Effects Of Psilocybin Research Articles

Molecular Mechanisms of Psilocybin and Implications for the Treatment of Depression.

Therapeutic deficiencies with monoaminergic antidepressants invites the need to identify and develop novel rapid-acting antidepressants. Hitherto, ketamine and esketamine are identified as safe, well-tolerated rapid-acting antidepressants in adults with treatment-resistant depression, and also mitigate measures of suicidality. Psilocybin is a naturally occurring psychoactive alkaloid and non-selective agonist at many serotonin receptors, especially at serotonin 5-HT2A receptors, and is found in the Psilocybe genus of mushrooms. Preliminary studies with psilocybin have shown therapeutic promise across diverse populations including major depressive disorder. The pharmacodynamic mechanisms mediating the antidepressant and psychedelic effects of psilocybin are currently unknown but are thought to involve the modulation of the serotonergic system, primarily through agonism at the 5-HT2A receptors and downstream changes in gene expression. It is also established that indirect effects on dopaminergic and glutamatergic systems are contributory, as well as effects at other lower affinity targets. Along with the direct effects on neurochemical systems, psilocybin alters neural circuitry and key brain regions previously implicated in depression, including the default mode network and amygdala. The aim of this review is to synthesize the current understanding of the receptor pharmacology and neuronal mechanisms underlying the psychedelic and putative antidepressant properties of psilocybin.

Psilocybin therapy increases cognitive and neural flexibility in patients with major depressive disorder

Psilocybin has shown promise for the treatment of mood disorders, which are often accompanied by cognitive dysfunction including cognitive rigidity. Recent studies have proposed neuropsychoplastogenic effects as mechanisms underlying the enduring therapeutic effects of psilocybin. In an open-label study of 24 patients with major depressive disorder, we tested the enduring effects of psilocybin therapy on cognitive flexibility (perseverative errors on a set-shifting task), neural flexibility (dynamics of functional connectivity or dFC via functional magnetic resonance imaging), and neurometabolite concentrations (via magnetic resonance spectroscopy) in brain regions supporting cognitive flexibility and implicated in acute psilocybin effects (e.g., the anterior cingulate cortex, or ACC). Psilocybin therapy increased cognitive flexibility for at least 4 weeks post-treatment, though these improvements were not correlated with the previously reported antidepressant effects. One week after psilocybin therapy, glutamate and N-acetylaspartate concentrations were decreased in the ACC, and dFC was increased between the ACC and the posterior cingulate cortex (PCC). Surprisingly, greater increases in dFC between the ACC and PCC were associated with less improvement in cognitive flexibility after psilocybin therapy. Connectome-based predictive modeling demonstrated that baseline dFC emanating from the ACC predicted improvements in cognitive flexibility. In these models, greater baseline dFC was associated with better baseline cognitive flexibility but less improvement in cognitive flexibility. These findings suggest a nuanced relationship between cognitive and neural flexibility. Whereas some enduring increases in neural dynamics may allow for shifting out of a maladaptively rigid state, larger persisting increases in neural dynamics may be of less benefit to psilocybin therapy.

A potential effect of psilocybin on anxiety in neurotic personality structures in adolescents

A potential effect of psilocybin on anxiety in neurotic personality structures in adolescents

Psychedelics, Sociality, and Human Evolution.

Our hominin ancestors inevitably encountered and likely ingested psychedelic mushrooms throughout their evolutionary history. This assertion is supported by current understanding of: early hominins’ paleodiet and paleoecology; primate phylogeny of mycophagical and self-medicative behaviors; and the biogeography of psilocybin-containing fungi. These lines of evidence indicate mushrooms (including bioactive species) have been a relevant resource since the Pliocene, when hominins intensified exploitation of forest floor foods. Psilocybin and similar psychedelics that primarily target the serotonin 2A receptor subtype stimulate an active coping strategy response that may provide an enhanced capacity for adaptive changes through a flexible and associative mode of cognition. Such psychedelics also alter emotional processing, self-regulation, and social behavior, often having enduring effects on individual and group well-being and sociality. A homeostatic and drug instrumentalization perspective suggests that incidental inclusion of psychedelics in the diet of hominins, and their eventual addition to rituals and institutions of early humans could have conferred selective advantages. Hominin evolution occurred in an ever-changing, and at times quickly changing, environmental landscape and entailed advancement into a socio-cognitive niche, i.e., the development of a socially interdependent lifeway based on reasoning, cooperative communication, and social learning. In this context, psychedelics’ effects in enhancing sociality, imagination, eloquence, and suggestibility may have increased adaptability and fitness. We present interdisciplinary evidence for a model of psychedelic instrumentalization focused on four interrelated instrumentalization goals: management of psychological distress and treatment of health problems; enhanced social interaction and interpersonal relations; facilitation of collective ritual and religious activities; and enhanced group decision-making. The socio-cognitive niche was simultaneously a selection pressure and an adaptive response, and was partially constructed by hominins through their activities and their choices. Therefore, the evolutionary scenario put forward suggests that integration of psilocybin into ancient diet, communal practice, and proto-religious activity may have enhanced hominin response to the socio-cognitive niche, while also aiding in its creation. In particular, the interpersonal and prosocial effects of psilocybin may have mediated the expansion of social bonding mechanisms such as laughter, music, storytelling, and religion, imposing a systematic bias on the selective environment that favored selection for prosociality in our lineage.

Psilocybin Induces Aberrant Prediction Error Processing of Tactile Mismatch Responses-A Simultaneous EEG-FMRI Study.

As source of sensory information, the body provides a sense of agency and self/non-self-discrimination. The integration of bodily states and sensory inputs with prior beliefs has been linked to the generation of bodily self-consciousness. The ability to detect surprising tactile stimuli is essential for the survival of an organism and for the formation of mental body representations. Despite the relevance for a variety of psychiatric disorders characterized by altered body and self-perception, the neurobiology of these processes is poorly understood. We therefore investigated the effect of psilocybin (Psi), known to induce alterations in self-experience, on tactile mismatch responses by combining pharmacological manipulations with simultaneous electroencephalography-functional magnetic resonance imaging (EEG-fMRI) recording. Psi reduced activity in response to tactile surprising stimuli in frontal regions, the visual cortex, and the cerebellum. Furthermore, Psi reduced tactile mismatch negativity EEG responses at frontal electrodes, associated with alterations of body- and self-experience. This study provides first evidence that Psi alters the integration of tactile sensory inputs through aberrant prediction error processing and highlights the importance of the 5-HT2A system in tactile deviancy processing as well as in the integration of bodily and self-related stimuli. These findings may have important implications for the treatment of psychiatric disorders characterized by aberrant bodily self-awareness.

Lasting effects of a single psilocybin dose on resting-state functional connectivity in healthy individuals.

Background:Psilocybin is a psychedelic drug that has shown lasting positive effects on clinical symptoms and self-reported well-being following a single dose. There has been little research into the long-term effects of psilocybin on brain connectivity in humans.Aim:Evaluate changes in resting-state functional connectivity (RSFC) at 1 week and 3 months after one psilocybin dose in 10 healthy psychedelic-naïve volunteers and explore associations between change in RSFC and related measures.Methods:Participants received 0.2–0.3 mg/kg psilocybin in a controlled setting. Participants completed resting-state functional magnetic resonance imaging (fMRI) scans at baseline, 1-week and 3-month post-administration and [11C]Cimbi-36 PET scans at baseline and 1 week. We examined changes in within-network, between-network and region-to-region RSFC. We explored associations between changes in RSFC and psilocybin-induced phenomenology as well as changes in psychological measures and neocortex serotonin 2A receptor binding.Results:Psilocybin was well tolerated and produced positive changes in well-being. At 1 week only, executive control network (ECN) RSFC was significantly decreased (Cohen’s d = −1.73, pFWE = 0.010). We observed no other significant changes in RSFC at 1 week or 3 months, nor changes in region-to-region RSFC. Exploratory analyses indicated that decreased ECN RSFC at 1 week predicted increased mindfulness at 3 months (r = −0.65).Conclusions:These findings in a small cohort indicate that psilocybin affects ECN function within the psychedelic ‘afterglow’ period. Our findings implicate ECN modulation as mediating psilocybin-induced, long-lasting increases in mindfulness. Although our findings implicate a neural pathway mediating lasting psilocybin effects, it is notable that changes in neuroimaging measures at 3 months, when personality changes are observed, remain to be identified.

The need for publicly funded research on therapeutic use of psychedelic drugs.

The need for publicly funded research on therapeutic use of psychedelic drugs.

Effectiveness of Psilocybin on Depression: A Qualitative Study

Introduction: Psilocybin mushroom use is well documented in spiritual and religious ceremonies globally. This drug is now the most popular in Europe and the USA. Objective: The objective of this study is to explore the experiences and effects of psilocybin on patients with depression and anxiety. Method: A qualitative study was conducted interviewing ten participants currently taking psilocybin while experiencing depression and/or anxiety. Ethical approval was obtained from the University ethics committee. Participants were recruited via social media and groups are known to have used psilocybin for the treatment of anxiety and/or depression. Participants were informed of study aims and consent was obtained before interviews commenced. Confidentiality was maintained throughout this study. Interviews began with informing participants that psilocybin may be effective in the management of depression. Initially, information around the way treatment with psilocybin was obtained was sought. This was followed by queries around the effects of the drug in terms of experiences both during and after treatment. Finally, participants were asked to outline the positive effects of psilocybin on their lives. Results: The data were thematically coded using Grounded Theory as an underpinning philosophical paradigm. Emerging themes included enhancement of smell, vision, hearing, and taste sensations. Another theme emerging was the experience of being ‘connected with the universe’ while on the drug. Additionally, participants reported a stabilization of mood, an increase in optimism and emotional control, and a healthier emotional connection with others. Most also felt an increase in comfort, peace and calmness. Another theme that emerged centered on the mechanism of action of psilocybin. Participants stated that this substance seemed to ‘make new connections in their brain,’ resulting in new perspectives. Some participants felt this resulted in a calming influence on the mind and body. This aligns with research showing that psilocybin works by changing the thinking and improving information processing. Conclusion: Psilocybin has promising effects on the patients with depression/anxiety even after a single dose. Psilocybin is safe but the administration should be guided by a health professional to yield safe and positive outcomes.

Psilocybin in the treatment of obsessive-compulsive disorder: What do we know so far?

IntroductionPsilocybin is a naturally occurring plant alkaloid in mushrooms and a prodrug of psilocin. It is a serotonin receptor (5-HT2A) agonist and known psychedelic, with similar hallucinatory properties to lysergic acid diethylamide (LSD). It has been identified as a safe and effective option in treatment-resistant depression. Literature focus mainly on its use on depressive but its interest in other psychiatric disorders such as obsessive-compulsive disorder (OCD) has grown.ObjectivesTo review the clinical evidence for the use of hallucinogens such as psilocybin in OCD.MethodsNon-systematic review of literature found on PubMed/MEDLINE, Web of Science and Google Scholar, using the keywords “obsessive-compulsive disorder”, “psilocybin” and “hallucinogens”. Articles may include clinical trials, case report or case series. Articles found were admitted according to their relevance for the topic in review; only articles in English were included. Ongoing research trials on this topic were checked on ClinicalTrials.gov.ResultsSo far, only one open-label non-randomized study directly assessed the effects of psilocybin on OCD patients that found acute reductions of obsessive-compulsive symptoms. Case reports of patients improving with off-label use of psilocybin are reported. There are two ongoing phase I research trials, aiming to explore the effect of the substance on symptomatology, hypothesizing that psilocybin will normalize cerebral connectivity and thus correlate with clinical improvement.ConclusionsMore research to establish the usefulness of psilocybin in OCD patients is needed; the collected data is encouraging are there may be a role for its use on this disorder.

Effects of psilocybin-assisted therapy on treatment-resistant depression

Introduction Major depressive disorder is a highly prevalent clinical condition, affecting more than 300 million individuals worldwide. About 1/3 of patients with MDD fail to achieve remission despite treatment with multiple antidepressants and are considered to have treatment-resistant depression (TRD). Novel antidepressants with rapid and sustained effects on mood and cognition could represent a breakthrough in the TRD and may potentially improve or save lives. Psilocybin, a classic hallucinogen, more commonly found in the Psilocybe mushrooms has a combined serotonergic and glutamatergic action. The preliminary evidence of antidepressant effects of psilocybin-assisted therapy indicates the potential of psilocybin-assisted therapy as a novel antidepressant intervention.ObjectivesThe authors elaborate a narrative literature review about the effects of Psilocybin-based therapy on patients diagnosed with treatment-resistant depression.MethodsPubMed database searched using the terms “Treatment-Resistant Depression AND Psilocybin” and targeting clinical trials. References of selected articles and review articles were also assessed.Results2 articles evaluate psilocybin effects in 32 patients with TRD and showed that two doses of psilocybin alongside psychological support significantly reduces depressive symptoms. All patients presented some reduction in symptoms from baseline to one week after the second dose and reproduced immediate and substantial improvements in depression that ultimately could sustain up to 6 months.ConclusionsPsilocybin-assisted therapy is a very appealing new possibility in the treatment of depression. However, due to the small populations of the existing trials, future studies are needed to prove this positive association and to fully understand Psilocybin’s mechanisms of actions and effects.DisclosureNo significant relationships.

P.214 (Sub)acute effects of psilocybin on creative cognition: a double-blind, placebo-controlled experimental study

P.214 (Sub)acute effects of psilocybin on creative cognition: a double-blind, placebo-controlled experimental study

The Evolved Psychology of Psychedelic Set and Setting: Inferences Regarding the Roles of Shamanism and Entheogenic Ecopsychology.

This review illustrates the relevance of shamanism and its evolution under effects of psilocybin as a framework for identifying evolved aspects of psychedelic set and setting. Effects of 5HT2 psychedelics on serotonin, stress adaptation, visual systems and personality illustrate adaptive mechanisms through which psychedelics could have enhanced hominin evolution as an environmental factor influencing selection for features of our evolved psychology. Evolutionary psychology perspectives on ritual, shamanism and psychedelics provides bases for inferences regarding psychedelics’ likely roles in hominin evolution as exogenous neurotransmitter sources through their effects in selection for innate dispositions for psychedelic set and setting. Psychedelics stimulate ancient brain structures and innate modular thought modules, especially self-awareness, other awareness, “mind reading,” spatial and visual intelligences. The integration of these innate modules are also core features of shamanism. Cross-cultural research illustrates shamanism is an empirical phenomenon of foraging societies, with its ancient basis in collective hominid displays, ritual alterations of consciousness, and endogenous healing responses. Shamanic practices employed psychedelics and manipulated extrapharmacological effects through stimulation of serotonin and dopamine systems and augmenting processes of the reptilian and paleomammalian brains. Differences between chimpanzee maximal displays and shamanic rituals reveal a zone of proximal development in hominin evolution. The evolution of the mimetic capacity for enactment, dance, music, and imitation provided central capacities underlying shamanic performances. Other chimp-human differences in ritualized behaviors are directly related to psychedelic effects and their integration of innate modular thought processes. Psychedelics and other ritual alterations of consciousness stimulate these and other innate responses such as soul flight and death-and-rebirth experiences. These findings provided bases for making inferences regarding foundations of our evolved set, setting and psychology. Shamanic setting is eminently communal with singing, drumming, dancing and dramatic displays. Innate modular thought structures are prominent features of the set of shamanism, exemplified in animism, animal identities, perceptions of spirits, and psychological incorporation of spirit others. A shamanic-informed psychedelic therapy includes: a preparatory set with practices such as sexual abstinence, fasting and dream incubation; a set derived from innate modular cognitive capacities and their integration expressed in a relational animistic worldview; a focus on internal imagery manifesting a presentational intelligence; and spirit relations involving incorporation of animals as personal powers. Psychedelic research and treatment can adopt this shamanic biogenetic paradigm to optimize set, setting and ritual frameworks to enhance psychedelic effects.

Optimal dosing for psilocybin pharmacotherapy: Considering weight-adjusted and fixed dosing approaches.

Background:Growing evidence suggests psilocybin, a naturally occurring psychedelic, is a safe and promising pharmacotherapy for treatment of mood and substance use disorders when administered as part of a structured intervention. In most trials to date, psilocybin dose has been administered on a weight-adjusted basis rather than the more convenient procedure of administering a fixed dose.Aims:The present post hoc analyses sought to determine whether the subjective effects of psilocybin are affected by body weight when psilocybin is administered on a weight-adjusted basis and when psilocybin is administered as a fixed dose.Methods:We analyzed acute subjective drug effects (mystical, challenging, and intensity) associated with therapeutic outcomes from ten previous studies (total N = 288) in which psilocybin was administered in the range 20 to 30 mg/70 kg (inclusive). Separate multivariate regression analyses examined the relationships between demographic variables including body weight and subjective effects in participants receiving 20 mg/70 kg (n = 120), participants receiving 30 mg/70 kg (n = 182), and participants whose weight-adjusted dose was about 25 mg (to approximate the fixed dose that is currently being evaluated in registration trials for major depressive disorder) (n = 103).Results:In the 20 mg/70 kg and 30 mg/70 kg weight-adjusted groups, and in the fixed dose group, no significant associations were found between subjective effects and demographic variables including body weight or sex. Across a wide range of body weights (49 to 113 kg) the present results showed no evidence that body weight affected subjective effects of psilocybin.Conclusions:These results suggest that the convenience and lower cost of administering psilocybin as a fixed dose outweigh any potential advantage of weight-adjusted dosing.

Psilocybin for the Treatment of Depression: A Promising New Pharmacotherapy Approach.

Depression is highly prevalent and represents the leading cause of global disability and primary contributor to overall global burden of disease. Several lines of evidence from early-phase experimental trials suggest that serotonergic psychedelics, particularly psilocybin, with therapeutic support show great promise in the treatment of depression with large effect sizes. Neuroimaging data have also revealed the dynamic effects of psilocybin on functional activity within and between neural regions. This chapter reviews the methods and findings from three small human laboratory clinical trials examining the effects of psilocybin therapy for patients with major depressive disorder and treatment-resistant depression. Insights from functional magnetic resonance imaging and qualitative analyses are also presented, as well as a discussion of study limitations and future directions for the research.

What is the clinical evidence on psilocybin for the treatment of psychiatric disorders? A systematic review.

Background:Psilocybin is a predominant agonist of 5HT1A and 5HT2A/C receptors and was first isolated in 1958, shortly before it became a controlled substance. Research on the potential therapeutic effects of this compound has recently re-emerged alongside what is being addressed as a psychedelic renaissance.Methods:In this paper we performed a systematic review of the clinical trials conducted so far regarding the therapeutic effects of psilocybin on psychiatric disorders. The eligibility criteria included clinical trials that assessed psilocybin's potential therapeutic effects on patients with psychiatric disorders. Nine hundred seven articles were found and screened in regard to the title, from which 94 were screened through abstract and 9 met the eligibility criteria and were included.Results:The papers published focused on 3 disorders: depression, obsessive-compulsive disorder (OCD) and substance use disorder (namely tobacco and alcohol). Psilocybin has shown a relatively safe profile and very promising results, with reductions found on most of the psychiatric rating scales’ scores. Research on depression showed the most solid evidence, supported by 3 randomized controlled trials. Studies on OCD and substance use disorder showed more limitations due to their open-label design.Conclusions:Altogether, the results from the studies reviewed in this paper suggest a substantial therapeutic potential. This calls for further research to confirm the results observed so far and further explain the underlying mechanisms.

Psilocybin for the Treatment of Obsessive-Compulsive Disorders.

Obsessive-compulsive disorder (OCD) is a highly prevalent and disabling condition for which currently available treatments are insufficiently effective and alternatives merit priority attention. Psilocybin may represent a safe and effective avenue for treatment of individuals affected by this condition. In this chapter we briefly introduce OCD symptoms, epidemiology, as well as relevant hypotheses on the mechanism of disease that may inform treatment interventions. We briefly describe currently available treatments, mechanisms of action, and efficacy limitations, as preamble to the potential use of psilocybin and perhaps similar compounds in the treatment of OCD and related conditions. Although much is reviewed throughout this book about the mechanisms of action of psychedelic agents, a focused discussion of psilocybin effects as they pertain to OCD is also included. Our experience with incidental observation, prospective research, and current explorations of psilocybin in OCD are also described.

Psilocybin – mechanism of action and clinical evidence – systematic review

Background. Research into the potential therapeutic applications of psilocybin has been ongoing for decades, with recent studies showing promising results in treating mental health conditions such as depression, anxiety, and addiction. Methods. The clinical trials that have been conducted so far regarding the therapeutic effects of psilocybin on psychiatric disorders were systematically reviewed in this article. PubMed, MEDLINE and Google Scholar databases were searched from January 1980 to March 2023. 17 articles met the eligibility criteria after identification and screening for title and abstract. Results. Articles were divided into groups according to the psychiatric disorder addressed. 13 articles studied the efficiency of psilocybin in the treatment of depressive symptoms. 10 articles were randomized or open-label trials with a range of 12 to 59 patients and 3 were follow-ups. 5 out of the 13 articles explored psilocybin efficiency in patients with anxiety and depression disorders in correlation to life-threatening diseases (different stages of cancer or HIV). Only one open-label trial addressed psilocybin effect in patients with obsessive compulsive disorder. 3 studies assessed psilocybin efficiency regarding addictions treatment: alcohol addiction (one open-label trial) and tobacco addiction (one open-label trial and one follow-up). Conclusions. Psilocybin shows promise as a potential therapeutic agent for various mental health conditions. Further research on larger groups of patients is needed to fully understand the therapeutic potential of psilocybin and to optimize dosing protocols and minimize potential adverse effects.

Investigating the role of 5-HT2A and 5-HT2C receptor activation in the effects of psilocybin, DOI, and citalopram on marble burying in mice

Psychedelic drugs acting as 5-hydroxyptryptamine 2A receptor (5-HT2AR) agonists have shown promise as viable treatments of psychiatric disorders, including obsessive-compulsive disorder. The marble burying test is a test of compulsive-like behavior in mice, and psychedelics acting as 5-HT2AR agonists can reduce digging in this test. We assessed the 5-HT2R contribution to the mechanisms of two 5-HT2A agonists on digging behavior in female NMRI mice, using citalopram as a reference compound. While the 5-HT2AR antagonist M100907 blocked the effect of DOI and the 5-HT2CR antagonist SB242084 blocked the effect of citalopram, neither antagonist blocked the effect of psilocybin. This study confirms 5-HT2AR agonism as a mechanism for reduced compulsive-like digging in the MB test and suggests that 5-HT2A and 5-HT2CRs can work in parallel on this type of behavior. Our results with psilocybin suggest that a 5-HT2R-independent mechanism also contributes to the effect of psilocybin on repetitive digging behavior.

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

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.

Transcriptional regulation in the rat prefrontal cortex and hippocampus after a single administration of psilocybin

Psilocybin is a serotonergic psychedelic found in "magic mushrooms" with a putative therapeutic potential for treatment-resistant depression, anxiety, obsessive-compulsive disorder, and addiction. In rodents, psilocybin acutely induces plasticity-related immediate early genes in cortical tissue; however, studies into the effects on subcortical regions, of different doses, and the subsequent translation of corresponding proteins are lacking. We examined the acute effects of a single administration of psilocybin (0.5-20 mg/kg) on the expression of selected genes in the prefrontal cortex and hippocampus. In total, 46 target genes and eight reference genes were assessed using real-time quantitative polymerase chain reaction. Corresponding protein levels of the three most commonly regulated genes were assessed using Western blotting. In the prefrontal cortex, psilocybin increased the expression of Cebpb, c-Fos, Dups1, Fosb, Junb, Iκβ-α, Nr4a1, P11, Psd95, and Sgk1, and decreased the expression of Clk1. In the hippocampus, psilocybin strongly increased the expression of Arrdc2, Dusp1, Iκβ-α, and Sgk1 in a dose-dependent manner, and decreased the expression of Arc, Clk1, Egr2, and Ptgs2. Protein levels of Sgk1, Dusp1, and Iκβ-α showed only partial agreement with transcriptional patterns, stressing the importance of assessing downstream translation when investigating rapid gene responses. The present study demonstrates that psilocybin rapidly induces gene expression related to neuroplasticity, biased towards the prefrontal cortex, compared to the hippocampus. Our findings provide further evidence for the rapid plasticity-promoting effects of psilocybin.