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Ivan VE, Tomàs-Cuesta DP, Esteves IM, Curic D, Mohajerani M, McNaughton BL, Davidsen J, Gruber AJ. The Nonclassic Psychedelic Ibogaine Disrupts Cognitive Maps. BIOLOGICAL PSYCHIATRY GLOBAL OPEN SCIENCE 2024; 4:275-283. [PMID: 38298796 PMCID: PMC10829624 DOI: 10.1016/j.bpsgos.2023.07.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 07/20/2023] [Accepted: 07/23/2023] [Indexed: 02/02/2024] Open
Abstract
Background The ability of psychedelic compounds to profoundly alter mental function has been long known, but the underlying changes in cellular-level information encoding remain poorly understood. Methods We used two-photon microscopy to record from the retrosplenial cortex in head-fixed mice running on a treadmill before and after injection of the nonclassic psychedelic ibogaine (40 mg/kg intraperitoneally). Results We found that the cognitive map, formed by the representation of position encoded by ensembles of individual neurons in the retrosplenial cortex, was destabilized by ibogaine when mice had to infer position between tactile landmarks. This corresponded with increased neural activity rates, loss of correlation structure, and increased responses to cues. Ibogaine had surprisingly little effect on the size-frequency distribution of network activity events, suggesting that signal propagation within the retrosplenial cortex was largely unaffected. Conclusions Taken together, these data support proposals that compounds with psychedelic properties disrupt representations that are important for constraining neocortical activity, thereby increasing the entropy of neural signaling. Furthermore, the loss of expected position encoding between landmarks recapitulated effects of hippocampal impairment, suggesting that disruption of cognitive maps or other hippocampal processing may be a contributing mechanism of discoordinated neocortical activity in psychedelic states.
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Affiliation(s)
- Victorita E. Ivan
- Canadian Center for Behavioural Neuroscience, Department of Neuroscience, University of Lethbridge, Lethbridge, Alberta, Canada
| | - David P. Tomàs-Cuesta
- Canadian Center for Behavioural Neuroscience, Department of Neuroscience, University of Lethbridge, Lethbridge, Alberta, Canada
| | - Ingrid M. Esteves
- Canadian Center for Behavioural Neuroscience, Department of Neuroscience, University of Lethbridge, Lethbridge, Alberta, Canada
| | - Davor Curic
- Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada
| | - Majid Mohajerani
- Canadian Center for Behavioural Neuroscience, Department of Neuroscience, University of Lethbridge, Lethbridge, Alberta, Canada
| | - Bruce L. McNaughton
- Canadian Center for Behavioural Neuroscience, Department of Neuroscience, University of Lethbridge, Lethbridge, Alberta, Canada
- Center for the Neurobiology of Learning and Memory, University of California Irvine, Irvine, California
| | - Joern Davidsen
- Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada
| | - Aaron J. Gruber
- Canadian Center for Behavioural Neuroscience, Department of Neuroscience, University of Lethbridge, Lethbridge, Alberta, Canada
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González-Trujano ME, Krengel F, Reyes-Chilpa R, Villasana-Salazar B, González-Gómez JD, Santos-Valencia F, Urbina-Trejo E, Martínez A, Martínez-Vargas D. Tabernaemontana arborea and ibogaine induce paroxysmal EEG activity in freely moving mice: involvement of serotonin 5-HT 1A receptors. Neurotoxicology 2022; 89:79-91. [PMID: 34999156 DOI: 10.1016/j.neuro.2022.01.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 12/08/2021] [Accepted: 01/04/2022] [Indexed: 02/07/2023]
Abstract
Several Apocynaceae species, most notably Tabernanthe iboga, Voacanga africana and many Tabernaemontana species, produce ibogan-type alkaloids. Although a large amount of information exists about the Tabernaemontana genus, knowledge concerning chemistry and biological activity remains lacking for several species, especially related to their effects on the central nervous system (CNS). The aim of this study was to evaluate the effect of Tabernaemontana arborea Rose ex J.D.Sm. (T. arborea) hydroalcoholic extract (30, 56.2 and 100 mg/kg, i.p.) and two of its main alkaloids (ibogaine and voacangine, 30 mg/kg, i.p.) on electroencephalographic (EEG) activity alone and in the presence of the chemical convulsant agent pentylenetetrazole (PTZ, 85 mg/kg, i.p.) in mice. EEG spectral power analysis showed that T. arborea extract (56.2 and 100 mg/kg) and ibogaine (30 mg/kg, i.p.) promoted a significant increase in the relative power of the delta band and a significant reduction in alpha band values, denoting a CNS depressant effect. Voacangine (30 mg/kg, i.p.) provoked an EEG flattening pattern. The PTZ-induced seizures were not modified in the presence of T. arborea, ibogaine, or voacangine. However, sudden death was observed in mice treated with T. arborea extract at 100 mg/kg, i.p., combined with PTZ. Because T. arborea extract (100 mg/kg, i.p.) and ibogaine (30 mg/kg, i.p.), but not voacangine (30 mg/kg, i.p.), induced paroxysmal activity in the EEG, both were explored in the presence of a serotonin 5-HT1A receptor antagonist (WAY100635, 1 mg/kg, i.p.). The antagonist abolished the paroxysmal activity provoked by T. arborea (100 mg/kg, i.p.) but not that observed with ibogaine, corroborating the participation of serotonin neurotransmission in the T. arborea effects. In conclusion, high doses of the T. arborea extract induced abnormal EEG activity due in part to the presence of ibogaine and involving serotonin 5-HT1A receptor participation. Nevertheless, other possible constituents and mechanisms might participate in this complex excitatory activity that would be interesting to explore in future studies.
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Affiliation(s)
- María Eva González-Trujano
- Laboratorio de Neurofarmacología de Productos Naturales, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría "Ramón de la Fuente Muñiz", Calz. México-Xochimilco 101, Col. San Lorenzo Huipulco, 14370, Ciudad de México, Mexico.
| | - Felix Krengel
- Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de México, Av. Universidad 3000, C.P. 04360, Ciudad Universitaria, Ciudad de México, Mexico; Instituto de Química, Universidad Nacional Autónoma de México. Circuito exterior s/n, Ciudad Universitaria, Ciudad de México, Mexico.
| | - Ricardo Reyes-Chilpa
- Instituto de Química, Universidad Nacional Autónoma de México. Circuito exterior s/n, Ciudad Universitaria, Ciudad de México, Mexico.
| | - Benjamín Villasana-Salazar
- Laboratorio de Neurofisiología del Control y la Regulación, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría "Ramón de la Fuente Muñiz", Calz. México-Xochimilco 101, Col. San Lorenzo Huipulco, 14370, Ciudad de México, Mexico.
| | - José David González-Gómez
- Laboratorio de Neurofisiología del Control y la Regulación, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría "Ramón de la Fuente Muñiz", Calz. México-Xochimilco 101, Col. San Lorenzo Huipulco, 14370, Ciudad de México, Mexico.
| | - Fernando Santos-Valencia
- Laboratorio de Neurofisiología del Control y la Regulación, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría "Ramón de la Fuente Muñiz", Calz. México-Xochimilco 101, Col. San Lorenzo Huipulco, 14370, Ciudad de México, Mexico.
| | - Edgar Urbina-Trejo
- Laboratorio de Neurofisiología del Control y la Regulación, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría "Ramón de la Fuente Muñiz", Calz. México-Xochimilco 101, Col. San Lorenzo Huipulco, 14370, Ciudad de México, Mexico.
| | - Adrián Martínez
- Laboratorio de Sueño y Epilepsia, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría "Ramón de la Fuente Muñiz", Calz. México-Xochimilco 101, Col. San Lorenzo Huipulco, 14370, Ciudad de México, Mexico.
| | - David Martínez-Vargas
- Laboratorio de Neurofisiología del Control y la Regulación, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría "Ramón de la Fuente Muñiz", Calz. México-Xochimilco 101, Col. San Lorenzo Huipulco, 14370, Ciudad de México, Mexico.
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3
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Iyer RN, Favela D, Zhang G, Olson DE. The iboga enigma: the chemistry and neuropharmacology of iboga alkaloids and related analogs. Nat Prod Rep 2021; 38:307-329. [PMID: 32794540 DOI: 10.1039/d0np00033g] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Covering: 2000 up to 2020 Few classes of natural products have inspired as many chemists and biologists as have the iboga alkaloids. This family of monoterpenoid indole alkaloids includes the anti-addictive compound ibogaine as well as catharanthine, a precursor to the chemotherapeutic vinblastine. Despite being known for over 120 years, these small molecules continue to challenge our assumptions about biosynthetic pathways, catalyze our creativity for constructing complex architectures, and embolden new approaches for treating mental illness. This review will cover recent advances in both the biosynthesis and chemical synthesis of iboga alkaloids as well as their use as next-generation neurotherapeutics. Whenever appropriate, we provide historical context for the discoveries of the past decade and indicate areas that have yet to be resolved. While significant progress regarding their chemistry and pharmacology has been made since the 1960s, it is clear that the iboga alkaloids will continue to stoke scientific innovation for years to come.
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Affiliation(s)
- Rishab N Iyer
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA.
| | - David Favela
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA.
| | - Guoliang Zhang
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA.
| | - David E Olson
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA. and Department of Biochemistry & Molecular Medicine, School of Medicine, University of California, Davis, 2700 Stockton Blvd, Suite 2102, Sacramento, CA 95817, USA and Center for Neuroscience, University of California, Davis, 1544 Newton Ct, Davis, CA 95618, USA
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Gassaway MM, Jacques TL, Kruegel AC, Karpowicz RJ, Li X, Li S, Myer Y, Sames D. Deconstructing the Iboga Alkaloid Skeleton: Potentiation of FGF2-induced Glial Cell Line-Derived Neurotrophic Factor Release by a Novel Compound. ACS Chem Biol 2016; 11:77-87. [PMID: 26517751 DOI: 10.1021/acschembio.5b00678] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Modulation of growth factor signaling pathways in the brain represents a new experimental approach to treating neuropsychiatric disorders such as depression, anxiety, and addiction. Neurotrophins and growth factors exert synaptic, neuronal, and circuit level effects on a wide temporal range, which suggests a possibility of rapid and lasting therapeutic effects. Consequently, identification of small molecules that can either enhance the release of growth factors or potentiate their respective pathways will provide a drug-like alternative to direct neurotrophin administration or viral gene delivery and thus represents an important frontier in chemical biology and drug design. Glial cell line-derived neurotrophic factor (GDNF), in particular, has been implicated in marked reduction of alcohol consumption in rodent addiction models, and the natural product ibogaine, a substance used traditionally in ritualistic ceremonies, has been suggested to increase the synthesis and release of GDNF in the dopaminergic system in rats. In this report, we describe a novel iboga analog, XL-008, created by unraveling the medium size ring of the ibogamine skeleton, and its ability to induce release of GDNF in C6 glioma cells. Additionally, XL-008 potentiates the release of GDNF induced by fibroblast growth factor 2 (FGF2), another neurotrophin implicated in major depressive disorder, increasing potency more than 2-fold (from 7.85 ± 2.59 ng/mL to 3.31 ± 0.98 ng/mL) and efficacy more than 3-fold. The GDNF release by both XL-008 and the FGF2/XL-008 mixture was found to be mediated through the MEK and PI3K signaling pathways but not through PLCγ in C6 glioma cells.
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Affiliation(s)
- Madalee M. Gassaway
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Teresa L. Jacques
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Andrew C. Kruegel
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Richard J. Karpowicz
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Xiaoguang Li
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Shu Li
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Yves Myer
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Dalibor Sames
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
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Antonio T, Childers SR, Rothman RB, Dersch CM, King C, Kuehne M, Bornmann WG, Eshleman AJ, Janowsky A, Simon ER, Reith MEA, Alper K. Effect of Iboga alkaloids on µ-opioid receptor-coupled G protein activation. PLoS One 2013; 8:e77262. [PMID: 24204784 PMCID: PMC3818563 DOI: 10.1371/journal.pone.0077262] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Accepted: 08/31/2013] [Indexed: 01/13/2023] Open
Abstract
OBJECTIVE The iboga alkaloids are a class of small molecules defined structurally on the basis of a common ibogamine skeleton, some of which modify opioid withdrawal and drug self-administration in humans and preclinical models. These compounds may represent an innovative approach to neurobiological investigation and development of addiction pharmacotherapy. In particular, the use of the prototypic iboga alkaloid ibogaine for opioid detoxification in humans raises the question of whether its effect is mediated by an opioid agonist action, or if it represents alternative and possibly novel mechanism of action. The aim of this study was to independently replicate and extend evidence regarding the activation of μ-opioid receptor (MOR)-related G proteins by iboga alkaloids. METHODS Ibogaine, its major metabolite noribogaine, and 18-methoxycoronaridine (18-MC), a synthetic congener, were evaluated by agonist-stimulated guanosine-5´-O-(γ-thio)-triphosphate ([(35)S]GTPγS) binding in cells overexpressing the recombinant MOR, in rat thalamic membranes, and autoradiography in rat brain slices. RESULTS AND SIGNIFICANCE In rat thalamic membranes ibogaine, noribogaine and 18-MC were MOR antagonists with functional Ke values ranging from 3 uM (ibogaine) to 13 uM (noribogaine and 18MC). Noribogaine and 18-MC did not stimulate [(35)S]GTPγS binding in Chinese hamster ovary cells expressing human or rat MORs, and had only limited partial agonist effects in human embryonic kidney cells expressing mouse MORs. Ibogaine did not did not stimulate [(35)S]GTPγS binding in any MOR expressing cells. Noribogaine did not stimulate [(35)S]GTPγS binding in brain slices using autoradiography. An MOR agonist action does not appear to account for the effect of these iboga alkaloids on opioid withdrawal. Taken together with existing evidence that their mechanism of action also differs from that of other non-opioids with clinical effects on opioid tolerance and withdrawal, these findings suggest a novel mechanism of action, and further justify the search for alternative targets of iboga alkaloids.
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MESH Headings
- Animals
- Autoradiography
- Bridged-Ring Compounds/pharmacology
- CHO Cells
- Cricetulus
- Dose-Response Relationship, Drug
- Female
- Gene Expression
- Guanosine 5'-O-(3-Thiotriphosphate)/pharmacology
- HEK293 Cells
- Humans
- Ibogaine/analogs & derivatives
- Ibogaine/pharmacology
- Organ Specificity
- Rats
- Rats, Sprague-Dawley
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/antagonists & inhibitors
- Receptors, Opioid, mu/genetics
- Receptors, Opioid, mu/metabolism
- Substance Withdrawal Syndrome/prevention & control
- Thalamus/drug effects
- Thalamus/metabolism
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Affiliation(s)
- Tamara Antonio
- Department of Psychiatry, New York University School of Medicine, New York, New York, United States of America
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, New York, United States of America
| | - Steven R. Childers
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, North Carolina, United States of America
| | - Richard B. Rothman
- Translational Pharmacology Research Section, National Institute on Drug Abuse Intramural Research Program, Baltimore, Maryland, United States of America
| | - Christina M. Dersch
- Translational Pharmacology Research Section, National Institute on Drug Abuse Intramural Research Program, Baltimore, Maryland, United States of America
| | - Christine King
- Department of Psychiatry, New York University School of Medicine, New York, New York, United States of America
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, New York, United States of America
| | - Martin Kuehne
- Department of Chemistry, University of Vermont, Burlington, Vermont, United States of America
| | - William G. Bornmann
- Department of Experimental Therapeutics, University of Texas M. D. Anderson Cancer Center, Houston, Texas, United States of America
| | - Amy J. Eshleman
- Research Service, VA Medical Center, and Departments of Psychiatry and Behavioral Neuroscience, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Aaron Janowsky
- Research Service, VA Medical Center, and Departments of Psychiatry and Behavioral Neuroscience, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Eric R. Simon
- Department of Psychiatry, New York University School of Medicine, New York, New York, United States of America
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, New York, United States of America
| | - Maarten E. A. Reith
- Department of Psychiatry, New York University School of Medicine, New York, New York, United States of America
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, New York, United States of America
| | - Kenneth Alper
- Department of Psychiatry, New York University School of Medicine, New York, New York, United States of America
- Department of Neurology, New York University School of Medicine, New York, New York, United States of America
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6
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Rodger J. The visionary cure of the addiction war? Ibogaine: social context, subcultural identity, and implications for drug policy. DRUGS AND ALCOHOL TODAY 2011. [DOI: 10.1108/17459261111174037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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7
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Jain R, Mukherjee K, Balhara YPS. The role of NMDA receptor antagonists in nicotine tolerance, sensitization, and physical dependence: a preclinical review. Yonsei Med J 2008; 49:175-88. [PMID: 18452252 PMCID: PMC2615322 DOI: 10.3349/ymj.2008.49.2.175] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2007] [Accepted: 05/30/2007] [Indexed: 12/04/2022] Open
Abstract
Nicotine, the primary psychoactive component of tobacco products, produces diverse neurophysiological, motivational, and behavioral effects through several brain regions and neurochemical pathways. Various neurotransmitter systems have been explored to understand the mechanisms behind nicotine tolerance, dependence, and withdrawal. Recent evidence suggests that glutamate neurotransmission has an important role in this phenomenon. The aim of the present review is to discuss preclinical findings concerning the role of N-methyl-D-aspartate (NMDA) receptor neurotransmission in mediating the behavioral effects of nicotine, tolerance, sensitization, dependence, and withdrawal. Based on preclinical findings, it is hypothesized that NMDA receptors mediate the common adaptive processes that are involved in the development, maintenance, and expression of nicotine addiction. Modulation of glutamatergic neurotransmission with NMDA receptor antagonists may prove to be useful in alleviating the symptoms of nicotine abstinence and facilitate tobacco-smoking cessation.
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Affiliation(s)
- Raka Jain
- National Drug Dependence Treatment Centre and Department of Psychiatry, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, Pin 110029, India.
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8
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Alper KR, Lotsof HS, Kaplan CD. The ibogaine medical subculture. JOURNAL OF ETHNOPHARMACOLOGY 2008; 115:9-24. [PMID: 18029124 DOI: 10.1016/j.jep.2007.08.034] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2007] [Revised: 08/21/2007] [Accepted: 08/21/2007] [Indexed: 05/25/2023]
Abstract
AIM OF THE STUDY Ibogaine is a naturally occurring psychoactive indole alkaloid that is used to treat substance-related disorders in a global medical subculture, and is of interest as an ethnopharmacological prototype for experimental investigation and possible rational pharmaceutical development. The subculture is also significant for risks due to the lack of clinical and pharmaceutical standards. This study describes the ibogaine medical subculture and presents quantitative data regarding treatment and the purpose for which individuals have taken ibogaine. MATERIALS AND METHODS All identified ibogaine "scenes" (defined as a provider in an associated setting) apart from the Bwiti religion in Africa were studied with intensive interviewing, review of the grey literature including the Internet, and the systematic collection of quantitative data. RESULTS Analysis of ethnographic data yielded a typology of ibogaine scenes, "medical model", "lay provider/treatment guide", "activist/self-help", and "religious/spiritual". An estimated 3414 individuals had taken ibogaine as of February 2006, a fourfold increase relative to 5 years earlier, with 68% of the total having taken it for the treatment of a substance-related disorder, and 53% specifically for opioid withdrawal. CONCLUSIONS Opioid withdrawal is the most common reason for which individuals took ibogaine. The focus on opioid withdrawal in the ibogaine subculture distinguishes ibogaine from other agents commonly termed "psychedelics", and is consistent with experimental research and case series evidence indicating a significant pharmacologically mediated effect of ibogaine in opioid withdrawal.
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Affiliation(s)
- Kenneth R Alper
- Department of Psychiatry, New York University School of Medicine, New York, NY 10016, USA.
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9
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Levant B, Pazdernik TL. Differential effects of ibogaine on local cerebral glucose utilization in drug-naive and morphine-dependent rats. Brain Res 2004; 1003:159-67. [PMID: 15019575 DOI: 10.1016/j.brainres.2003.12.032] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/22/2003] [Indexed: 11/24/2022]
Abstract
Ibogaine, a hallucinogenic indole alkaloid, has been proposed as a treatment for addiction to opioids and other drugs of abuse. The mechanism for its putative anti-addictive effects is unknown. In this study, the effects of ibogaine on local cerebral glucose utilization (LCGU) were determined in freely moving, drug-naive, or morphine-dependent adult, male, Sprague-Dawley rats using the [(14)C]2-deoxyglucose (2-DG) method. Morphine-dependent rats were treated with increasing doses of morphine (5-25 mg/kg, s.c., b.i.d.) and then maintained at 25 mg/kg (b.i.d.) for 4-7 days. For the 2-DG procedure, rats were injected with saline or ibogaine (40 mg/kg, i.p.). 2-DG was administered 1 h after administration of ibogaine. The rate of LCGU was determined by quantitative autoradiography in 46 brain regions. In drug-naive animals, ibogaine produced significant increases in LCGU in the parietal, cingulate, and occipital cortices and cerebellum compared to controls consistent with its activity as a hallucinogen and a tremorogen. Morphine-dependent rats had only minor alterations in LCGU at the time assessed in this experiment. However, in morphine-dependent animals, ibogaine produced a global decrease in LCGU that was greatest in brain regions such as the lateral and medial preoptic areas, nucleus of the diagonal band, nucleus accumbens shell, inferior colliculus, locus coeruleus, and flocculus compared to morphine-dependent animals treated with saline. These findings indicate that ibogaine produces distinctly different effects on LCGU in drug-naive and morphine-dependent rats. This suggests that different mechanisms may underlie ibogaine's hallucinogenic and anti-addictive effects.
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Affiliation(s)
- Beth Levant
- Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, Kansas City, KS 66160-7417, USA.
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