OPEN Foundation

Publications

Serotonergic Agents That Activate 5HT2A Receptors Prevent NMDA Antagonist Neurotoxicity

Abstract

Phencyclidine, ketamine, and other agents that block NMDA glutamate receptors trigger a schizophrenia-like psychosis in humans and induce pathomorphological changes in cerebrocortical neurons in rat brain. Accumulating evidence suggests that a complex network disturbance involving multiple transmitter receptor systems is responsible for the neuronal injury, and it is proposed that a similar network disturbance is responsible for the psychotomimetic effects of NMDA antagonists, and might also be involved in the pathophysiology of schizophrenia. In the present study we present evidence that serotonergic agents possessing 5HT2A agonist activity prevent NMDA antagonist neurotoxicity in rat brain. It isproposed that 5HT2A agonists may also prevent the psychotomimetic effects of NMDA antagonists. Among the 5HT2A agonists examined and found to be neuroprotective are LSD and related hallucinogens. The apparent contradiction in proposing that these agents might have antipsychotic properties is resolved by evidence linking their hallucinogenic activity to agonist action at 5HT2C receptors, whereas antipsychotic activity would be attributable to agonist action at 5HT2A receptors.

Farber, N. B., Hanslick, J., Kirby, C., McWilliams, L., & Olney, J. W. (1998). Serotonergic Agents That Activate 5HT2A Receptors Prevent NMDA Antagonist Neurotoxicity. Neuropsychopharmacology, 18(1), 57-62. http://dx.doi.org/doi:10.1016/S0893-133X(97)00127-9

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Ketamine psychedelic therapy (KPT): a review of the results of ten years of research

Abstract

Ketamine is a prescription drug used for general anesthesia. In subanesthetic doses, it induces profound psychedelic experiences and hallucinations. The subanesthetic effect of ketamine was the hypothesized therapeutic mechanism in the authors’ use of ketamine-assisted psychotherapy for alcoholism. The results of a controlled clinical trial demonstrated a considerable increase in efficacy of the authors’ standard alcoholism treatment when supplemented by ketamine psychedelic therapy (KPT). Total abstinence for more than one year was observed in 73 out of 111 (65.8%) alcoholic patients in the KPT group, compared to 24% (24 out of 100 patients) of the conventional treatment control group (p < 0.01). The authors’ studies of the underlying psychological mechanisms of KPT have indicated that ketamine-assisted psychedelic therapy of alcoholic patients induces a harmonization of the Minnesota Multiphasic Personality Inventory (MMPI) personality profile, positive transformation of nonverbalized (mostly unconscious) self-concept and emotional attitudes to various aspects of self and other people, positive changes in life values and purposes, important insights into the meaning of life and an increase in the level of spiritual development. Most importantly, these psychological changes were shown to favor a sober lifestyle. The data from biochemical investigations showed that pharmacological action of KPT affects both monoaminergic and opioidergic neurotransmitter metabolism, i.e., those neurochemical systems which are involved in the pathogenesis of alcohol dependence. The data from EEG computer-assisted analysis demonstrated that ketamine increases theta activity in cerebrocortical regions of alcoholic patients. This is evidence of the reinforcement of limbic cortex interaction during KPT session.

Krupitsky, E. M., & Grinenko, A. Y. (1997). Ketamine psychedelic therapy (KPT): a review of the results of ten years of research. Journal of psychoactive drugs, 29(2), 165-183. https://dx.doi.org/10.1080/02791072.1997.10400185

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Positron emission tomography and fluorodeoxyglucose studies of metabolic hyperfrontality and psychopathology in the psilocybin model of psychosis

Abstract

The effects of the indolehallucinogen psilocybin, a mixed 5-HT2 and 5-HT1 agonist, on regional cerebral glucose metabolism were investigated in 10 healthy volunteers with PET and [fusion_builder_container hundred_percent=”yes” overflow=”visible”][fusion_builder_row][fusion_builder_column type=”1_1″ background_position=”left top” background_color=”” border_size=”” border_color=”” border_style=”solid” spacing=”yes” background_image=”” background_repeat=”no-repeat” padding=”” margin_top=”0px” margin_bottom=”0px” class=”” id=”” animation_type=”” animation_speed=”0.3″ animation_direction=”left” hide_on_mobile=”no” center_content=”no” min_height=”none”][F-18]-fluorodeoxyglucose (FDG) prior to and following a 15- or 20-mg dose of psilocybin.

Psychotomimetic doses of psilocybin were found to produce a global increase in cerebral metabolic rate of glucose (CMRglu) with significant and most marked increases in the frontomedial and frontolateral cortex (24.3%), anterior cingulate (24.9%), and temporomedial cortex (25.3%). Somewhat smaller increases of CMRglu were found in the basal ganglia (18.5%), and the smallest increases were found in the sensorimotor (14.7%) and occipital cortex (14.4%). The increases of CMRglu in the prefrontal cortex, anterior cingulate, temporomedial cortex, and putamen correlated positively with psychotic symptom formation, in particular with hallucinatory ego disintegration. The present data suggest that excessive 5-HT2 receptor activation results in a hyperfrontal metabolic pattern that parallels comparable metabolic findings associated with acute psychotic episodes in schizophrenics and contrasts with the hypofrontality in chronic schizophrenic patients.

Vollenweider, F. X., Leenders, K. L., Scharfetter, C., Maguire, P., Stadelmann, O., & Angst, J. (1997). Positron emission tomography and fluorodeoxyglucose studies of metabolic hyperfrontality and psychopathology in the psilocybin model of psychosis. Neuropsychopharmacology, 16(5), 357-372. http://dx.doi.org/10.1016/S0893-133X(96)00246-1
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Increased Activation of Indirect Semantic Associations under Psilocybin

Abstract

The spread of activation in semantic networks can be measured using semantic and indirect semantic priming effects in lexical decision tasks (Spitzer et al 1993a and b). For example, in thought-disordered schizophrenic patients, activation spreads faster and farther than in non-thought-disordered patients and normal subjects, which results in an increased direct and indirect semantic priming effect (see below). This has been interpreted as the result of a decreased signal-to-noise ratio in cortical neural networks that process semantic information. Such a decreased signal-to-noise ratio has been related to a decreased dopaminergic modulation (Servan-Schreiber et al. 1990; Cohen and Servan- Schreiber 1992, 1993), which we recently were able to confirm directly in a study on the effects of L-dopa on semantic and indirect semantic priming (Kischka et al 1995).

As dopamine was found to have a focusing effect on the activity in semantic networks, i.e., it increases the signal-to-noise ratio and reduces the spread of activation (measured as reduced indirect semantic priming), we set out to investigate the effect of the hallucinogenic agent psilocybin on this task. Since psilocybin is known to act on the serotonin (5-HT) system and has effects of “broadening” conscious experiences, we hypothesized that it might exert a defocusing effect on semantic networks (i.e., decrease the signal-to-noise ratio), which should lead to an increased indirect semantic priming effect.

To test this hypothesis directly, we conducted a double-blind, placebo-controlled study on the effects of psilocybin on semantic and indirect semantic priming as part of a larger project that was designed to assess the behavioral effects and pharmacokinetic properties of this hallucinogenic agent (the results will be reported elsewhere; cf. Holzmann 1995).

Spitzer, M., Thimm, M., Hermle, L., Holzmann, P., Kovar, K., Heirnann, H., … Schneider, F. (1996). Increased Activation of Indirect Semantic Associations under Psilocybin. Biological Psychiatry, 39(12),  1055–1057. http://dx.doi.org/10.1016/0006-3223(95)00418-1
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The psychopharmacology of hallucinogens.

Abstract

Hallucinogenic drugs have been inhaled, ingested, worshipped, and reviled since prehistory. With the purification and synthesis of bontanical preparations and the ensuing discovery of chemically unique agents, hope was raised regarding their therapeutic potential, but this hope has been clouded by an epidemic of abuse and an inventory of adverse effects. This review examines aspects of that controversy, including the history of hallucinogens, epidemiology of current hallucinogen abuse, the association of LSD use with prolonged psychoses and hallucinogen persisting perception disorder, and the efforts to demonstrate the drug’s therapeutic efficacy. Human subject ramifications in hallucinogen experimentation are discussed. Future lines of research are suggested in human, animal, and tissue culture paradigms.

Abraham, H. D., Aldridge, A. M., & Gogia, P. (1996). The psychopharmacology of hallucinogens. Neuropsychopharmacology, 14(4), 285-298. https://dx.doi.org/10.1016/0893-133X(95)00136-2
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Receptor binding profile suggests multiple mechanisms of action are responsible for ibogaine's putative anti-addictive activity

Abstract

The indole alkaloid ibogaine (NIH 10567, Endabuse) is currently being examined for its potential utility in the treatment of cocaine and opioid addiction. However, a clearly defined molecular mechanism of action for ibogaine’s putative anti-addictive properties has not been delineated. Radioligand binding assays targeting over 50 distinct neurotransmitter receptors, ion channels, and select second messenger systems were employed to establish a broad in vitro pharmacological profile for ibogaine. These studies revealed that ibogaine interacted with a wide variety of receptors at concentrations of 1-100 microM. These included the mu, delta, kappa, opiate, 5HT2, 5HT3, and muscarinic1 and 2 receptors, and the dopamine, norepinephrine, and serotonin uptake sites. In addition, ibogaine interacted with N-methyl-D-aspartic acid (NMDA) associated ion and sodium ion channels as determined by the inhibition of [fusion_builder_container hundred_percent=”yes” overflow=”visible”][fusion_builder_row][fusion_builder_column type=”1_1″ background_position=”left top” background_color=”” border_size=”” border_color=”” border_style=”solid” spacing=”yes” background_image=”” background_repeat=”no-repeat” padding=”” margin_top=”0px” margin_bottom=”0px” class=”” id=”” animation_type=”” animation_speed=”0.3″ animation_direction=”left” hide_on_mobile=”no” center_content=”no” min_height=”none”][3H]MK-801 and [3H]bactrachotoxin A 20-alpha-benzoate binding (BTX-B), respectively. This broad spectrum of activity may in part be responsible for ibogaine’s putative anti-addictive activity.

Sweetnam, P. M., Lancaster, J., Snowman, A., Collins, J. L., Perschke, S., Bauer, C., & Ferkany, J. (1995). Receptor binding profile suggests multiple mechanisms of action are responsible for ibogaine’s putative anti-addictive activity. Psychopharmacology, 118(4), 369-376.
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Placeboing with Psychedelics

Letter to the editor

When we consider the so-called “placebo effect,” we should realize that it is not something mysterious that merely happens on its own. It is something we do with our minds that effects our bodies. To be more accurate: we placebo. To placebo is a verb. Our minds plus our bodies do this, and like any other human activity we can speak of placeboing. When looked at this way, we can ask: How do we placebo? and Can we learn placeboing more skillfully?

A clue comes from studies of stress and emotions in the immune system. It is widely known that negative emotions and stressful life events weaken the immune system, while positive emotions and life events strengthen it. Since positive life events strengthen our immune system, here is a clue to learning to placebo.

A common healing cluster of positive feelings and thoughts accompany many instances of spontaneous remission and spiritual healing. These include feelings of exceedingly positive mood, being cared for in the hands of a loving power, dropping stress, feelings of sacredness, feeling at home in the world, among others. Thoughts include a sense of temporarily transcending one’s identity, forgiving oneself and others, overwhelming gratitude, and increased sense of reality—this is the way things really are and ought to be.

If we can reproduce this cluster, we will be on the way to learning to placebo. Various mindbody techniques including meditation, imagery, contemplative prayer, yoga, the martial arts, breathing techniques, hypnosis, and chanting all suggest a yes answer to this question, and more research to follow these apparent leads may lead to learning how to use these mindbody methods to increase our placeboing skills by strengthening our immune systems.

Do examples of extreme positive emotional states produce extreme healing? The recent flurry of articles about current research into exploring the psychotherapeutic use of psychedelics for post traumatic stress disorder, death anxiety, and other disorders show that these substances are successful when they produce states of unitive consciousness (mystical experiences) and not successful when they do not.

Lost in this discussion is that fact that mystical experiences are the most powerful emotionally positive experiences humans can have, and if normal daily positive events boost the immune system somewhat, do these strongest positive experiences boost it a great deal?

Can this spontaneous cluster of healing thoughts and feelings be recreated in a medical setting? As a 2008 Johns Hopkins study of psilocybin induced mystical experiences showed, under the right conditions and with careful screening, preparation, and professional guidance, psychedelic sessions can produce mystical experiences and a similar cluster of emotions and experiences in normal, healthy, adult volunteers. In a 14-month following up, volunteers’ comments illustrated this healing cluster:

– The utter joy and freedom of letting go—without anxiety—without direction— beyond ego self.
– The understanding that in the eyes of God—all people—were equally important and equally loved by God.
– When I confronted my shadow and yelled “What do you want?” and it disappeared in a puff smoke.

Among the other outcomes were positive mood changes, improved sense of well-being and life satisfaction, positive attitudes about life and/or self, and altruistic social effects. About two-thirds of healthy adults rated as one of the five most important spiritual experiences of their lives, including about one-third who rated them as the single most important spiritual experience of their lives. However, the researchers did not measure possible effects on the immune system.

A question on placeboing: Do overwhelmingly powerful peak experiences stimulated by psychedelics as part of professionally guided sessions boost the immune system? A possible major advance in mindbody health awaits an answer.

Roberts, T. B. (1987). Is There a Placebo Ability? Advances: Journal of the Institute for the Advancement of Health, 4(1), 5.

Differences Between the Mechanism of Action of MDMA, MBDB, and the Classic Hallucinogens. Identification of a New Therapeutic Class: Entactogens

Nichols, D. E. (1986). Differences between the mechanism of action of MDMA, MBDB, and the classic hallucinogens. Identification of a new therapeutic class: entactogens. Journal of psychoactive drugs, 18(4), 305-313. http://dx.doi.org/10.1080/02791072.1986.10472362
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Monoamine oxidase inhibitors in South American hallucinogenic plants: tryptamine and beta-carboline constituents of ayahuasca

Abstract

Ayahuasca is a hallucinogenic beverage derived by boiling the bark of the Malpighiaceous liana Banisteriopsis caapi together with the leaves of various admixture plants, viz. Psychotria viridis, Psychotria carthagenensis, or Diplopterys cabrerana. B. caapi contains harmine, harmaline, and tetrahydroharmine while the admixtures contain N,N-dimethyltryptamine (DMT). DMT, a potent hallucinogen, is inactive orally due to degradation by visceral monoamine oxidase (MAO). The β-carbolines, however, are highly active reversible inhibitors of MAO and may protect the DMT from deamination by MAO and render it orally active. This mechanism has been proposed to underlie the oral activity of ayahuasca but has not been experimentally confirmed. In the present study the constituents of the admixture plants and the alkaloids of eight ayahuasca samples from Peru were qualitatively and quantitatively analyzed using two-dimensional thin-layer chromatography (TLC), high pressure liquid chromatography (HPLC) and gas chromatography/mass spectrometry (GC/MS).

Several B. caapi cultivars were quantitatively compared for variations in alkaloid content. Three admixture plants used rarely in the manufacture of ayahuasca were also screened for alkaloids. A selected sample of β-carbolines were screened for activity as MAO inhibitors using an in vitro assay system, and structure/activity relationships were compared. Inhibition observed with single compounds was compared with the activity of selected samples of ayahuasca which were screened in the system and also with the activity of mixtures of β-carbolines. The levels of DMT and β-carbolines found in the ayahuasca samples examined in the present study were an order of magnitude greater than the levels reported in a previous study. Ayahuasca was found to be an extremely effective inhibitor of MAO in vitro and the degree of inhibition was directly correlated with the concentration of MAO-inhibiting β-carbolines. Inhibition experiments using mixtures of β-carbolines indicated that their effects in combination are additive, rather than synergistic or antagonistic. Implications of the results in understanding the pharmacology of ayahuasca are discussed.

McKenna, D. J., Towers, G. N., & Abbott, F. (1984). Monoamine oxidase inhibitors in South American hallucinogenic plants: tryptamine and β-carboline constituents of ayahuasca. Journal of ethnopharmacology, 10(2), 195-223. 10.1016/0378-8741(84)90003-5
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