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Neuroscience

Neurovascular and neuroimaging effects of the hallucinogenic serotonin receptor agonist psilocin in the rat brain.

July 17, 2015 / Mushrooms / Psilocybin, Neuroscience, Papers, Publications / By / , , , , ,

Abstract

The development of pharmacological magnetic resonance imaging (phMRI) has presented the opportunity for investigation of the neurophysiological effects of drugs in vivo. Psilocin, a hallucinogen metabolised from psilocybin, was recently reported to evoke brain region-specific, phMRI signal changes in humans. The present study investigated the effects of psilocin in a rat model using phMRI and then probed the relationship between neuronal and haemodynamic responses using a multimodal measurement preparation. Psilocin (2 mg/kg or 0.03 mg/kg i.v.) or vehicle was administered to rats (N = 6/group) during either phMRI scanning or concurrent imaging of cortical blood flow and recording of local field potentials. Compared to vehicle controls psilocin (2 mg/kg) evoked phMRI signal increases in a number of regions including olfactory and limbic areas and elements of the visual system. PhMRI signal decreases were seen in other regions including somatosensory and motor cortices. Investigation of neurovascular coupling revealed that whilst neuronal responses (local field potentials) to sensory stimuli were decreased in amplitude by psilocin administration, concurrently measured haemodynamic responses (cerebral blood flow) were enhanced. The present findings show that psilocin evoked region-specific changes in phMRI signals in the rat, confirming recent human data. However, the results also suggest that the haemodynamic signal changes underlying phMRI responses reflect changes in both neuronal activity and neurovascular coupling. This highlights the importance of understanding the neurovascular effects of pharmacological manipulations for interpreting haemodynamic neuroimaging data.

Spain, A., Howarth, C., Khrapitchev, A., Sharp, T., Sibson, N. R., & Martin, C. (2015). Neurovascular and neuroimaging effects of the hallucinogenic serotonin receptor agonist psilocin in the rat brain. Neuropharmacology. https://dx.doi.org/10.1016/j.neuropharm.2015.07.018
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Ketamine induces anxiolytic effects in adult zebrafish: A multivariate statistics approach.

July 14, 2015 / Anxiety Disorders / PTSD, Ketamine, Neuroscience, Papers, Psychology, Publications / By / , ,

Abstract

Ketamine inappropriate use has been associated with serious consequences for human health. Anesthetic properties of ketamine are well-known but its side effects are poorly described, including the effects on anxiety. In this context, animal models are a safe way to conduct this neurobehavioral research and zebrafish (Danio rerio) is an interesting model which has several advantages. The validation and interpretation of results of behavioral assays requires a suitable statistical approach and the use of multivariate statistical methods has been little explored, especially in zebrafish behavioral models. Here, we investigated the anxiolytic-induced effects of ketamine in adult zebrafish, using Light-Dark Test and Multivariate Statistics methods (PCA, HCA and SIMCA). In addition, we compared the processing of data to the one carried out by analysis of variance (ANOVA) Ketamine produced significant concentration of exposure-dependent anxiolytic effects, increasing time in white area and number of crossings and decreasing latency to first access to white area. Average entry duration behavior resulted in a slight decrease from control to treatment groups, with an observed concentration-dependent increase among the exposed groups. PCA results indicated that two principal components represent 88.74% of all the system information. HCA and PCA results showed a higher similarity among control and treatment groups exposed to lower concentrations of ketamine and among treatment groups exposed to concentrations of 40 and 60 mg.L-1. In SIMCA results, interclasses distances were concentration of exposure-dependent increased and misclassifications and interclasses residues results also support these findings. These findings confirm the anxiolytic potential of ketamine and zebrafish sensibility to this drug. In summary, our study confirms that zebrafish and multivariate statistics data validation is an appropriate and viable behavioral model for the study of psychoactive substances, providing a detailed and reliable analysis.

De Campos, E. G., Bruni, A. T., & De Martinis, B. S. (2015). Ketamine induces anxiolytic effects in adult zebrafish: A multivariate statistics approach. Behavioural Brain Research.  https://dx.doi.org/10.1016/j.bbr.2015.07.017
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Psychedelics and Immunomodulation: Novel Approaches and Therapeutic Opportunities

July 14, 2015 / DMT, LSD, MDMA, Neuroscience, Papers, Psychiatry & Medicine, Psychology, Publications / By /

Abstract

Classical psychedelics are psychoactive substances, which, besides their psychopharmacological activity, have also been shown to exert significant modulatory effects on immune responses by altering signaling pathways involved in inflammation, cellular proliferation, and cell survival via activating NF-κB and mitogen-activated protein kinases. Recently, several neurotransmitter receptors involved in the pharmacology of psychedelics, such as serotonin and sigma-1 receptors, have also been shown to play crucial roles in numerous immunological processes. This emerging field also offers promising treatment modalities in the therapy of various diseases including autoimmune and chronic inflammatory conditions, infections, and cancer. However, the scarcity of available review literature renders the topic unclear and obscure, mostly posing psychedelics as illicit drugs of abuse and not as physiologically relevant molecules or as possible agents of future pharmacotherapies. In this paper, the immunomodulatory potential of classical serotonergic psychedelics, including N,N-dimethyltryptamine (DMT), 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT), lysergic acid diethylamide (LSD), 2,5-dimethoxy-4-iodoamphetamine, and 3,4-methylenedioxy-methamphetamine will be discussed from a perspective of molecular immunology and pharmacology. Special attention will be given to the functional interaction of serotonin and sigma-1 receptors and their cross-talk with toll-like and RIG-I-like pattern-recognition receptor-mediated signaling. Furthermore, novel approaches will be suggested feasible for the treatment of diseases with chronic inflammatory etiology and pathology, such as atherosclerosis, rheumatoid arthritis, multiple sclerosis, schizophrenia, depression, and Alzheimer’s disease.

Szabo, A. Psychedelics and immunomodulation: Novel approaches and therapeutic opportunities. Frontiers in Immunology, 0. https://dx.doi.org/10.3389/fimmu.2015.00358
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Towards new mechanisms: an update on therapeutics for treatment-resistant major depressive disorder

July 7, 2015 / Depressive Disorders, Neuroscience, Papers, Psychology, Publications / By / ,

Abstract

Depression is a devastating disorder that places a significant burden on both the individual and society. As such, the discovery of novel therapeutics and innovative treatments—especially for treatment-resistant depression (TRD)—are essential. Research into antidepressant therapies for TRD has evolved from explorations of antidepressants with primary mechanisms of action on the monoaminergic neurotransmitter system to augmentation agents with primary mechanisms both within and outside of the serotonin/norepinephrine system. Now the field of antidepressant research has changed trajectories yet again; this time, compounds with primary mechanisms of action on the glutamatergic, cholinergic and opioid systems are in the forefront of antidepressant exploration. In this review, we will discuss the most recent research surrounding these novel compounds. In addition, we will discuss novel device-based therapeutics, with a particular focus on transcranial magnetic stimulation. In many cases of antidepressant drug discovery, the role of serendipity coupled with meticulous clinical observation in drug development in medicine was crucial. Moving forward, we must look toward the combination of innovation plus improvements on the remarkable discoveries thus far to advance the field of antidepressant research.

Papakostas, G. I., & Ionescu, D. F. (2015). Towards new mechanisms: an update on therapeutics for treatment-resistant major depressive disorder. Molecular psychiatry. https://dx.doi.org/10.1038/mp.2015.92
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Perceptual distortions and delusional thinking following ketamine administration are related to increased pharmacological MRI signal changes in the parietal lobe

July 6, 2015 / Ketamine, Neuroscience, Papers, Psychology, Psychotic Disorders, Publications / By / , , , , ,

Abstract

Ketamine produces effects in healthy humans that resemble the positive, negative and cognitive symptoms of schizophrenia. We investigated the effect of ketamine administration on brain activity as indexed by blood-oxygen-level-dependent (BOLD) signal change response, and its relationship to ketamine-induced subjective changes, including perceptual distortion. Thirteen healthy participants volunteered for the study. All underwent a 15-min functional MRI acquisition with a ketamine infusion commencing after 5 min (approx 0.26 mg/kg over 20s followed by an infusion of approx. 0.42 mg/kg/h). Following the scan, participants self-rated ketamine-induced effects using the Psychotomimetic States Inventory. Ketamine led to widespread cortical and subcortical increases in BOLD response (FWE-corrected p < 0.01). Self-rated perceptual distortions and delusional thoughts correlated with increased BOLD response in the paracentral lobule (FWE-corrected p < 0.01). The findings suggest that BOLD increases in parietal cortices reflect ketamine effects on circuits that contribute to its capacity to produce perceptual alterations and delusional interpretations.

Stone, J., Kotoula, V., Dietrich, C., De Simoni, S., Krystal, J. H., & Mehta, M. A. (2015). Perceptual distortions and delusional thinking following ketamine administration are related to increased pharmacological MRI signal changes in the parietal lobe. Journal of Psychopharmacology, 0269881115592337. https://dx.doi.org/10.1177/0269881115592337
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Pharmacokinetics and concentration-effect relationship of oral LSD in humans

June 24, 2015 / LSD, Neuroscience, Papers, Psychiatry & Medicine, Publications / By / , , , ,

Abstract

Background: The pharmacokinetics of oral lysergic acid diethylamide (LSD) are unknown, despite its common recreational use and renewed interest in its use in psychiatric research and practice.

Methods: We characterized the pharmacokinetic profile, pharmacokinetic-pharmacodynamic relationship, and urine recovery of LSD and its main metabolite after administration of a single oral dose of LSD (200 μg) in eight male and eight female healthy subjects.

Results: Plasma LSD concentrations were quantifiable (> 0.1 ng/ml) in all of the subjects up to 12 h after administration. Maximal concentrations of LSD (mean ± SD: 4.5 ± 1.4 ng/ml) were reached (median, range) 1.57 (0.5-4) h after administration. Concentrations then decreased following first-order kinetics with a half-life of 3.6 ± 0.9 h up to 12 h and slower elimination thereafter with a terminal half-life of 8.9 ± 5.9 h. One percent of the orally administered LSD was eliminated in urine as LSD, and 14% was eliminated as 2-oxo-3-hydroxy-LSD within 24 h. No sex differences were observed in the pharmacokinetic profiles of LSD. The acute subjective and sympathomimetic responses to LSD lasted up to 12 h and were closely associated with the concentrations in plasma over time and exhibited no acute tolerance.

Conclusions: These first data on the pharmacokinetics and concentration-effect relationship of oral LSD are relevant for further clinical studies and serve as a reference for the assessment of intoxication with LSD.

Dolder, P. C., Schmid, Y., Haschke, M., Rentsch, K. M., & Liechti, M. E. (2015). Pharmacokinetics and concentration-effect relationship of oral LSD in humans. International Journal of Neuropsychopharmacology, pyv072.

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Ketamine and Phencyclidine: the good, the bad and the unexpected

June 15, 2015 / Humanities & Art, Ketamine, Neuroscience, Papers, Psychology, Publications / By / ,

Abstract

The history of ketamine and phencyclidine from their development as potential clinical anaesthetics, through drugs of abuse and animal models of schizophrenia to potential rapidly acting antidepressants is reviewed. The discovery in 1983 of the NMDA receptor antagonist property of ketamine and phencyclidine was a key step to understanding their pharmacology, including their psychotomimetic effects in man. This review describes the historical context and the course of that discovery and its expansion into other hallucinatory drugs. The relevance of these findings to modern hypotheses of schizophrenia and the implications for drug discovery are reviewed. The finding of the rapidly acting antidepressant effects of ketamine in man are discussed in relation to other glutamatergic mechanisms.

Lodge, D., & Mercier, M. S. (2015). Ketamine and Phencyclidine: the good, the bad and the unexpected. British journal of pharmacology.  https://dx.doi.org/10.1111/bph.13222
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Restructuring consciousness -the psychedelic state in light of integrated information theory

June 12, 2015 / LSD, Mushrooms / Psilocybin, Neuroscience, Papers, Publications / By /

Abstract

The psychological state elicited by the classic psychedelics drugs, such as LSD and psilocybin, is one of the most fascinating and yet least understood states of consciousness. However, with the advent of modern functional neuroimaging techniques, the effect of these drugs on neural activity is now being revealed, although many of the varied phenomenological features of the psychedelic state remain challenging to explain. Integrated information theory (IIT) is one of the foremost contemporary theories of consciousness, providing a mathematical formalization of both the quantity and quality of conscious experience. This theory can be applied to all known states of consciousness, including the psychedelic state. Using the results of functional neuroimaging data on the psychedelic state, the effects of psychedelic drugs on both the level and structure of consciousness can be explained in terms of the conceptual framework of IIT. This new IIT-based model of the psychedelic state provides an explanation for many of its phenomenological features, including unconstrained cognition, alterations in the structure and meaning of concepts and a sense of expanded awareness. This model also suggests that whilst cognitive flexibility, creativity, and imagination are enhanced during the psychedelic state, this occurs at the expense of cause-effect information, as well as degrading the brain’s ability to organize, categorize, and differentiate the constituents of conscious experience. Furthermore, the model generates specific predictions that can be tested using a combination of functional imaging techniques, as has been applied to the study of levels of consciousness during anesthesia and following brain injury.

Gallimore, A. R. (2015). Restructuring Consciousness–the Psychedelic State in Light of Integrated Information Theory. Name: Frontiers in Human Neuroscience, 9, 346. https://dx.doi.org/10.3389/fnhum.2015.00346
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Chronic MDMA induces neurochemical changes in the hippocampus of adolescent and young adult rats: Down-regulation of apoptotic markers

June 9, 2015 / MDMA, Neuroscience, Papers, Publications / By / ,

Abstract

While hippocampus is a brain region particularly susceptible to the effects of MDMA, the cellular and molecular changes induced by MDMA are still to be fully elucidated, being the dosage regimen, the species and the developmental stage under study great variables. This study compared the effects of one and four days of MDMA administration following a binge paradigm (3×5 mg/kg, i.p., every 2 h) on inducing hippocampal neurochemical changes in adolescent (PND 37) and young adult (PND 58) rats. The results showed that chronic MDMA caused hippocampal protein deficits in adolescent and young adult rats at different levels: (1) impaired serotonergic (5-HT2A and 5-HT2C post-synaptic receptors) and GABAergic (GAD2 enzyme) signaling, and (2) decreased structural cytoskeletal neurofilament proteins (NF-H, NF-M and NF-L). Interestingly, these effects were not accompanied by an increase in apoptotic markers. In fact, chronic MDMA inhibited proteins of the apoptotic pathway (i.e., pro-apoptotic FADD, Bax and cytochrome c) leading to an inhibition of cell death markers (i.e., p-JNK1/2, cleavage of PARP-1) and suggesting regulatory mechanisms in response to the neurochemical changes caused by the drug. The data, together with the observed lack of GFAP activation, support the view that chronic MDMA effects, regardless of the rat developmental age, extends beyond neurotransmitter systems to impair other hippocampal structural cell markers. Interestingly, inhibitory changes in proteins from the apoptotic pathway might be taking place to overcome the protein deficits caused by MDMA.

García-Cabrerizo, R., & García-Fuster, M. J. (2015). Chronic MDMA induces neurochemical changes in the hippocampus of adolescent and young adult rats: Down-regulation of apoptotic markers. Neurotoxicology, 49, 104-113. http://dx.doi.org/10.1016/j.neuro.2015.06.001

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Antidepressant drug action – From rapid changes on network function to network rewiring

June 9, 2015 / Depressive Disorders, Ketamine, Neuroscience, Papers, Psychology, Publications / By / ,

Abstract

There has been significant recent progress in understanding the neurobiological mechanisms of antidepressant treatments. The delayed-onset of action of monoamine-based antidepressant drugs have been linked to their ability to slowly increase synaptic plasticity and neuronal excitability via altering neurotrophic signaling (synthesis of BDNF and activation of its receptor TrkB), dematuration of GABAergic interneurons and inhibition of “breaks of plasticity”. On the other hand, antidepressants rapidly regulate emotional processing that – with the help of heightened plasticity and appropriate rehabilitation – gradually lead to significant changes on functional neuronal connectivity and clinical recovery. Moreover, the discovery of rapid-acting antidepressants, most notably ketamine, has inspired renewed interest for novel antidepressant developments with better efficacy and faster onset of action. Therapeutic effects of rapid-acting antidepressants have been linked with their ability to rapidly regulate neuronal excitability and thereby increase synaptic translation and release of BDNF, activation of the TrkB-mTOR-p70S6k signaling pathway and increased synaptogenesis within the prefrontal cortex. Thus, alterations in TrkB signaling, synaptic plasticity and neuronal excitability are shared neurobiological phenomena implicated in antidepressant responses produced by both gradually and rapid acting antidepressants. However, regardless of antidepressant, their therapeutic effects are not permanent which suggests that their effects on neuronal connectivity and network function remain unstable and vulnerable for psychosocial challenges.

Rantamäki, T., & Yalcin, I. (2015). Antidepressant drug action–from rapid changes on network function to network rewiring. Progress in Neuro-Psychopharmacology and Biological Psychiatry. https://dx.doi.org/10.1016/j.pnpbp.2015.06.001
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