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T. Páleníček

The Effects of Daytime Psilocybin Administration on Sleep: Implications for Antidepressant Action

February 6, 2022 / Depressive Disorders, Mushrooms / Psilocybin, Papers, Psychology / Leave a Comment / By / , , , , , , , , , , , , , , , ,

Abstract

Serotonergic agonist psilocybin is a psychedelic with antidepressant potential. Sleep may interact with psilocybin’s antidepressant properties like other antidepressant drugs via induction of neuroplasticity. The main aim of the study was to evaluate the effect of psilocybin on sleep architecture on the night after psilocybin administration. Regarding the potential antidepressant properties, we hypothesized that psilocybin, similar to other classical antidepressants, would reduce rapid eye movement (REM) sleep and prolong REM sleep latency. Moreover, we also hypothesized that psilocybin would promote slow-wave activity (SWA) expression in the first sleep cycle, a marker of sleep-related neuroplasticity. Twenty healthy volunteers (10 women, age 28-53) underwent two drug administration sessions, psilocybin or placebo, in a randomized, double-blinded design. Changes in sleep macrostructure, SWA during the first sleep cycle, whole night EEG spectral power across frequencies in non-rapid eye movement (NREM) and REM sleep, and changes in subjective sleep measures were analyzed. The results revealed prolonged REM sleep latency after psilocybin administration and a trend toward a decrease in overall REM sleep duration. No changes in NREM sleep were observed. Psilocybin did not affect EEG power spectra in NREM or REM sleep when examined across the whole night. However, psilocybin suppressed SWA in the first sleep cycle. No evidence was found for sleep-related neuroplasticity, however, a different dosage, timing, effect on homeostatic regulation of sleep, or other mechanisms related to antidepressant effects may play a role. Overall, this study suggests that potential antidepressant properties of psilocybin might be related to changes in sleep.

Dudysová, D., Janků, K., Šmotek, M., Saifutdinova, E., Kopřivová, J., Bušková, J., Mander, B. A., Brunovský, M., Zach, P., Korčák, J., Andrashko, V., Viktorinová, M., Tylš, F., Bravermanová, A., Froese, T., Páleníček, T., & Horáček, J. (2020). The Effects of Daytime Psilocybin Administration on Sleep: Implications for Antidepressant Action. Frontiers in pharmacology, 11, 602590. https://doi.org/10.3389/fphar.2020.602590

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A single inhalation of vapor from dried toad secretion containing 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT) in a naturalistic setting is related to sustained enhancement of satisfaction with life, mindfulness-related capacities, and a decrement of psychopathological symptoms.

April 13, 2019 / Anxiety Disorders / PTSD, Depressive Disorders, DMT, Papers, Psychology, Publications / By / , , , , , ,

Abstract

BACKGROUND:
5-methoxy-N,N-dimethyltryptamine (hereinafter referred to as 5-MeO-DMT) is a psychedelic substance found in the secretion from the parotoid glands of the Bufo alvarius toad. Inhalation of vapor from toad secretion containing 5-MeO-DMT has become popular in naturalistic settings as a treatment of mental health problems or as a means for spiritual exploration. However, knowledge of the effects of 5-MeO-DMT in humans is limited.
AIMS:
The first objective of this study was to assess sub-acute and long-term effects of inhaling vapor from dried toad secretion containing 5-MeO-DMT on affect and cognition. The second objective was to assess whether any changes were associated with the psychedelic experience.
METHODS:
Assessments at baseline, within 24 h and 4 weeks following intake, were made in 42 individuals who inhaled vapor from dried toad secretion at several European locations.
RESULTS:
Relative to baseline, ratings of satisfaction with life and convergent thinking significantly increased right after intake and were maintained at follow-up 4 weeks later. Ratings of mindfulness also increased over time and reached statistical significance at 4 weeks. Ratings of depression, anxiety, and stress decreased after the session, and reached significance at 4 weeks. Participants that experienced high levels of ego dissolution or oceanic boundlessness during the session displayed higher ratings of satisfaction with life and lower ratings of depression and stress.
CONCLUSION:
A single inhalation of vapor from dried toad secretion containing 5-MeO-DMT produces sub-acute and long-term changes in affect and cognition in volunteers. These results warrant exploratory research into therapeutic applications of 5-MeO-DMT.

 
Uthaug, M. V., Lancelotta, R., van Oorsouw, K., Kuypers, K. P. C., Mason, N., Rak, J., … & Páleníček, T. (2019). A single inhalation of vapor from dried toad secretion containing 5-methoxy-N, N-dimethyltryptamine (5-MeO-DMT) in a naturalistic setting is related to sustained enhancement of satisfaction with life, mindfulness-related capacities, and a decrement of psychopathological symptoms. Psychopharmacology, 1-14., https://doi.org/10.1007/s00213-019-05236-w
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A role for enhanced functions of sleep in psychedelic therapy?

April 4, 2018 / Mushrooms / Psilocybin, Papers, Psychology, Publications / By / , ,

Abstract

After a hiatus of several decades, there has been a resurgence of studies into the therapeutic potential of serotonergic psychedelics. When administered in controlled settings, they have been reported to induce a wide variety of long-lasting positive psychological changes. However, the mechanisms by which psychedelics impart these long-lasting benefits remain poorly understood. Here, we highlight one possibility that has remained underexplored: a beneficial interaction with the self-optimizing functions of sleep.
Froese, T., Leenen, I., & Palenicek, T. (2018). A role for enhanced functions of sleep in psychedelic therapy?. Adaptive Behavior, 26(3), 129-135. 10.1177%2F1059712318762735
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Psilocin and ketamine microdosing: effects of subchronic intermittent microdoses in the elevated plus-maze in male Wistar rats

March 13, 2018 / Anxiety Disorders / PTSD, Ketamine, Mushrooms / Psilocybin, Papers, Psychology, Publications / By / , , ,

Abstract

Short-term moderate doses of serotonergic and dissociative hallucinogens can be useful in the treatment of anxiety. Recently, a trend has developed for long-term intermittent ‘microdosing’ (usually one-tenth of a ‘full’ active dose), with reports of long-lasting relief from anxiety and related disorders; however, there is no scientific evidence for the efficacy of therapeutic microdosing nor to show its lasting effects. The objective of this study was to test for lasting effects on anxiety in rats after microdosing with ketamine or psilocin. Over 6 days, Wistar rats (N=40) were administered ketamine (0.5 or 3 mg/kg), psilocin (0.05 or 0.075 mg/kg), or saline on three occasions. A 5-min elevated plus-maze test was conducted 48 h after the final drug treatment (n=8). Dependent variables were entries (frequency), spent time (%), and distance traveled (cm) in each zone, as well as total frequency of rears, stretch-attend postures, and head dips. Statistical analyses of drug effects used separate independent one-way analysis of variance and pair-wise comparisons using independent t-tests. Statistical effects were modest or borderline and were most consistent with a mildly anxiogenic profile, which was significant at lower doses; however, this conclusion remains tentative. The lower doses of ketamine and psilocin produced comparable effects (to one another) across each variable, as did the higher doses. This pattern of effects may suggest a common (e.g. neurotransmitter/receptor) mechanism. We conclude that microdosing with hallucinogens for therapeutic purposes might be counter-productive; however, more research is needed to confirm our findings and to establish their translational relevance to clinical ‘psychedelic’ therapy.
Horsley, R. R., Páleníček, T., Kolin, J., & Valeš, K. (2018). Psilocin and ketamine microdosing: effects of subchronic intermittent microdoses in the elevated plus-maze in male Wistar rats. Behavioural pharmacology. 10.1097/FBP.0000000000000394
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Detailed pharmacological evaluation of methoxetamine (MXE), a novel psychoactive ketamine analogue—Behavioural, pharmacokinetic and metabolic studies in the Wistar rat

May 4, 2016 / Neuroscience, Papers, Publications / By / , , , , ,

Abstract

Methoxetamine (MXE) is a novel psychoactive compound (NPS) that emerged in 2010 as a substitute for the dissociative anaesthetic ketamine. MXE has a reputation of carrying a lower risk of harm than ketamine, however a number of deaths have been reported. Currently very little is known about the psychopharmacological effects of this compound or its toxicity; therefore we tested, in Wistar rats, the effects of MXE in a series of behavioural tasks, measured its pharmacokinetics and urinary metabolites.

Locomotor activity and its spatial characteristics (in the open field) and sensorimotor gating (prepulse inhibition; PPI) were evaluated after 5, 10 and 40 mg/kg subcutaneous (sc.) MXE. Pharmacokinetics and brain: serum ratios were evaluated after 10 mg/kg sc. MXE so that peak drug concentration data could be used to complement interpretation of maximal behavioural effects. Finally, quantification of metabolites in rat urine collected over 24 h was performed after single bolus of MXE 40 mg/kg sc.

5 and 10 mg/kg MXE induced significant locomotor stimulation, in addition it increased thigmotaxis and decreased time spent in the centre of the open field (indicative of anxiogenesis). By contrast, 40 mg/kg reduced locomotion and increased time spent in the centre of the arena, suggesting sedation/anaesthesia or stereotypy. The duration of effects was present for at least 60–90 min, although for 5 mg/kg, locomotion diminished after 60 min. MXE decreased baseline acoustic startle response (ASR) and disrupted PPI, irrespective of testing-onset. MXE (all doses) reduced habituation but only at 60 min. Maximal brain levels of MXE were observed 30 min after administration, remained high at 60 min and progressively declined to around zero after six hours. MXE accumulated in the brain; the brain: serum ratio was between 2.06 and 2.93 throughout the whole observation. The most abundant urinary metabolite was O-desmethylmethoxetamine followed by normethoxetamine.

To conclude, MXE acts behaviourally as a typical dissociative anaesthetic with stimulant and anxiogenic effects at lower doses, sedative/anaesthetic effects at higher doses, and as a disruptor of sensorimotor gating. Its duration of action exceeds that of ketamine which is consistent with reports from MXE users. The accumulation of the drug in brain tissue might reflect MXE’s stronger potency compared to ketamine and indicate increased toxicity.

Horsley, R. R., Lhotkova, E., Hajkova, K., Jurasek, B., Kuchar, M., & Palenicek, T. (2016). Detailed pharmacological evaluation of methoxetamine (MXE), a novel psychoactive ketamine analogue—Behavioural, pharmacokinetic and metabolic studies in the Wistar rat. Brain Research Bulletin. http://dx.doi.org/10.1016/j.brainresbull.2016.05.002
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Sex differences and serotonergic mechanisms in the behavioural effects of psilocin

October 12, 2015 / Mushrooms / Psilocybin, Neuroscience, Papers, Publications / By / , , , , ,

Abstract

Psilocybin has recently attracted a great deal of attention as a clinical research and therapeutic tool. The aim of this paper is to bridge two major knowledge gaps regarding its behavioural pharmacology – sex differences and the underlying receptor mechanisms. We used psilocin (0.25, 1 and 4 mg/kg), an active metabolite of psilocybin, in two behavioural paradigms – the open-field test and prepulse inhibition (PPI) of the acoustic startle reaction. Sex differences were evaluated with respect to the phase of the female cycle. The contribution of serotonin receptors in the behavioural action was tested in male rats with selective serotonin receptor antagonists: 5-HT1A receptor antagonist (WAY100635 1 mg/kg), 5-HT2A receptor antagonist (MDL100907 0.5 mg/kg), 5-HT2B receptor antagonist (SB215505 1 mg/kg) and 5-HT2C receptor antagonist (SB242084 1 mg/kg). Psilocin induced dose-dependent inhibition of locomotion and suppression of normal behaviour in rats (behavioural serotonin syndrome, impaired PPI). The effects were more pronounced in male rats than in females. The inhibition of locomotion was normalized by 5-HT1A and 5-HT2B/C antagonists; however, PPI was not affected significantly by these antagonists. Our findings highlight an important issue of sex-specific reactions to psilocin and that apart from 5-HT2A-mediated effects 5-HT1A and 5-HT2C/B receptors also play an important role. These findings have implications for recent clinical trials.

Tylš, F., Páleníček, T., Kadeřábek, L., Lipski, M., Kubešová, A., & Horáček, J. (2015). Sex differences and serotonergic mechanisms in the behavioural effects of psilocin. Behavioural pharmacology. https://dx.doi.org/10.1097/FBP.0000000000000198

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The effect of psilocin on memory acquisition, retrieval, and consolidation in the rat

May 16, 2014 / Mushrooms / Psilocybin, Neuroscience, Papers, Publications / By / , , ,

Abstract

The involvement of the serotonin system in the pathophysiology of schizophrenia has been elucidated by experiments with hallucinogens. Application of a hallucinogen to humans leads to changes in perception, cognition, emotions, and induction of psychotic-like symptoms that resemble symptoms of schizophrenia. In rodent studies, their acute administration affects sensorimotor gating, locomotor activity, social behavior, and cognition including working memory, the phenotypes are considered as an animal model of schizophrenia. The complexity and singularity of human cognition raises questions about the validity of animal models utilizing agonists of 5-HT2A receptors. The present study thus investigated the effect of psilocin on memory acquisition, reinforced retrieval, and memory consolidation in rats. Psilocin is a main metabolite of psilocybin acting as an agonist at 5-HT2A receptors with a contribution of 5-HT2C and 5-HT1A receptors. First, we tested the effect of psilocin on the acquisition of a Carousel maze, a spatial task requiring navigation using distal cues, attention, and cognitive coordination. Psilocin significantly impaired the acquisition of the Carousel maze at both doses (1 and 4 mg/kg). The higher dose of psilocin blocked the learning processes even in an additional session when the rats received only saline. Next, we examined the effect of psilocin on reinforced retrieval and consolidation in the Morris water maze (MWM). The dose of 4 mg/kg disrupted reinforced retrieval in the MWM. However, the application of a lower dose was without any significant effect. Finally, neither the low nor high dose of psilocin injected post-training caused a deficit in memory consolidation in the MWM. Taken together, the psilocin dose dependently impaired the acquisition of the Carousel maze and reinforced retrieval in MWM; however, it had no effect on memory consolidation.

Rambousek, L., Palenicek, T., Vales, K., & Stuchlik, A. (2014). The effect of psilocin on memory acquisition, retrieval, and consolidation in the rat. Frontiers in Behavioral Neuroscience, 8. https://dx.doi.org/10.3389/fnbeh.2014.00180
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Psilocybin – Summary of knowledge and new perspectives

December 17, 2013 / Anxiety Disorders / PTSD, Depressive Disorders, Headache Pain and Neurological Disorders, Mushrooms / Psilocybin, Neuroscience, Papers, Pharmacology & Chemistry, Psychology, Psychotic Disorders, Publications, Substance Use Disorder / By / , ,

Abstract

Psilocybin, a psychoactive alkaloid contained in hallucinogenic mushrooms, is nowadays given a lot of attention in the scientific community as a research tool for modeling psychosis as well as due to its potential therapeutic effects. However, it is also a very popular and frequently abused natural hallucinogen. This review summarizes all the past and recent knowledge on psilocybin. It briefly deals with its history, discusses the pharmacokinetics and pharmacodynamics, and compares its action in humans and animals. It attempts to describe the mechanism of psychedelic effects and objectify its action using modern imaging and psychometric methods. Finally, it describes its therapeutic and abuse potential.

Tylš, F., Páleníček, T., & Horáček, J. (2014). Psilocybin – Summary of knowledge and new perspectives. European Neuropsychopharmacology, 24, 342-365. http://dx.doi.org/10.1016/j.euroneuro.2013.12.006

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Relationship of ketamine's antidepressant and psychotomimetic effects in unipolar depression

June 25, 2013 / Depressive Disorders, Ketamine, Papers, Psychology, Publications / By / , , , , ,

Abstract

OBJECTIVES:
Ketamine and other NMDA (N-methyl-D-aspartate) antagonists produce fast-acting antidepressant-like effects, although the underlying mechanism is unclear. Furthermore, high affinity NMDA antagonists such as ketamine are associated with psychotomimetic effects. To date the link between the antidepressant and psychotomimetic effects of ketamine has not been explored. We examined the relationship between the antidepressant and psychotomimetic effects of a single ketamine infusion in subjects diagnosed with major depressive disorder.
METHODS:
In a double-blind, cross-over, placebo-controlled, two weeks clinical trial we studied the effects of ketamine (0.54 mg/kg within 30 min) in a group of 27 hospitalized depressive patients.
RESULTS:
Higher intensity of psychotomimetic symptoms, measured using BPRS, during ketamine administration correlated with alleviation in mood ratings during the following week with maximum on day seven. Ketamine was superior to placebo in all visits (day 1, 4, and 7) assessed by MADRS with effect size (Cohen´s d) of 0.62, 0.57, and 0.44 respectively. There was no significant correlation between ketamine and nor-ketamine plasma levels and MADRS score change at any study time point.
CONCLUSION:
The substantial relationship between ketamine’s antidepressant and psychotomimetic effects was found. This relationship could be mediated by the initial steps of ketamine’s action, trough NMDA receptors, shared by both ketamine’s clinical effects.
Sos, P., Klirova, M., Novak, T., Kohutova, B., Horacek, J., & Palenicek, T. (2013). Relationship of ketamine’s antidepressant and psychotomimetic effects in unipolar depression. Neuroendocrinology Letters, 34(4), 287-293.
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