Changes in aminoacidergic and monoaminergic neurotransmission in the hippocampus and amygdala of rats after ayahuasca ingestion

Effects of psychedelics on neurogenesis and broader neuroplasticity: a systematic review

In the mammalian brain, new neurons continue to be generated throughout life in a process known as adult neurogenesis. The role of adult-generated neurons has been broadly studied across laboratories, and mounting evidence suggests a strong link to the HPA axis and concomitant dysregulations in patients diagnosed with mood disorders. Psychedelic compounds, such as phenethylamines, tryptamines, cannabinoids, and a variety of ever-growing chemical categories, have emerged as therapeutic options for neuropsychiatric disorders, while numerous reports link their effects to increased adult neurogenesis. In this systematic review, we examine studies assessing neurogenesis or other neurogenesis-associated brain plasticity after psychedelic interventions and aim to provide a comprehensive picture of how this vast category of compounds regulates the generation of new neurons. We conducted a literature search on PubMed and Science Direct databases, considering all articles published until January 31, 2023, and selected articles containing both the words "neurogenesis" and "psychedelics". We analyzed experimental studies using either in vivo or in vitro models, employing classical or atypical psychedelics at all ontogenetic windows, as well as human studies referring to neurogenesis-associated plasticity. Our findings were divided into five main categories of psychedelics: CB1 agonists, NMDA antagonists, harmala alkaloids, tryptamines, and entactogens. We described the outcomes of neurogenesis assessments and investigated related results on the effects of psychedelics on brain plasticity and behavior within our sample. In summary, this review presents an extensive study into how different psychedelics may affect the birth of new neurons and other brain-related processes. Such knowledge may be valuable for future research on novel therapeutic strategies for neuropsychiatric disorders.

Neurobiological research on N,N-dimethyltryptamine (DMT) and its potentiation by monoamine oxidase (MAO) inhibition: from ayahuasca to synthetic combinations of DMT and MAO inhibitors

The potent hallucinogen N,N-dimethyltryptamine (DMT) has garnered significant interest in recent years due to its profound effects on consciousness and its therapeutic psychopotential. DMT is an integral (but not exclusive) psychoactive alkaloid in the Amazonian plant-based brew ayahuasca, in which admixture of several β-carboline monoamine oxidase A (MAO-A) inhibitors potentiate the activity of oral DMT, while possibly contributing in other respects to the complex psychopharmacology of ayahuasca. Irrespective of the route of administration, DMT alters perception, mood, and cognition, presumably through agonism at serotonin (5-HT) 1A/2A/2C receptors in brain, with additional actions at other receptor types possibly contributing to its overall psychoactive effects. Due to rapid first pass metabolism, DMT is nearly inactive orally, but co-administration with β-carbolines or synthetic MAO-A inhibitors (MAOIs) greatly increase its bioavailability and duration of action. The synergistic effects of DMT and MAOIs in ayahuasca or synthetic formulations may promote neuroplasticity, which presumably underlies their promising therapeutic efficacy in clinical trials for neuropsychiatric disorders, including depression, addiction, and post-traumatic stress disorder. Advances in neuroimaging techniques are elucidating the neural correlates of DMT-induced altered states of consciousness, revealing alterations in brain activity, functional connectivity, and network dynamics. In this comprehensive narrative review, we present a synthesis of current knowledge on the pharmacology and neuroscience of DMT, β-carbolines, and ayahuasca, which should inform future research aiming to harness their full therapeutic potential.

Dysfunctional hippocampal-prefrontal network underlies a multidimensional neuropsychiatric phenotype following early-life seizure

Brain disturbances during development can have a lasting impact on neural function and behavior. Seizures during this critical period are linked to significant long-term consequences such as neurodevelopmental disorders, cognitive impairments, and psychiatric symptoms, resulting in a complex spectrum of multimorbidity. The hippocampus-prefrontal cortex (HPC-PFC) circuit emerges as a potential common link between such disorders. However, the mechanisms underlying these outcomes and how they relate to specific behavioral alterations are unclear. We hypothesized that specific dysfunctions of hippocampal-cortical communication due to early-life seizure would be associated with distinct behavioral alterations observed in adulthood. Here, we performed a multilevel study to investigate behavioral, electrophysiological, histopathological, and neurochemical long-term consequences of early-life Status epilepticus in male rats. We show that adult animals submitted to early-life seizure (ELS) present working memory impairments and sensorimotor disturbances, such as hyperlocomotion, poor sensorimotor gating, and sensitivity to psychostimulants despite not exhibiting neuronal loss. Surprisingly, cognitive deficits were linked to an aberrant increase in the HPC-PFC long-term potentiation (LTP) in a U-shaped manner, while sensorimotor alterations were associated with heightened neuroinflammation, as verified by glial fibrillary acidic protein (GFAP) expression, and altered dopamine neurotransmission. Furthermore, ELS rats displayed impaired HPC-PFC theta-gamma coordination and an abnormal brain state during active behavior resembling rapid eye movement (REM) sleep oscillatory dynamics. Our results point to impaired HPC-PFC functional connectivity as a possible pathophysiological mechanism by which ELS can cause cognitive deficits and psychiatric-like manifestations even without neuronal loss, bearing translational implications for understanding the spectrum of multidimensional developmental disorders linked to early-life seizures.

Ayahuasca and its major component harmine promote antinociceptive effects in mouse models of acute and chronic pain

ETHNOPHARMACOLOGICAL RELEVANCE

Ayahuasca (AYA) is a psychedelic brew used in religious ceremonies. It is broadly used as a sacred medicine for treating several ailments, including pain of various origins.

AIM OF THE STUDY

To investigate the antinociceptive effects of AYA and its mechanisms in preclinical models of acute and chronic pain in mice, in particular during experimental neuropathy.

MATERIALS AND METHODS

The antinociceptive effects of AYA administered orally were assessed in the following models of pain: formalin test, Complete Freund's Adjuvant (CFA)-induced inflammation, tail flick test, and partial sciatic nerve ligation model of neuropathic pain. Antagonism assays and Fos immunohistochemistry in the brain were performed. AYA-induced toxicity was investigated. AYA was chemically characterized. The antinociceptive effect of harmine, the major component present in AYA, was investigated.

RESULTS

AYA (24-3000 μL/kg) dose-dependently reduced formalin-induced pain-like behaviors and CFA-induced mechanical allodynia but did not affect CFA-induced paw edema or tail flick latency. During experimental neuropathy, single treatments with AYA (24-3000 μL/kg) reduced mechanical allodynia; daily treatments once or twice a day for 14 days promoted consistent and sustained antinociception. The antinociceptive effect of AYA (600 μL/kg) was reverted by bicuculline (1 mg/kg) and methysergide (5 mg/kg), but not by naloxone (5 mg/kg), phaclofen (2 mg/kg), and rimonabant (10 mg/kg), suggesting the roles of GABAA and serotonergic receptors. AYA increased Fos expression in the ventrolateral periaqueductal gray and nucleus raphe magnus after 1 h, but not after 6 h or 14 days of daily treatments. AYA (600 μL/kg) twice a day for 14 days did not alter mice's motor function, spontaneous locomotion, body weight, food and water intake, hematological, biochemical, and histopathological parameters. Harmine (3.5 mg/kg) promoted consistent antinociception during experimental neuropathy.

CONCLUSIONS

AYA promotes consistent antinociceptive effects in different mouse models of pain without inducing detectable toxic effects. Harmine is at least partially accountable for the antinociceptive properties of AYA.

The Effects of Psychedelics on Neuronal Physiology

Psychedelics are quite unique among drugs that impact the central nervous system, as a single administration of a psychedelic can both rapidly alter subjective experience in profound ways and produce sustained effects on circuits relevant to mood, fear, reward, and cognitive flexibility. These remarkable properties are a direct result of psychedelics interacting with several key neuroreceptors distributed across the brain. Stimulation of these receptors activates a variety of signaling cascades that ultimately culminate in changes in neuronal structure and function. Here, we describe the effects of psychedelics on neuronal physiology, highlighting their acute effects on serotonergic and glutamatergic neurotransmission as well as their long-lasting effects on structural and functional neuroplasticity in the cortex. We propose that the neurobiological changes leading to the acute and sustained effects of psychedelics might be distinct, which could provide opportunities for engineering compounds with optimized safety and efficacy profiles.

Effects of Bradykinin B2 Receptor Ablation from Tyrosine Hydroxylase Cells on Behavioral and Motor Aspects in Male and Female Mice

The kallikrein-kinin system is a versatile regulatory network implicated in various biological processes encompassing inflammation, nociception, blood pressure control, and central nervous system functions. Its physiological impact is mediated through G-protein-coupled transmembrane receptors, specifically the B1 and B2 receptors. Dopamine, a key catecholamine neurotransmitter widely distributed in the CNS, plays a crucial role in diverse physiological functions including motricity, reward, anxiety, fear, feeding, sleep, and arousal. Notably, the potential physical interaction between bradykinin and dopaminergic receptors has been previously documented. In this study, we aimed to explore whether B2R modulation in catecholaminergic neurons influences the dopaminergic pathway, impacting behavioral, metabolic, and motor aspects in both male and female mice. B2R ablation in tyrosine hydroxylase cells reduced the body weight and lean mass without affecting body adiposity, substrate oxidation, locomotor activity, glucose tolerance, or insulin sensitivity in mice. Moreover, a B2R deficiency in TH cells did not alter anxiety levels, exercise performance, or motor coordination in female and male mice. The concentrations of monoamines and their metabolites in the substantia nigra and cortex region were not affected in knockout mice. In essence, B2R deletion in TH cells selectively influenced the body weight and composition, leaving the behavioral and motor aspects largely unaffected.

The Psychedelic Future of Post-Traumatic Stress Disorder Treatment

Post-traumatic stress disorder (PTSD) is a mental health condition that can occur following exposure to a traumatic experience. An estimated 12 million U.S. adults are presently affected by this disorder. Current treatments include psychological therapies (e.g., exposure-based interventions) and pharmacological treatments (e.g., selective serotonin reuptake inhibitors (SSRIs)). However, a significant proportion of patients receiving standard-of-care therapies for PTSD remain symptomatic, and new approaches for this and other trauma-related mental health conditions are greatly needed. Psychedelic compounds that alter cognition, perception, and mood are currently being examined for their efficacy in treating PTSD despite their current status as Drug Enforcement Administration (DEA)- scheduled substances. Initial clinical trials have demonstrated the potential value of psychedelicassisted therapy to treat PTSD and other psychiatric disorders. In this comprehensive review, we summarize the state of the science of PTSD clinical care, including current treatments and their shortcomings. We review clinical studies of psychedelic interventions to treat PTSD, trauma-related disorders, and common comorbidities. The classic psychedelics psilocybin, lysergic acid diethylamide (LSD), and N,N-dimethyltryptamine (DMT) and DMT-containing ayahuasca, as well as the entactogen 3,4-methylenedioxymethamphetamine (MDMA) and the dissociative anesthetic ketamine, are reviewed. For each drug, we present the history of use, psychological and somatic effects, pharmacology, and safety profile. The rationale and proposed mechanisms for use in treating PTSD and traumarelated disorders are discussed. This review concludes with an in-depth consideration of future directions for the psychiatric applications of psychedelics to maximize therapeutic benefit and minimize risk in individuals and communities impacted by trauma-related conditions.

Natural psychedelics in the treatment of depression; a review focusing on neurotransmitters

Natural psychedelic compounds are emerging as potential novel therapeutics in psychiatry. This review will discuss how natural psychedelics exert their neurobiological therapeutic effects, and how different neurotransmission systems mediate the effects of these compounds. Further, current therapeutic strategies for depression, and novel mechanism of action of natural psychedelics in the treatment of depression will be discussed. In this review, our focus will be on N, N-dimethyltryptamine (DMT), reversible type A monoamine oxidase inhibitors, mescaline-containing cacti, psilocybin/psilocin-containing mushrooms, ibogaine, muscimol extracted from Amanita spp. mushrooms and ibotenic acid.

The current state of ayahuasca research in animal models: A systematic review

RATIONALE

The psychedelic brew ayahuasca is increasingly being investigated for its therapeutic potential. Animal models are essential to investigate the pharmacological effects of ayahuasca since they can control important factors influencing it, such as the set and setting.

OBJECTIVE

Review and summarise data available on ayahuasca research using animal models.

METHODS

We systematically searched five databases (PubMed, Web of Science, EMBASE, LILACS and PsycInfo) for peer-reviewed studies in English, Portuguese or Spanish published up to July 2022. The search strategy included ayahuasca- and animal model-related terms adapted from the SYRCLE search syntax.

RESULTS

We identified 32 studies investigating ayahuasca effects on toxicological, behavioural and (neuro)biological parameters in rodents, primates and zebrafish. Toxicological results show that ayahuasca is safe at ceremonial-based doses but toxic at high doses. Behavioural results indicate an antidepressant effect and a potential to reduce the reward effects of ethanol and amphetamines, while the anxiety-related outcomes are yet inconclusive; also, ayahuasca can influence locomotor activity, highlighting the importance of controlling the analysis for locomotion when using tasks depending on it. Neurobiological results show that ayahuasca affects brain structures involved in memory, emotion and learning and that other neuropathways, besides the serotonergic action, are important in modulating its effects.

CONCLUSIONS

Studies using animal models indicate that ayahuasca is toxicologically safe in ceremonial-comparable doses and indicates a therapeutic potential for depression and substance use disorder while not supporting an anxiolytic effect. Essential gaps in the ayahuasca field can still be sufficed using animal models.

Molecular Pathways of the Therapeutic Effects of Ayahuasca, a Botanical Psychedelic and Potential Rapid-Acting Antidepressant

Ayahuasca is a psychoactive brew traditionally used in indigenous and religious rituals and ceremonies in South America for its therapeutic, psychedelic, and entheogenic effects. It is usually prepared by lengthy boiling of the leaves of the bush Psychotria viridis and the mashed stalks of the vine Banisteriopsis caapi in water. The former contains the classical psychedelic N,N-dimethyltryptamine (DMT), which is thought to be the main psychoactive alkaloid present in the brew. The latter serves as a source for β-carbolines, known for their monoamine oxidase-inhibiting (MAOI) properties. Recent preliminary research has provided encouraging results investigating ayahuasca’s therapeutic potential, especially regarding its antidepressant effects. On a molecular level, pre-clinical and clinical evidence points to a complex pharmacological profile conveyed by the brew, including modulation of serotoninergic, glutamatergic, dopaminergic, and endocannabinoid systems. Its substances also interact with the vesicular monoamine transporter (VMAT), trace amine-associated receptor 1 (TAAR1), and sigma-1 receptors. Furthermore, ayahuasca’s components also seem to modulate levels of inflammatory and neurotrophic factors beneficially. On a biological level, this translates into neuroprotective and neuroplastic effects. Here we review the current knowledge regarding these molecular interactions and how they relate to the possible antidepressant effects ayahuasca seems to produce.

Overcoming epistemic injustices in the biomedical study of ayahuasca: Towards ethical and sustainable regulation

After decades of biomedical research on ayahuasca's molecular compounds and their physiological effects, recent clinical trials show evidence of therapeutic potential for depression. However, indigenous peoples have been using ayahuasca therapeutically for a very long time, and thus we question the epistemic authority attributed to scientific studies, proposing that epistemic injustices were committed with practical, cultural, social, and legal consequences. We question epistemic authority based on the double-blind design, the molecularization discourse, and contextual issues about safety. We propose a new approach to foster epistemically fair research, outlining how to enforce indigenous rights, considering the Brazilian, Peruvian, and Colombian cases. Indigenous peoples have the right to maintain, control, protect, and develop their biocultural heritage, traditional knowledge, and cultural expressions, including traditional medicine practices. New regulations about ayahuasca must respect the free, prior, and informed consent of indigenous peoples according to the International Labor Organization Indigenous and Tribal Peoples Convention no. 169. The declaration of the ayahuasca complex as a national cultural heritage may prevent patenting from third parties, fostering the development of traditional medicine. When involving isolated compounds derived from traditional knowledge, benefit-sharing agreements are mandatory according to the United Nations' Convention on Biological Diversity. Considering the extremely high demand to treat millions of depressed patients, the medicalization of ayahuasca without adequate regulation respectful of indigenous rights can be detrimental to indigenous peoples and their management of local environments, potentially harming the sustainability of the plants and of the Amazon itself, which is approaching its dieback tipping point.

Evidence on the impairing effects of Ayahuasca on fear memory reconsolidation

RATIONALE

To uncover whether psychedelic drugs attenuate fear memory responses would advance the development of better psychedelic-based treatments for posttraumatic stress disorder (PTSD). Ayahuasca (AYA), a psychedelic brew containing indolamine N, N-dimethyltryptamine (DMT) and β-carbolines, facilitates fear extinction and improves neural plasticity. Upon retrieval, fear memory undergoes labilization and reconsolidation; however, the effects of AYA on this memory stabilization phase are unknown.

OBJECTIVES

We aimed to investigate the effects of AYA treatment on fear memory reconsolidation.

METHODS

Fear-conditioned Wistar rats received AYA (60, 120, or 240 mg/kg) or H₂O orally via gavage o.g. 20 min before, immediately, or 3 h after a short retrieval session. Analysis of AYA through liquid chromatography-tandem mass spectrometry was used to determine the content of DMT and β-carbolines in AYA.

RESULTS

AYA impaired fear memory reconsolidation when given 20 min before or 3 h after memory retrieval, with the dose of 60 mg/kg being effective at both moments. This dose of AYA was devoid of anxiolytic effect. Importantly, during retrieval, AYA did not change fear expression. The lack of retrieval abolished the reconsolidation impairing effect of AYA. The effects of AYA treatment 20 min before or 3 h after memory retrieval lasted at least 22 days, suggesting no spontaneous recovery of fear memory. Fear memory impairments induced by AYA treatment, at both moments, do not show reinstatement.

CONCLUSIONS

Our findings support the view that a low dose of AYA treatment impairs early and late stages of memory reconsolidation instead of facilitating fear extinction.

Psilocybin for Trauma-Related Disorders

Posttraumatic stress disorder (PTSD) is a debilitating, chronic disorder and efficacy rates of current PTSD treatments are underwhelming. There is a critical need for innovative approaches. We provide an overview of trauma and PTSD and cite literature providing converging evidence of the therapeutic potential of psilocybin for PTSD. No study to date has investigated psilocybin or psilocybin-assisted psychotherapy (PAP) as treatments for PTSD. An open-label study in traumatized AIDS survivors found that PAP reduced PTSD symptoms, attachment anxiety, and demoralization. Several PAP trials show preliminary efficacy in facilitating confronting traumatic memories, decreasing emotional avoidance, depression, anxiety, pessimism, and disconnection from others, and increasing acceptance, self-compassion, and forgiveness of abusers, all of which are relevant to PTSD recovery. There is also early evidence that other classic psychedelics may produce large reductions in PTSD symptoms in combat veterans. However, this body of literature is small, mechanisms are not yet well understood, and the risks of using psychedelic compounds for trauma-related disorders need further study. In sum, evidence supports further investigation of PAP as a radically new approach for treating PTSD.

Clinical and biological predictors of psychedelic response in the treatment of psychiatric and addictive disorders: A systematic review

BACKGROUND

The use of psychedelic treatments has shown very promising results in some psychiatric and addictive disorders, but not all patients achieved a response.

AIM

The aim of this review is to explore the clinical and biological factors which could predict the response to psychedelics in psychiatric and addictive disorders.

METHODS

A systematic research was performed on MEDLINE, PsycInfo, Web of science, and Scopus databases from January 1990 to May 2020. All studies investigating the predictive factors of response to psychedelics regardless of psychiatric or addictive disorders, were included.

RESULTS

Twenty studies investigating addictive disorder, treatment-resistant depression, obsessive-compulsive disorder and depressive and anxiety symptoms in patients with life-threatening cancer were included in this review. We found that, in all indications, the main predictive factor of response to psychedelics is the intensity of the acute psychedelic experience. Indeed, we found this factor for alcohol and tobacco use disorders, treatment-resistant depression, and anxiety and depressive symptoms in patients with life-threatening cancer, but not for obsessive-compulsive disorder.

CONCLUSION

The intensity of the acute psychedelic experience was the main predicting factor of response. The action mechanism of this experience was not clear, but some hypotheses could be made, such as a modulation of serotoninergic system by 5-HT2A receptors agonism, a modulation of the default mode network (DMN) with an acute modular disintegration of the DMN followed by a re-integration of this network with a normal functioning, or an anti-inflammatory effect of this treatment.

Psychedelics in Psychiatry: Neuroplastic, Immunomodulatory, and Neurotransmitter Mechanisms

Mounting evidence suggests safety and efficacy of psychedelic compounds as potential novel therapeutics in psychiatry. Ketamine has been approved by the Food and Drug Administration in a new class of antidepressants, and 3,4-methylenedioxymethamphetamine (MDMA) is undergoing phase III clinical trials for post-traumatic stress disorder. Psilocybin and lysergic acid diethylamide (LSD) are being investigated in several phase II and phase I clinical trials. Hence, the concept of psychedelics as therapeutics may be incorporated into modern society. Here, we discuss the main known neurobiological therapeutic mechanisms of psychedelics, which are thought to be mediated by the effects of these compounds on the serotonergic (via 5-HT_2A and 5-HT_1A receptors) and glutamatergic [via N-methyl-d-aspartate (NMDA) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors] systems. We focus on 1) neuroplasticity mediated by the modulation of mammalian target of rapamycin-, brain-derived neurotrophic factor-, and early growth response-related pathways; 2) immunomodulation via effects on the hypothalamic-pituitary-adrenal axis, nuclear factor ĸB, and cytokines such as tumor necrosis factor-α and interleukin 1, 6, and 10 production and release; and 3) modulation of serotonergic, dopaminergic, glutamatergic, GABAergic, and norepinephrinergic receptors, transporters, and turnover systems. We discuss arising concerns and ways to assess potential neurobiological changes, dependence, and immunosuppression. Although larger cohorts are required to corroborate preliminary findings, the results obtained so far are promising and represent a critical opportunity for improvement of pharmacotherapies in psychiatry, an area that has seen limited therapeutic advancement in the last 20 years. Studies are underway that are trying to decouple the psychedelic effects from the therapeutic effects of these compounds. SIGNIFICANCE STATEMENT: Psychedelic compounds are emerging as potential novel therapeutics in psychiatry. However, understanding of molecular mechanisms mediating improvement remains limited. This paper reviews the available evidence concerning the effects of psychedelic compounds on pathways that modulate neuroplasticity, immunity, and neurotransmitter systems. This work aims to be a reference for psychiatrists who may soon be faced with the possibility of prescribing psychedelic compounds as medications, helping them assess which compound(s) and regimen could be most useful for decreasing specific psychiatric symptoms.

Toxicokinetics and Toxicodynamics of Ayahuasca Alkaloids N,N-Dimethyltryptamine (DMT), Harmine, Harmaline and Tetrahydroharmine: Clinical and Forensic Impact

Ayahuasca is a hallucinogenic botanical beverage originally used by indigenous Amazonian tribes in religious ceremonies and therapeutic practices. While ethnobotanical surveys still indicate its spiritual and medicinal uses, consumption of ayahuasca has been progressively related with a recreational purpose, particularly in Western societies. The ayahuasca aqueous concoction is typically prepared from the leaves of the N,N-dimethyltryptamine (DMT)-containing Psychotria viridis, and the stem and bark of Banisteriopsis caapi, the plant source of harmala alkaloids. Herein, the toxicokinetics and toxicodynamics of the psychoactive DMT and harmala alkaloids harmine, harmaline and tetrahydroharmine, are comprehensively covered, particularly emphasizing the psychological, physiological, and toxic effects deriving from their concomitant intake. Potential therapeutic utility, particularly in mental and psychiatric disorders, and forensic aspects of DMT and ayahuasca are also reviewed and discussed. Following administration of ayahuasca, DMT is rapidly absorbed and distributed. Harmala alkaloids act as potent inhibitors of monoamine oxidase A (MAO-A), preventing extensive first-pass degradation of DMT into 3-indole-acetic acid (3-IAA), and enabling sufficient amounts of DMT to reach the brain. DMT has affinity for a variety of serotonergic and non-serotonergic receptors, though its psychotropic effects are mainly related with the activation of serotonin receptors type 2A (5-HT_2A). Mildly to rarely severe psychedelic adverse effects are reported for ayahuasca or its alkaloids individually, but abuse does not lead to dependence or tolerance. For a long time, the evidence has pointed to potential psychotherapeutic benefits in the treatment of depression, anxiety, and substance abuse disorders; and although misuse of ayahuasca has been diverting attention away from such clinical potential, research onto its therapeutic effects has now strongly resurged.

Biodiversity of β-Carboline Profile of Banisteriopsis caapi and Ayahuasca, a Plant and a Brew with Neuropharmacological Potential

Ayahuasca is a psychoactive infusion with a large pharmacological application normally prepared with Banisteriopsis caapi, which contains the monoamine oxidase inhibitors β-carbolines, and Psichotria virids, which contains the serotonin receptor agonist N,N dimethyltryptamine (DMT). The objectives of this study were to investigate the chemical profile of B. caapi and of ayahuasca collected in various Brazilian regions. In total, 176 plant lianas, of which 159 B.caapi and 33 ayahuasca samples were analyzed. Dried liana samples were powdered, extracted with methanol, diluted, and analyzed by LC-MS/MS. Ayahuasca samples were diluted and analyzed. Mean concentrations in B. caapi were 4.79 mg/g harmine, 0.451 mg/g harmaline, and 2.18 mg/g tetrahydroharmine (THH), with a high variability among the samples (RSD from 78.9 to 170%). Native B. caapi samples showed significantly higher harmine concentrations than cultivated ones, and samples from the Federal District/Goiás had higher THH content than those collected in the State of Acre. The other Malpighiaceae samples did not contain β-carbolines, except for one D. pubipetala sample. Concentrations in ayahuasca samples ranged from 0.109 to 7.11 mg/mL harmine, 0.012 to 0.945 mg/mL harmaline, 0.09 to 3.05 mg/mL THH, and 0.10 to 3.12 mg/mL DMT. The analysis of paired ayahuasca/B. caapi confirmed that harmine is reduced to harmaline and to THH during the brew preparation. This is the largest study conducted with Malpighiaceae samples and showed a large variability in the main β-carbolines present in B. caapi. This biodiversity is a challenge for standardization of the material used in ethnopharmacological studies of B.caapi and ayahuasca.

Toxicity of ayahuasca after 28 days daily exposure and effects on monoamines and brain-derived neurotrophic factor (BDNF) in brain of Wistar rats

Ayahuasca is a hallucinogenic beverage that affects the serotonergic system and have therapeutic potential for many diseases and disorders, including depression and drug addiction. The objectives of this study were to evaluate the potential toxic effects of ayahuasca on rats after chronic exposure, and the levels of monoamines, their metabolites and the brain-derived neurotrophic factor (BDNF) in the brain. Female and male rats were treated orally for 28 days with H₂O (control), fluoxetine (FLX), a selective serotonin reuptake inhibitor antidepressant, or ayahuasca (Aya) at doses of 0.5X, 1X and 2X the ritualistic dose (7 to 10 animals/group). Clinical, hematological and macroscopic results showed that ayahuasca was safe to the rats. Behavior tests conducted one hour after the last treatment showed that male rats from the Aya1 group explored the open field central area less than the control group, and the number of entries in the central area compared to total locomotion was also significantly lower in this group and in the FLX group. The hippocampus was removed for BDNF analysis and the remaining brain was used for monoamine analysis by HPLC-FL. Serotonin levels were significantly higher than control only in the Aya2 female group, while a significant reduction of its metabolite 5-HIAA was observed in the FLX group. Dopamine levels were similar among the experimental groups, but the levels of its metabolite DOPAC increased significantly in the Aya1 and Aya2 groups compared to controls, especially in females, and the DOPAC/dopamine turnover was significantly higher in Aya2 group. The levels of HVA, another dopamine metabolite, did not change with the treatments compared to controls, but HVA/DOPAC ratio was significantly lower in all ayahuasca male groups. Norepinephrine was not detected in any brain sample, and the levels of its metabolite MHPG did not change significantly among the groups. BDNF levels in the hippocampus were significantly higher in the FLX and Aya2 female groups compared to controls when expressed in relation to the total brain weight. The mechanisms involved in the increase in serotonin, dopamine turnover and BDNF levels observed in ayahuasca treated animals should be further investigated in specific brain areas.

Ayahuasca: Uses, Phytochemical and Biological Activities

Ayahuasca (caapi, yajé), is a psychoactive brew from the Amazon Basin region of South America traditionally considered a "master plant." It is prepared as a decoction from Banisteriopsis caapi and Psychotria viridis, which it is thought that it stimulates creative thinking and visual creativity. Native healers of the Orinoco and Amazon basins have used traditionally ayahuasca as a healing tool for multiple purposes, particularly to treat psychological disorders in the patients, with some beneficial effects experimentally and clinically validated. Recently, several syncretic religions, as the "União de Vegetal" (UDV) group in Brazil, have been spread around the world. The use of ayahuasca has been popularized by internet and smart-shops, bringing the psychoactive substance to new highs, emerging new "ayahuasqueros." Ayahuasca has alkaloids as β-carbolines and dimethyltryptamines, which inhibit the monoamine oxidase and active the 5-HT2A (5-hydroxytryptamine) receptor, respectively, resulting in hallucinations in the users. Ayahuasca induces a psychedelic change in the anteroposterior coupling of the electrophysiological brain oscillations in humans. Traditional ayahuasca beverage is generating pharmacological, commercial and spiritual interest among the scientific community, government people, and different populations worldwide. The goal of this article is to report about the uses, chemistry and biological activities of ayahuasca.

Ayahuasca: Psychological and Physiologic Effects, Pharmacology and Potential Uses in Addiction and Mental Illness

Background:

Ayahuasca, a traditional Amazonian decoction with psychoactive properties, is made from bark of the Banisteriopsis caapi vine (containing beta-carboline alkaloids) and leaves of the Psychotria viridis bush (supplying the hallucinogen N,N-dimethyltryptamine, DMT). Originally used by indigenous shamans for the purposes of spirit communi-cation, magical experiences, healing, and religious rituals across several South American countries, ayahuasca has been in-corporated into folk medicine and spiritual healing, and several Brazilian churches use it routinely to foster a spiritual experi-ence. More recently, it is being used in Europe and North America, not only for religious or healing reasons, but also for rec-reation.

Objective:

To review ayahuasca’s behavioral effects, possible adverse effects, proposed mechanisms of action and potential clinical uses in mental illness.

Method:

We searched Medline, in English, using the terms ayahuasca, dimethyltryptamine, Banisteriopsis caapi, and Psy-chotria viridis and reviewed the relevant publications.

Results:

The following aspects of ayahuasca are summarized: Political and legal factors; acute and chronic psychological ef-fects; electrophysiological studies and imaging; physiological effects; safety and adverse effects; pharmacology; potential psychiatric uses.

Conclusion:

Many years of shamanic wisdom have indicated potential therapeutic uses for ayahuasca, and several present day studies suggest that it may be useful for treating various psychiatric disorders and addictions. The side effect profile ap-pears to be relatively mild, but more detailed studies need to be done. Several prominent researchers believe that government regulations with regard to ayahuasca should be relaxed so that it could be provided more readily to recognized, credible re-searchers to conduct comprehensive clinical trials.

It's Tea Time: Interference of Ayahuasca Brew on Discriminative Learning in Zebrafish

Ayahuasca is a psychoactive brew traditionally used in shamanistic and vegetalistic rituals and has recently received lot of attention due to potential cognitive benefits. Ayahuasca effects are caused by the synergistic interaction of β-carbolines (harmine, harmaline and tetrahydroarmine) contained in Banisteriopsis caapi stalks combined with the N,N-dimethyltryptamine (DMT) from Psychotria viridis leaves, a potent agonist to serotonin (5-HT) receptors. The present study approaches the effects of chronic and acute exposure to two Ayahuasca concentrations (0.1 and 0.5 ml/L) on the cognitive ability to discriminate objects in a one-trial learning task in zebrafish. Based on the combination of concentrations and exposure regimens, we divided adult zebrafish in five treatment groups: acute 0.1 and 0.5 ml/L, chronic 0.1 and 0.5 ml/L, and control 0.0 (n = 20 for each group). Then we tested them in a memory task of object discrimination. Acute Ayahuasca exposed groups performed similarly to the control group, however chronically treated fish (13 days) presented both impaired discriminative performance and locomotor alterations. Overall, these results indicate that Ayahuasca is a potent psychoactive drug that, in chronic exposure, negatively affects mnemonic parameters in zebrafish. In single exposure it does not affects cognitive performance, but the higher concentration (0.5) affected locomotion. Moreover, we reinforce the importance of the zebrafish for behavioral pharmacological studies of drug screening, in special to psychedelic drug research.

Hypothesis: The Psychedelic Ayahuasca Heals Traumatic Memories via a Sigma 1 Receptor-Mediated Epigenetic-Mnemonic Process

Ayahuasca ingestion modulates brain activity, neurotransmission, gene expression and epigenetic regulation. N,N-Dimethyltryptamine (DMT, one of the alkaloids in Ayahuasca) activates sigma 1 receptor (SIGMAR1) and others. SIGMAR1 is a multi-faceted stress-responsive receptor which promotes cell survival, neuroprotection, neuroplasticity, and neuroimmunomodulation. Simultaneously, monoamine oxidase inhibitors (MAOIs) also present in Ayahuasca prevent the degradation of DMT. One peculiarity of SIGMAR1 activation and MAOI activity is the reversal of mnemonic deficits in pre-clinical models. Since traumatic memories in post-traumatic stress disorder (PTSD) are often characterised by “repression” and PTSD patients ingesting Ayahuasca report the retrieval of such memories, it cannot be excluded that DMT-mediated SIGMAR1 activation and the concomitant MAOIs effects during Ayahuasca ingestion might mediate such “anti-amnesic” process. Here I hypothesise that Ayahuasca, via hyperactivation of trauma and emotional memory-related centres, and via its concomitant SIGMAR1- and MAOIs- induced anti-amnesic effects, facilitates the retrieval of traumatic memories, in turn making them labile (destabilised). As Ayahuasca alkaloids enhance synaptic plasticity, increase neurogenesis and boost dopaminergic neurotransmission, and those processes are involved in memory reconsolidation and fear extinction, the fear response triggered by the memory can be reprogramed and/or extinguished. Subsequently, the memory is stored with this updated significance. To date, it is unclear if new memories replace, co-exist with or bypass old ones. Although the mechanisms involved in memory are still debated, they seem to require the involvement of cellular and molecular events, such as reorganisation of homo and heteroreceptor complexes at the synapse, synaptic plasticity, and epigenetic re-modulation of gene expression. Since SIGMAR1 mobilises synaptic receptor, boosts synaptic plasticity and modulates epigenetic processes, such effects might be involved in the reported healing of traumatic memories in PTSD patients. If this theory proves to be true, Ayahuasca could come to represent the only standing pharmacological treatment which targets traumatic memories in PTSD. Lastly, since SIGMAR1 activation triggers both epigenetic and immunomodulatory programmes, the mechanism here presented could help understanding and treating other conditions in which the cellular memory is dysregulated, such as cancer, diabetes, autoimmune and neurodegenerative pathologies and substance addiction.

Behavioral Changes Over Time Following Ayahuasca Exposure in Zebrafish

The combined infusion of Banisteriopsis caapi stem and Psychotria viridis leaves, known as ayahuasca, has been used for centuries by indigenous tribes. The infusion is rich in N, N-dimethyltryptamine (DMT) and monoamine oxidase inhibitors, with properties similar to those of serotonin. Despite substantial progress in the development of new drugs to treat anxiety and depression, current treatments have several limitations. Alternative drugs, such as ayahuasca, may shed light on these disorders. Here, we present time-course behavioral changes induced by ayahuasca in zebrafish, as first step toward establishing an ideal concentration for pre-clinical evaluations. We exposed adult zebrafish to five concentrations of the ayahuasca infusion: 0 (control), 0.1, 0.5, 1, and 3 ml/L (n = 14 each group), and behavior was recorded for 60 min. We evaluated swimming speed, distance traveled, freezing and bottom dwelling every min for 60 min. Swimming speed and distance traveled decreased with an increase in ayahuasca concentration while freezing increased with 1 and 3 ml/L. Bottom dwelling increased with 1 and 3 ml/L, but declined with 0.1 ml/L. Our data suggest that small amounts of ayahuasca do not affect locomotion and reduce anxiety-like behavior in zebrafish, while increased doses of the drug lead to crescent anxiogenic effects. We conclude that the temporal analysis of zebrafish behavior is a sensitive method for the study of ayahuasca-induced functional changes in the vertebrate brain.

An ontogenic study of the behavioral effects of chronic intermittent exposure to ayahuasca in mice

Ayahuasca is a beverage obtained from decoctions of the Banisteriopsis caapi plus Psychotria viridis. In religious contexts, ayahuasca is used by different age groups. However, little is known of the effects of ayahuasca during ontogenic development, particularly with regard to the functional characteristics of the central nervous system. Animal models are useful for studying the ontogenic effects of ayahuasca because they allow exclusion of the behavioral influence associated with the ritualistic use. We investigated the effects of exposure to ayahuasca (1.5 mL/kg, orally, twice a week) on memory and anxiety in C57BL/6 mice, with the post-natal day (PND) being used as the ontogenic criterion for classification: childhood (PND21 to PND35), adolescence (PND35 to PND63), adulthood (PND90-PND118), childhood-adolescence (PND21 to PND63), childhood-adulthood (PND21 to PND118) and adolescence-adulthood (PND35 to PND118). One day after the last ayahuasca exposure, the mice were subjected to the Morris water maze (MWM), open field and elevated plus maze tasks (EPM). Ayahuasca did not affect locomotion in the open field or open arms exploration in the EPM, but increased the risk assessment behavior in the childhood group. Ayahuasca did not cause any change in acquisition of spatial reference memory in the MWM task, but decreased the time spent on the platform quadrant during the test session in the adolescence group. These results suggest that, in mice, exposure to ayahuasca in childhood and adolescence promoted anxiety and memory impairment, respectively. However, these behavioral changes were not long-lasting since they were not observed in the childhood-adulthood and adolescence-adulthood groups.

Classical hallucinogens and neuroimaging: A systematic review of human studies: Hallucinogens and neuroimaging

Serotonergic hallucinogens produce alterations of perceptions, mood, and cognition, and have anxiolytic, antidepressant, and antiaddictive properties. These drugs act as agonists of frontocortical 5-HT_2A receptors, but the neural basis of their effects are not well understood. Thus, we conducted a systematic review of neuroimaging studies analyzing the effects of serotonergic hallucinogens in man. Studies published in the PubMed, Lilacs, and SciELO databases until 12 April 2016 were included using the following keywords: "ayahuasca", "DMT", "psilocybin", "LSD", "mescaline" crossed one by one with the terms "mri", "fmri", "pet", "spect", "imaging" and "neuroimaging". Of 279 studies identified, 25 were included. Acute effects included excitation of frontolateral/frontomedial cortex, medial temporal lobe, and occipital cortex, and inhibition of the default mode network. Long-term use was associated with thinning of the posterior cingulate cortex, thickening of the anterior cingulate cortex, and decreased neocortical 5-HT_2A receptor binding. Despite the high methodological heterogeneity and the small sample sizes, the results suggest that hallucinogens increase introspection and positive mood by modulating brain activity in the fronto-temporo-parieto-occipital cortex.

Antidepressive, anxiolytic, and antiaddictive effects of ayahuasca, psilocybin and lysergic acid diethylamide (LSD): a systematic review of clinical trials published in the last 25 years

To date, pharmacological treatments for mood and anxiety disorders and for drug dependence show limited efficacy, leaving a large number of patients suffering severe and persistent symptoms. Preliminary studies in animals and humans suggest that ayahuasca, psilocybin and lysergic acid diethylamide (LSD) may have antidepressive, anxiolytic, and antiaddictive properties. Thus, we conducted a systematic review of clinical trials published from 1990 until 2015, assessing these therapeutic properties. Electronic searches were performed using the PubMed, LILACS, and SciELO databases. Only clinical trials published in peer-reviewed journals were included. Of these, 151 studies were identified, of which six met the established criteria. Reviewed studies suggest beneficial effects for treatment-resistant depression, anxiety and depression associated with life-threatening diseases, and tobacco and alcohol dependence. All drugs were well tolerated. In conclusion, ayahuasca, psilocybin and LSD may be useful pharmacological tools for the treatment of drug dependence, and anxiety and mood disorders, especially in treatment-resistant patients. These drugs may also be useful pharmacological tools to understand psychiatric disorders and to develop new therapeutic agents. However, all studies reviewed had small sample sizes, and half of them were open-label, proof-of-concept studies. Randomized, double-blind, placebo-controlled studies with more patients are needed to replicate these preliminary findings.

Effects of Long-Term Ayahuasca Administration on Memory and Anxiety in Rats

Ayahuasca is a hallucinogenic beverage that combines the action of the 5-HT2A/2C agonist N,N-dimethyltryptamine (DMT) from Psychotria viridis with the monoamine oxidase inhibitors (MAOIs) induced by beta-carbonyls from Banisteriopsis caapi. Previous investigations have highlighted the involvement of ayahuasca with the activation of brain regions known to be involved with episodic memory, contextual associations and emotional processing after ayahuasca ingestion. Moreover long term users show better performance in neuropsychological tests when tested in off-drug condition. This study evaluated the effects of long-term administration of ayahuasca on Morris water maze (MWM), fear conditioning and elevated plus maze (EPM) performance in rats. Behavior tests started 48h after the end of treatment. Freeze-dried ayahuasca doses of 120, 240 and 480 mg/kg were used, with water as the control. Long-term administration consisted of a daily oral dose for 30 days by gavage. The behavioral data indicated that long-term ayahuasca administration did not affect the performance of animals in MWM and EPM tasks. However the dose of 120 mg/kg increased the contextual conditioned fear response for both background and foreground fear conditioning. The tone conditioned response was not affected after long-term administration. In addition, the increase in the contextual fear response was maintained during the repeated sessions several weeks after training. Taken together, these data showed that long-term ayahuasca administration in rats can interfere with the contextual association of emotional events, which is in agreement with the fact that the beverage activates brain areas related to these processes.

Behavioural and neurotoxic effects of ayahuasca infusion (Banisteriopsis caapi and Psychotria viridis) in female Wistar rat

Ayahuasca, a psychoactive beverage used by indigenous and religious groups, is generally prepared by the coction of Psychotria viridis and Banisteriopsis caapi plants containing N,N-dimethyltryptamine (DMT) and β-carboline alkaloids, respectively. To investigate the acute toxicity of ayahuasca, the infusion was administered by gavage to female Wistar rats at doses of 30X and 50X the dose taken during a religious ritual, and the animals observed for 14 days. Behavioural functions were investigated one hour after dosing at 15X and 30X using the open field, elevated plus maze, and forced swimming tests. Neuronal activation (c-fos marked neurons) and toxicity (Fluoro-Jade B and Nissl/Cresyl staining) were investigated in the dorsal raphe nuclei (DRN), amygdaloid nucleus, and hippocampal formation brain areas of rats treated with a 30X ayahuasca dose. The actual lethal oral dose in female Wistar rats could not be determined in this study, but was shown to be higher than the 50X (which corresponds to 15.1mg/kg bw DMT). The ayahuasca and fluoxetine treated groups showed a significant decrease in locomotion in the open field and elevated plus-maze tests compared to controls. In the forced swimming test, ayahuasca treated animals swam more than controls, a behaviour that was not significant in the fluoxetine group. Treated animals showed higher neuronal activation in all brain areas involved in serotoninergic neurotransmission. Although this led to some brain injury, no permanent damage was detected. These results suggest that ayahuasca has antidepressant properties in Wistar female at high doses, an effect that should be further investigated.