Indexed: 01/09/2023]
Abstract
In the last years the application of computational methodologies in the medicinal chemistry fields has found an amazing development. All the efforts were focused on the searching of new leads featuring a close affinity on a specific biological target. Thus, different molecular modeling approaches in simulation of molecular behavior for a specific biological target were employed. In spite of the increasing reliability of computational methodologies, not always the designed lead, once synthesized and screened, are suitable for the chosen biological target. To give another chance to these compounds, this work tries to resume the old concept of Fischer lock-and-key model. The same can be done for the "re-purposing" of old drugs. In fact, it is known that drugs may have many physiological targets, therefore it may be useful to identify them. This aspect, called "polypharmacology", is known to be therapeutically essential in the different treatments. The proposed protocol, the virtual lock-and-key approach (VLKA), consists in the "virtualization" of biological targets through the respectively known inhibitors. In order to release a real lock it is necessary the key fits the pins of the lock. The molecular descriptors could be considered as pins. A tested compound can be considered a potential inhibitor of a biological target if the values of its molecular descriptors fall in the calculated range values for the set of known inhibitors. The proposed protocol permits to transform a biological target in a "lock model" starting from its known inhibitors. To release a real lock all pins must fit. In the proposed protocol, it was supposed that the higher is the number of fit pins, the higher will be the affinity to the considered biological target. Therefore, each biological target was converted in a sequence of "weighted" molecular descriptor range values (locks) by using the structural features of the known inhibitors. Each biological target lock was tested by performing a molecular descriptors "fitting" on known inhibitors not used in the model construction (keys or test set). The results showed a good predictive capability of the protocol (confidence level 80%). This method gives interesting and convenient results because of the user-defined descriptors and biological targets choice in the process of new inhibitors discovery.
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Affiliation(s)
- Antonino Lauria
- Dipartimento di Scienze e Tecnologie Molecolari e Biomolecolari STEMBIO, Sezione di Chimica Farmaceutica e Biologica, Università di Palermo, Via Archirafi 32, I-90123 Palermo, Italy.
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Marona-Lewicka D, Nichols CD, Nichols DE. An animal model of schizophrenia based on chronic LSD administration: old idea, new results. Neuropharmacology 2011; 61:503-12. [PMID: 21352832 DOI: 10.1016/j.neuropharm.2011.02.006] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Revised: 01/12/2011] [Accepted: 02/02/2011] [Indexed: 11/18/2022]
Abstract
Many people who take LSD experience a second temporal phase of LSD intoxication that is qualitatively different, and was described by Daniel Freedman as "clearly a paranoid state." We have previously shown that the discriminative stimulus effects of LSD in rats also occur in two temporal phases, with initial effects mediated by activation of 5-HT(2A) receptors (LSD30), and the later temporal phase mediated by dopamine D2-like receptors (LSD90). Surprisingly, we have now found that non-competitive NMDA antagonists produced full substitution in LSD90 rats, but only in older animals, whereas in LSD30, or in younger animals, these drugs did not mimic LSD. Chronic administration of low doses of LSD (>3 months, 0.16 mg/kg every other day) induces a behavioral state characterized by hyperactivity and hyperirritability, increased locomotor activity, anhedonia, and impairment in social interaction that persists at the same magnitude for at least three months after cessation of LSD treatment. These behaviors, which closely resemble those associated with psychosis in humans, are not induced by withdrawal from LSD; rather, they are the result of neuroadaptive changes occurring in the brain during the chronic administration of LSD. These persistent behaviors are transiently reversed by haloperidol and olanzapine, but are insensitive to MDL-100907. Gene expression analysis data show that chronic LSD treatment produced significant changes in multiple neurotransmitter system-related genes, including those for serotonin and dopamine. Thus, we propose that chronic treatment of rats with low doses of LSD can serve as a new animal model of psychosis that may mimic the development and progression of schizophrenia, as well as model the established disease better than current acute drug administration models utilizing amphetamine or NMDA antagonists such as PCP.
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MESH Headings
- Akathisia, Drug-Induced/etiology
- Animals
- Antipsychotic Agents/therapeutic use
- Behavior, Animal/drug effects
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- Disease Models, Animal
- Dopamine Agonists/administration & dosage
- Dopamine Agonists/toxicity
- Gene Expression Regulation/drug effects
- Lysergic Acid Diethylamide/administration & dosage
- Lysergic Acid Diethylamide/toxicity
- Male
- Motor Activity/drug effects
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/metabolism
- Psychotic Disorders/drug therapy
- Psychotic Disorders/metabolism
- Psychotic Disorders/physiopathology
- RNA, Messenger/metabolism
- Random Allocation
- Rats
- Rats, Sprague-Dawley
- Receptor, Serotonin, 5-HT2A/chemistry
- Receptor, Serotonin, 5-HT2C/genetics
- Receptor, Serotonin, 5-HT2C/metabolism
- Receptors, Dopamine D2/agonists
- Receptors, Dopamine D2/genetics
- Receptors, Dopamine D2/metabolism
- Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors
- Receptors, Steroid/genetics
- Receptors, Steroid/metabolism
- Receptors, Thyroid Hormone/genetics
- Receptors, Thyroid Hormone/metabolism
- Schizophrenia/drug therapy
- Schizophrenia/metabolism
- Schizophrenia/physiopathology
- Serotonin 5-HT2 Receptor Agonists/administration & dosage
- Serotonin 5-HT2 Receptor Agonists/toxicity
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Affiliation(s)
- Danuta Marona-Lewicka
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, 575 Stadium Mall Dr., Purdue University, West Lafayette, IN 47906-2091, USA
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Pálenícek T, Hlinák Z, Bubeníková-Valesová V, Novák T, Horácek J. Sex differences in the effects of N,N-diethyllysergamide (LSD) on behavioural activity and prepulse inhibition. Prog Neuropsychopharmacol Biol Psychiatry 2010; 34:588-96. [PMID: 20156516 DOI: 10.1016/j.pnpbp.2010.02.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Revised: 02/07/2010] [Accepted: 02/07/2010] [Indexed: 10/19/2022]
Abstract
The aim of this study was to describe sex differences in the behavioural effects of N,N-diethyllysergamide (LSD) (locomotor activity and other behavioural repertoire in the open field) and its effects on sensorimotor gating in rats (prepulse inhibition (PPI) of the acoustic startle reaction). Three groups of animals were analysed: males, oestral and pro-oestral phase females (EP females), and metoestral and dioestral phase females (MD females). LSD (5, 50 and 200 microg/kg subcutaneously) attenuated locomotor activity and normal behavioural repertoire, and induced flat body posture, wet dog shakes and disrupted PPI. The most prominent behavioural findings of LSD were for LSD 200 microg/kg which suppressed almost all behavioural activity. LSD had mainly inhibitory locomotor effects in males and MD females, yet in EP female rats LSD increased locomotion during the second half of testing period. The main sex differences were observed in locomotor and exploratory behaviour. Both EP and MD females were less sensitive to hypolocomotor effects of LSD and had less pronounced thigmotaxis than males. Further EP females had increased rearing after LSD 5microg/kg. On the contrary although LSD disrupted PPI in males and MD female rats, EP females were protected from this disruptive effect. Thus, EP females seem to have a lower sensitivity to LSD behavioural actions.
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Affiliation(s)
- Tomás Pálenícek
- Prague Psychiatric Center, Ustavní 91, 181 03, Prague 8, Czech Republic.
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Keiser MJ, Setola V, Irwin JJ, Laggner C, Abbas AI, Hufeisen SJ, Jensen NH, Kuijer MB, Matos RC, Tran TB, Whaley R, Glennon RA, Hert J, Thomas KLH, Edwards DD, Shoichet BK, Roth BL. Predicting new molecular targets for known drugs. Nature 2009; 462:175-81. [PMID: 19881490 PMCID: PMC2784146 DOI: 10.1038/nature08506] [Citation(s) in RCA: 1124] [Impact Index Per Article: 74.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2009] [Accepted: 09/14/2009] [Indexed: 12/18/2022]
Abstract
Whereas drugs are intended to be selective, at least some bind to several physiologic targets, explaining both side effects and efficacy. As many drug-target combinations exist, it would be useful to explore possible interactions computationally. Here, we compared 3,665 FDA-approved and investigational drugs against hundreds of targets, defining each target by its ligands. Chemical similarities between drugs and ligand sets predicted thousands of unanticipated associations. Thirty were tested experimentally, including the antagonism of the β1 receptor by the transporter inhibitor Prozac, the inhibition of the 5-HT transporter by the ion channel drug Vadilex, and antagonism of the histamine H4 receptor by the enzyme inhibitor Rescriptor. Overall, 23 new drug-target associations were confirmed, five of which were potent (< 100 nM). The physiological relevance of one such, the drug DMT on serotonergic receptors, was confirmed in a knock-out mouse. The chemical similarity approach is systematic and comprehensive, and may suggest side-effects and new indications for many drugs.
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Affiliation(s)
- Michael J Keiser
- Department of Pharmaceutical Chemistry, University of California San Francisco, 1700 4th Street, San Francisco, California 94143-2550, USA
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Marona-Lewicka D, Chemel BR, Nichols DE. Dopamine D4 receptor involvement in the discriminative stimulus effects in rats of LSD, but not the phenethylamine hallucinogen DOI. Psychopharmacology (Berl) 2009; 203:265-77. [PMID: 18604600 DOI: 10.1007/s00213-008-1238-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2008] [Accepted: 06/11/2008] [Indexed: 10/21/2022]
Abstract
RATIONALE Lysergic acid diethylamide (LSD) differs from other types of hallucinogens in that it possesses direct dopaminergic effects. The exact nature of this component has not been elucidated. OBJECTIVE The present study sought to characterize the effects of several dopamine D(4) agonists and antagonists on the discriminative stimulus effect of LSD at two pretreatment times and 2,5-dimethoxy-4-iodoamphetamine (DOI), a selective 5-HT(2A/2C) agonist. MATERIALS AND METHODS Male Sprague-Dawley rats were trained in a two-lever, fixed ratio (FR) 50, food-reinforced task with LSD-30 (0.08 mg/kg, i.p., 30-min pretreatment time), LSD-90 (0.16 mg/kg, i.p., 90-min pretreatment time), and DOI (0.4 mg/kg, i.p., 30-min pretreatment time) as discriminative stimuli. Substitution and combination tests with the dopamine D(4) agonists, ABT-724 and WAY 100635, were performed in all groups. Combination tests were run using the dopamine D(4) antagonists A-381393 and L-745,870 and two antipsychotic drugs, clozapine and olanzapine. RESULTS WAY 100635 produced full substitution in LSD-90 rats, partial substitution in LSD-30 rats, and saline appropriate responding in DOI-trained rats. ABT-724 partially mimicked the LSD-90 and LSD-30 cues, but produced no substitution in DOI-trained rats. In combination tests, both agonists shifted the dose-response curve of LSD leftward, most potently for the LSD-90 cue. The D(4) antagonists significantly attenuated both the LSD-90 and LSD-30 cue, but had no effect on the DOI cue. CONCLUSION Dopamine D(4) receptor activation plays a significant modulatory role in the discriminative stimulus effects in LSD-90-trained rats, most markedly for the later temporal phase of LSD, but has no effect on the cue produced by DOI.
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Affiliation(s)
- Danuta Marona-Lewicka
- Department of Medicinal Chemistry and Molecular Pharmacology, School of Pharmacy and Pharmaceutical Sciences-RHPH, Purdue University, 575 Stadium Mall Dr., West Lafayette, IN 47907-2091, USA
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Winter JC. Hallucinogens as discriminative stimuli in animals: LSD, phenethylamines, and tryptamines. Psychopharmacology (Berl) 2009; 203:251-63. [PMID: 18979087 DOI: 10.1007/s00213-008-1356-8] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Accepted: 09/24/2008] [Indexed: 12/24/2022]
Abstract
BACKGROUND Although man's first encounters with hallucinogens predate written history, it was not until the rise of the sister disciplines of organic chemistry and pharmacology in the nineteenth century that scientific studies became possible. Mescaline was the first to be isolated and its chemical structure determined. Since then, additional drugs have been recovered from their natural sources and synthetic chemists have contributed many more. Given their profound effects upon human behavior and the need for verbal communication to access many of these effects, some see humans as ideal subjects for study of hallucinogens. However, if we are to determine the mechanisms of action of these agents, establish hypotheses testable in human subjects, and explore the mechanistic links between hallucinogens and such apparently disparate topics as idiopathic psychosis, transcendental states, drug abuse, stress disorders, and cognitive dysfunction, studies in animals are essential. Stimulus control by hallucinogens has provided an intuitively attractive approach to the study of these agents in nonverbal species. OBJECTIVE The intent of this review is to provide a brief account of events from the time of the first demonstration of hallucinogen-induced stimulus control to the present. In general, the review is limited to lysergic acid diethylamide (LSD) and the hallucinogenic derivatives of phenethylamine and tryptamine. RESULTS The pharmacological basis for stimulus control by LSD and hallucinogenic phenethylamines and tryptamines is serotonergic in nature. The 5-HT(2A) receptor appears to be the primary site of action with significant modulation by other serotonergic sites including 5-HT(2C) and 5-HT(1A) receptors. Interactions with other neurotransmitters, especially glutamate and dopamine, are under active investigation. Most studies to date have been conducted in the rat but transgenic mice offer interesting possibilities. CONCLUSIONS Hallucinogen-induced stimulus control provides a unique behavioral tool for the prediction of subjective effects in man and for the elucidation of the pharmacological mechanisms of the action of these agents.
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Affiliation(s)
- J C Winter
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, 102 Farber Hall, Buffalo, NY 14214-3000, USA.
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