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Neuroscience

Narrative identity, rationality, and microdosing classic psychedelics

May 6, 2019 / LSD, Mushrooms / Psilocybin, Neuroscience, Papers, Psychology, Publications / By / , ,

Abstract

BACKGROUND:

Microdosing involves ingesting a small dose of a classic psychedelic (e.g., LSD and psilocybin) at regular intervals for prolonged periods. The practice is said to reduce anxiety, improve mood, and offer several creative and practical benefits to users. Using the narrative identity theoretical framework, our aim was to explore the experiences of those who microdosed classic psychedelics. Specifically, we sought to understand how and why they began microdosing and how they made sense of their actions in the context of their conventional lives.

METHODS:

To understand the experiences of those who microdose classic psychedelics, we rely on data collected from semi-structured interviews with 30 people who had microdosed.

RESULTS:

Participants saw themselves as conventional citizens who microdosed for rational and instrumental purposes. They emphasized the rationality of microdosing by discussing (1) the practicality of their procurement and administration processes, (2) the connection between their microdosing practice and their general awareness in health and wellness, and (3) the benefits of the practice.

CONCLUSION:

Participants described their microdosing in the context of embracing traditional middle-class values. This created social distance between themselves and those who use drugs recreationally. While people who use drugs recreationally typically construct boundaries by distancing themselves from symbolic others (i.e., “crackheads,” “meth heads,” “junkies”), microdosers constructed boundaries by emphasizing connections to conventional citizens who embrace middle-class values. This connection to conventional citizens allows them to normalize their drug use and facilitates persistence.

Webb, M., Copes, H., & Hendricks, P. S. (2019). Narrative identity, rationality, and microdosing classic psychedelics. International Journal of Drug Policy, 70, 33-39., 10.1016/j.drugpo.2019.04.013
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Pharmacokinetics and subjective effects of a novel oral LSD formulation in healthy subjects.

April 29, 2019 / LSD, Neuroscience, Papers, Pharmacology & Chemistry / By / , , , , ,

Abstract

AIMS:

The aim of the present study was to characterize the pharmacokinetics and exposure-subjective response relationship of a novel oral solution of lysergic acid diethylamide (LSD) that was developed for clinical use in research and patients.

METHOD:

LSD (100 μg) was administered in 27 healthy subjects using a placebo-controlled, double-blind, cross-over design. Plasma levels of LSD, nor-LSD, and 2-oxo-3-hydroxy-LSD (O-H-LSD) and subjective drug effects were assessed up to 11.5 hours.

RESULTS:

First-order elimination kinetics were observed for LSD. Geometric mean maximum concentration (Cmax ) values (range) of 1.7 (1.0-2.9) ng/mL were reached at a tmax (range) of 1.7 (1.0-3.4) hours after drug administration. The plasma half-life (t1/2 ) was 3.6 (2.4-7.3) hours. The AUC∞ was 13 (7.1-28) ng·h/mL. No differences in these pharmacokinetic parameters were found between male and female subjects. Plasma O-H-LSD but not nor-LSD (< 0.01 ng/mL) concentrations could be quantified in all subjects. Geometric mean O-H-LSD Cmax values (range) of 0.11 (0.07-0.19) ng/mL were reached at a tmax (range) of 5 (3.2-8) hours. The t1/2 and AUC∞ values of O-H-LSD were 5.2 (2.6-21) hours and 1.7 (0.85-4.3) ng·h/mL, respectively. The subjective effects of LSD lasted (mean ± SD) for 8.5 ± 2.0 hours (range: 5.3-12.8 h), and peak effects were reached 2.5 ± 0.6 hours (range 1.6-4.3 h) after drug administration. EC50 values were 1.0 ± 0.5 ng/mL and 1.9 ± 1.0 ng/mL for “good” and “bad” subjective drug effects, respectively.

CONCLUSION:

The present study characterized the pharmacokinetics of LSD and its main metabolite O-H-LSD. The subjective effects of LSD were closely associated with changes in plasma concentrations over time.

Holze, F., Duthaler, U., Vizeli, P., Müller, F., Borgwardt, S., & Liechti, M. E. (2019). Pharmacokinetics and subjective effects of a novel oral LSD formulation in healthy subjects. British journal of clinical pharmacology., 10.1111/bcp.13918
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Serotonergic hallucinogens and recognition of facial emotion expressions: a systematic review of the literature.

April 26, 2019 / Anxiety Disorders / PTSD, Depressive Disorders, LSD, Mushrooms / Psilocybin, Neuroscience, Papers, Psychology, Publications / By / , , , , , ,

Abstract

BACKGROUND:
Recognition of emotions in facial expressions (REFE) is a key aspect of social cognition. Anxiety and mood disorders are associated with deficits in REFE, and anxiolytics and antidepressants reverse these deficits. Recent studies have shown that serotonergic hallucinogens (i.e. ayahuasca, dimethyltryptamine, psilocybin, lysergic acid diethylamide [LSD], and mescaline) have anxiolytic and antidepressant properties, but their effects on REFE are not well understood. The purpose of the study was to conduct a systematic review analyzing the effects of serotonergic hallucinogens on REFE in humans.
METHODS:
Studies published in the PubMed, PsycINFO, and Web of Science databases until 19 October 2018 which analyzed the effects of serotonergic hallucinogens on REFE in humans were included.
RESULTS:
Of the 62 studies identified, 8 studies were included. Included studies involved the administration of a single or a few doses of LSD or psilocybin, and most trials were randomized and controlled with placebo. LSD and psilocybin reduced the recognition of negative emotions in most studies and modulated amygdala activity to these stimuli, which was correlated with antidepressive effects in patients. Both drugs were well tolerated.
CONCLUSIONS:
Serotonergic hallucinogens reduced the recognition of negative emotions by modulating amygdala activity. Despite the small sample sizes, results suggest that serotonergic hallucinogens show promising beneficial effects on deficits in REFE.
Rocha, J. M., Osório, F. L., Crippa, J. A. S., Bouso, J. C., Rossi, G. N., Hallak, J. E., & dos Santos, R. G. (2019). Serotonergic hallucinogens and recognition of facial emotion expressions: a systematic review of the literature. Therapeutic advances in psychopharmacology, 9, 2045125319845774., https://doi.org/10.1177/2045125319845774
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Serotonin transporter-ibogaine complexes illuminate mechanisms of inhibition and transport

April 24, 2019 / Anxiety Disorders / PTSD, Iboga / Ibogaine, Neuroscience, Papers, Publications, Substance Use Disorder / By / , , , , ,

Abstract

The serotonin transporter (SERT) regulates neurotransmitter homeostasis through the sodium- and chloride-dependent recycling of serotonin into presynaptic neurons. Major depression and anxiety disorders are treated using selective serotonin reuptake inhibitors-small molecules that competitively block substrate binding and thereby prolong neurotransmitter action. The dopamine and noradrenaline transporters, together with SERT, are members of the neurotransmitter sodium symporter (NSS) family. The transport activities of NSSs can be inhibited or modulated by cocaine and amphetamines, and genetic variants of NSSs are associated with several neuropsychiatric disorders including attention deficit hyperactivity disorder, autism and bipolar disorder. Studies of bacterial NSS homologues-including LeuT-have shown how their transmembrane helices (TMs) undergo conformational changes during the transport cycle, exposing a central binding site to either side of the membrane. However, the conformational changes associated with transport in NSSs remain unknown. To elucidate structure-based mechanisms for transport in SERT we investigated its complexes with ibogaine, a hallucinogenic natural product with psychoactive and anti-addictive properties. Notably, ibogaine is a non-competitive inhibitor of transport but displays competitive binding towards selective serotonin reuptake inhibitors. Here we report cryo-electron microscopy structures of SERT-ibogaine complexes captured in outward-open, occluded and inward-open conformations. Ibogaine binds to the central binding site, and closure of the extracellular gate largely involves movements of TMs 1b and 6a. Opening of the intracellular gate involves a hinge-like movement of TM1a and the partial unwinding of TM5, which together create a permeation pathway that enables substrate and ion diffusion to the cytoplasm. These structures define the structural rearrangements that occur from the outward-open to inward-open conformations, and provide insight into the mechanism of neurotransmitter transport and ibogaine inhibition.

Coleman, J. A., Yang, D., Zhao, Z., Wen, P. C., Yoshioka, C., Tajkhorshid, E., & Gouaux, E. (2019). Serotonin transporter–ibogaine complexes illuminate mechanisms of inhibition and transport. Nature, 569(7754), 141., 10.1038/s41586-019-1135-1
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Cytochrome P450 enzymes contribute to the metabolism of LSD to nor-LSD and 2-oxo-3-hydroxy-LSD: Implications for clinical LSD use

April 11, 2019 / LSD, Neuroscience, Papers, Pharmacology & Chemistry / By / , , , ,

Abstract

In recent years, experimental research on lysergic acid diethylamide (LSD) in humans has gained new momentum. In humans, LSD is metabolized rapidly into several metabolites but knowledge of the involved metabolizing enzymes is limited. The aim of the current study was to identify the cytochrome P450 (CYP) isoforms involved in the metabolism of LSD to 6-norlysergic acid diethylamide (nor-LSD) and 2-oxo-3-hydroxy-LSD (O-H-LSD) in vitro, in order to evaluate potential effects of enzyme polymorphisms or prescription drugs on LSD pharmacokinetics. Additionally, interactions of LSD and both metabolites with 5-hydroxytryptamine (5-HT) receptors were assessed. LSD was incubated with human liver microsomes over 4 h and the production of nor-LSD and O-H-LSD was quantified by liquid chromatography tandem mass spectrometry. Metabolism was inhibited by the addition of specific CYP inhibitors. Additionally, recombinant CYPs were used to verify the inhibition results obtained with microsomes and induction of metabolism was investigated in human hepatocyte-derived cells. Radioligand binding and calcium mobilization assays were used to determine 5-HT receptor affinities and activities, respectively. Human liver microsomes displayed minor metabolite formation (<1% metabolized) over 4 h. CYP2D6, 2E1, and 3A4 significantly contributed to the formation of nor-LSD, and CYP1A2, 2C9, 2E1, and 3A4 were significantly involved in the formation of O-H-LSD. These findings could be verified using recombinant CYPs. Enzyme induction with rifampicin distinctly increased the formation of both metabolites, whereas treatment with omeprazole only slightly increased formation of nor-LSD. LSD and nor-LSD were pharmacologically active at the 5-HT1A, 5-HT2A, 5-HT2B, and 5-HT2C receptors. Nor-LSD mainly differed from the parent compound by having a lower affinity to the 5-HT2C receptor. O-H-LSD displayed substantially weaker affinity and activity at serotonergic receptors in comparison to LSD. To conclude, human liver microsomes converted only small amounts of LSD to nor-LSD and O-H-LSD but several CYPs significantly contributed. Genetic polymorphisms and drug interactions could therefore influence pharmacokinetics and pharmacodynamics of LSD. Nor-LSD likely has hallucinogenic activity similar to LSD, whereas O-H-LSD is inactive. Drug-drug interaction studies in humans are required to further assess the clinical relevance of these findings.

Luethi, D., Hoener, M. C., Krähenbühl, S., Liechti, M. E., & Duthaler, U. (2019). Cytochrome P450 enzymes contribute to the metabolism of LSD to nor-LSD and 2-oxo-3-hydroxy-LSD: Implications for clinical LSD use. Biochemical pharmacology, 164, 129-138., 10.1016/j.bcp.2019.04.013
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Receptor-Enriched Analysis of functional connectivity by targets (REACT): A novel, multimodal analytical approach informed by PET to study the pharmacodynamic response of the brain under MDMA

April 4, 2019 / MDMA, Neuroscience, Papers, Pharmacology & Chemistry / By / , , , , ,

Abstract

One of the main limitations of pharmacological fMRI is its inability to provide a molecular insight into the main effect of compounds, leaving an open question about the relationship between drug effects and haemodynamic response. The aim of this study is to investigate the acute effects of 3,4-methylenedioxymethamphetamine (MDMA) on functional connectivity (FC) using a novel multimodal method (Receptor-Enriched Analysis of functional Connectivity by Targets – REACT). This approach enriches the resting state (rs-)fMRI analysis with the molecular information about the distribution density of serotonin receptors in the brain, given the serotonergic action of MDMA. Twenty healthy subjects participated in this double-blind, placebo-controlled, crossover study. A high-resolution in vivo atlas of four serotonin receptors (5-HT1A, 5-HT1B, 5-HT2A, and 5-HT4) and its transporter (5-HTT) was used as a template in a two-step multivariate regression analysis to estimate the spatial maps reflecting the whole-brain connectivity behaviour related to each target under placebo and MDMA. Results showed that the networks exhibiting significant changes after MDMA administration are the ones informed by the 5-HTT and 5-HT1Adistribution density maps, which are the main targets of this compound. Changes in the 5-HT1A-enriched functional maps were also associated with the pharmacokinetic levels of MDMA and MDMA-induced FC changes in the 5-HT2A-enriched maps correlated with the spiritual experience subscale of the Altered States of Consciousness Questionnaire. By enriching the rs-fMRI analysis with molecular data of voxel-wise distribution of the serotonin receptors across the brain, we showed that MDMA effects on FC can be understood through the distribution of its main targets. This result supports the ability of this method to characterise the specificity of the functional response of the brain to MDMA binding to serotonergic receptors, paving the way to the definition of a new fingerprint in the characterization of new compounds and potentially to a further understanding to the response to treatment.

Dipasquale, O., Selvaggi, P., Veronese, M., Gabay, A. S., Turkheimer, F., & Mehta, M. A. (2019). Receptor-Enriched Analysis of functional connectivity by targets (REACT): A novel, multimodal analytical approach informed by PET to study the pharmacodynamic response of the brain under MDMA. NeuroImage, 195, 252-260., 10.1016/j.neuroimage.2019.04.007

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Oxytocin-dependent reopening of a social reward learning critical period with MDMA

April 3, 2019 / Depressive Disorders, MDMA, Neuroscience, Papers, Publications / By / , , , , , ,

Abstract

A critical period is a developmental epoch during which the nervous system is expressly sensitive to specific environmental stimuli that are required for proper circuit organization and learning. Mechanistic characterization of critical periods has revealed an important role for exuberant brain plasticity during early development, and for constraints that are imposed on these mechanisms as the brain matures. In disease states, closure of critical periods limits the ability of the brain to adapt even when optimal conditions are restored. Thus, identification of manipulations that reopen critical periods has been a priority for translational neuroscience. Here we provide evidence that developmental regulation of oxytocin-mediated synaptic plasticity (long-term depression) in the nucleus accumbens establishes a critical period for social reward learning. Furthermore, we show that a single dose of (+/-)-3,4-methylendioxymethamphetamine (MDMA) reopens the critical period for social reward learning and leads to a metaplastic upregulation of oxytocin-dependent long-term depression. MDMA-induced reopening of this critical period requires activation of oxytocin receptors in the nucleus accumbens, and is recapitulated by stimulation of oxytocin terminals in the nucleus accumbens. These findings have important implications for understanding the pathogenesis of neurodevelopmental diseases that are characterized by social impairments and of disorders that respond to social influence or are the result of social injury.

Nardou, R., Lewis, E. M., Rothhaas, R., Xu, R., Yang, A., Boyden, E., & Dölen, G. (2019). Oxytocin-dependent reopening of a social reward learning critical period with MDMA. Nature, 569(7754), 116., 10.1038/s41586-019-1075-9
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Sensitization to the prosocial effects of 3,4-methylenedioxymethamphetamine (MDMA).

March 25, 2019 / Anxiety Disorders / PTSD, MDMA, Neuroscience, Papers, Psychology, Publications / By / , , , , ,

Abstract

The recreational drug 3,4-methylenedioxymethamphetamine (MDMA) has well documented prosocial effects and is currently under clinical investigation as a treatment for patients with PTSD, autism, and other conditions. Early clinical trials have found that MDMA-assisted therapy may have robust long-lasting therapeutic effects, yet the mechanism by which acute treatments produce these long-term effects is unclear. Sensitization to certain behavioral drug effects is a common rodent model used to assess long-lasting neurobiological adaptations induced by acute drug treatments. Nine independent experiments were undertaken to investigate if and how mice sensitize to the prosocial effects of MDMA. When treated with 7.8 mg/kg MDMA and paired every other day for a week, MDMA-induced social interaction increased precipitously across treatment sessions. This previously unreported phenomenon was investigated and found to be heavily influenced by a social context and 5-HT2AR activation. Social sensitization did not appear to develop if mice were administered MDMA in isolation, and pretreatment with MDL100907, a selective 5-HT2AR antagonist, inhibited the development of social sensitization. However, when MDL100907 was administered to mice that had already been sensitized, it did not attenuate social interaction, suggesting that 5-HT2AR activity may be necessary for the development of social sensitization but not the expression of MDMA-induced social behavior. Additional investigation is warranted to further explore the phenomenon of social sensitization and to determine the underlying neurobiological mechanisms.
Curry, D. W., Berro, L. F., Belkoff, A. R., Sulima, A., Rice, K. C., & Howell, L. L. (2019). Sensitization to the prosocial effects of 3, 4-methylenedioxymethamphetamine (MDMA). Neuropharmacology, 151, 13-20., https://doi.org/10.1016/j.neuropharm.2019.03.017
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Salvia divinorum: from recreational hallucinogenic use to analgesic and anti-inflammatory action

March 22, 2019 / Biology & Ethnobotany, Neuroscience, Papers, Pharmacology & Chemistry, Psychiatry & Medicine, Publications, Salvia / Salvinorin A / By / ,

Abstract

Salvia divinorum is a herbal plant native to the southwest region of Mexico. Traditional preparations of this plant have been used in illness treatments that converge with inflammatory conditions and pain. Currently, S. divinorum extracts have become popular in several countries as a recreational drug due to its hallucinogenic effects. Its main active component is a diterpene named salvinorin A (SA), a potent naturally occurring hallucinogen with a great affinity to the κ opioid receptors and with allosteric modulation of cannabinoid type 1 receptors. Recent biochemical research has revealed the mechanism of action of the anti-inflammatory and analgesic effect of SA at the cellular and molecular level. Nevertheless, because of their short-lasting and hallucinogenic effect, the research has focused on discovering a new analogue of SA that is able to induce analgesia and reduce inflammation with a long-lasting effect but without the hallucinatory component. In this review, we explore the role of S. divinorum, SA and its analogues. We focus mainly on their analgesic and anti-inflammatory roles but also mention their psychoactive properties.

Coffeen, U., & Pellicer, F. (2019). Salvia divinorum: from recreational hallucinogenic use to analgesic and anti-inflammatory action. Journal of pain research, 12, 1069., 10.2147/JPR.S188619

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Ibogaine Administration Modifies GDNF and BDNF Expression in Brain Regions Involved in Mesocorticolimbic and Nigral Dopaminergic Circuits.

March 5, 2019 / Iboga / Ibogaine, Neuroscience, Papers, Psychology, Publications, Substance Use Disorder / By / , , , , , ,

Abstract

Ibogaine is an atypical psychedelic alkaloid, which has been subject of research due to its reported ability to attenuate drug-seeking behavior. Recent work has suggested that ibogaine effects on alcohol self-administration in rats are related to the release of Glial cell Derived Neurotrophic Factor (GDNF) in the Ventral Tegmental Area (VTA), a mesencephalic region which hosts the soma of dopaminergic neurons. Although previous reports have shown ibogaine’s ability to induce GDNF expression in rat midbrain, there are no studies addressing its effect on the expression of GDNF and other neurotrophic factors (NFs) such as Brain Derived Neurotrophic Factor (BDNF) or Nerve Growth Factor (NGF) in distinct brain regions containing dopaminergic neurons. In this work, we examined the effect of ibogaine acute administration on the expression of these NFs in the VTA, Prefrontal Cortex (PFC), Nucleus Accumbens (NAcc) and the Substantia Nigra (SN). Rats were i.p. treated with ibogaine 20 mg/kg (I20), 40 mg/kg (I40) or vehicle, and NFs expression was analyzed after 3 and 24 h. At 24 h an increase of the expression of the NFs transcripts was observed in a site and dose dependent manner. Only for I40, GDNF was selectively upregulated in the VTA and SN. Both doses elicited a large increase in the expression of BDNF transcripts in the NAcc, SN and PFC, while in the VTA a significant effect was found only for I40. Finally, NGF mRNA was upregulated in all regions after I40, while I20 showed a selective upregulation in PFC and VTA. Regarding protein levels, an increase of GDNF was observed in the VTA only for I40 but no significant increase for BDNF was found in all the studied areas. Interestingly, an increase of proBDNF was detected in the NAcc for both doses. These results show for the first time a selective increase of GDNF specifically in the VTA for I40 but not for I20 after 24 h of administration, which agrees with the effective dose found in previous self-administration studies in rodents. Further research is needed to understand the contribution of these changes to ibogaine’s ability to attenuate drug-seeking behavior.
Marton, S., González, B., Rodríguez, S., Miquel, E., Martínez-Palma, L., Pazos, M., … & Scorza, C. (2019). Ibogaine administration modifies GDNF and BDNF expression in brain regions involved in mesocorticolimbic and nigral dopaminergic circuits. Frontiers in pharmacology, 10, 193., https://doi.org/10.3389/fphar.2019.00193
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