OPEN Foundation

Menu

Author name: OPEN Foundation

Ketamine decreases sensitivity of male rats to misleading negative feedback in a probabilistic reversal-learning task

/ Depressive Disorders, Ketamine, Papers, Psychology, Publications / / , ,

Abstract

RATIONALE: Depression is characterized by an excessive attribution of value to negative feedback. This imbalance in feedback sensitivity can be measured using the probabilistic reversal-learning (PRL) task. This task was initially designed for clinical research, but introduction of its rodent version provides a new and much needed translational paradigm to evaluate potential novel antidepressants.

OBJECTIVES: In the present study, we aimed at evaluating the effects of a compound showing clear antidepressant properties-ketamine (KET)-on the sensitivity of rats to positive and negative feedback in the PRL paradigm.

METHODS: We trained healthy rats in an operant version of the PRL task. For successful completion of the task, subjects had to learn to ignore infrequent and misleading feedback, arising from the probabilistic (80:20) nature of the discrimination. Subsequently, we evaluated the effect of KET (5, 10, and 20 mg/kg) on feedback sensitivity 1, 24, and 48 h after administration.

RESULTS: We report that acute administration of the highest dose of KET (20 mg/kg) rapidly and persistently decreases the proportion of lose-shift responses made by rats after receiving negative feedback.

CONCLUSION: Present results suggest that KET decreases negative feedback sensitivity and that changes in this basic neurocognitive function might be one of the factors responsible for its antidepressant action.

Rychlik, M., Bollen, E., & Rygula, R. (2016). Ketamine decreases sensitivity of male rats to misleading negative feedback in a probabilistic reversal-learning task. Psychopharmacology, 1-8. 10.1007/s00213-016-4497-1
Link to full text

Ketamine decreases sensitivity of male rats to misleading negative feedback in a probabilistic reversal-learning task Read More »

Metabolism of psilocybin and psilocin: clinical and forensic toxicological relevance

/ Mushrooms / Psilocybin, Papers, Pharmacology & Chemistry, Publications / /

Abstract

Psilocybin and psilocin are controlled substances in many countries. These are the two main hallucinogenic compounds of the “magic mushrooms” and both act as agonists or partial agonists at 5-hydroxytryptamine (5-HT)2A subtype receptors. During the last few years, psilocybin and psilocin have gained therapeutic relevance but considerable physiological variability between individuals that can influence dose-response and toxicological profile has been reported. This review aims to discuss metabolism of psilocybin and psilocin, by presenting all major and minor psychoactive metabolites. Psilocybin is primarily a pro-drug that is dephosphorylated by alkaline phosphatase to active metabolite psilocin. This last is then further metabolized, psilocin-O-glucuronide being the main urinary metabolite with clinical and forensic relevance in diagnosis.

Dinis-Oliveira, R. J. (2016). METABOLISM OF PSILOCYBIN AND PSILOCIN: CLINICAL AND FORENSIC TOXICOLOGICAL RELEVANCE. Drug Metabolism Reviews, (just-accepted), 1-21. 10.1080/03602532.2016.1278228
Link to full text

Metabolism of psilocybin and psilocin: clinical and forensic toxicological relevance Read More »

“Being with a Buddha”: A Case Report of Methoxetamine Use in a United States Veteran with PTSD

/ Anxiety Disorders / PTSD, Ketamine, Papers, Psychology / / , ,

Abstract

Methoxetamine (MXE) is a ketamine analogue with a high affinity for the N-methyl-D-aspartate (NMDA) receptor. MXE is a newly emerging designer drug of abuse and is widely available through on-line sources and is not detected by routine urine drug screens. In this report, we describe a United States (US) veteran with posttraumatic stress disorder (PTSD) and heavy polysubstance use, who injected high dose MXE for its calming effect. Given MXE’s structural similarities to ketamine and recent work showing that ketamine reduces PTSD symptoms, we hypothesize that MXE alleviated this veteran’s PTSD symptoms through action at the NMDA receptor and via influences on brain-derived neurotrophic factor (BDNF). To our knowledge, this is the first case report of self-reported use of MXE in the US veteran population. More awareness of designer drugs, such as MXE, is an important first step in engaging patients in the treatment of designer drug addiction in both military/veteran settings and civilian settings.
Striebel, J. M., Nelson, E. E., & Kalapatapu, R. K. (2017). “Being with a Buddha”: A Case Report of Methoxetamine Use in a United States Veteran with PTSD. Case reports in psychiatry, 2017. 10.1155/2017/2319094
Link to full text

“Being with a Buddha”: A Case Report of Methoxetamine Use in a United States Veteran with PTSD Read More »

"Being with a Buddha": A Case Report of Methoxetamine Use in a United States Veteran with PTSD

/ Anxiety Disorders / PTSD, Ketamine, Papers, Psychology / / , ,

Abstract

Methoxetamine (MXE) is a ketamine analogue with a high affinity for the N-methyl-D-aspartate (NMDA) receptor. MXE is a newly emerging designer drug of abuse and is widely available through on-line sources and is not detected by routine urine drug screens. In this report, we describe a United States (US) veteran with posttraumatic stress disorder (PTSD) and heavy polysubstance use, who injected high dose MXE for its calming effect. Given MXE’s structural similarities to ketamine and recent work showing that ketamine reduces PTSD symptoms, we hypothesize that MXE alleviated this veteran’s PTSD symptoms through action at the NMDA receptor and via influences on brain-derived neurotrophic factor (BDNF). To our knowledge, this is the first case report of self-reported use of MXE in the US veteran population. More awareness of designer drugs, such as MXE, is an important first step in engaging patients in the treatment of designer drug addiction in both military/veteran settings and civilian settings.
Striebel, J. M., Nelson, E. E., & Kalapatapu, R. K. (2017). “Being with a Buddha”: A Case Report of Methoxetamine Use in a United States Veteran with PTSD. Case reports in psychiatry, 2017. 10.1155/2017/2319094
Link to full text

"Being with a Buddha": A Case Report of Methoxetamine Use in a United States Veteran with PTSD Read More »

Prophylactic Ketamine Attenuates Learned Fear

/ Anxiety Disorders / PTSD, Depressive Disorders, Ketamine, Neuroscience, Papers, Psychology, Publications / / , , , , , ,

Abstract

Ketamine has been reported to be an efficacious antidepressant for major depressive disorder (MDD) and posttraumatic stress disorder (PTSD). Most recently, ketamine has also been shown to be prophylactic against stress-induced depressive-like behavior in mice. It remains unknown, however, when ketamine should be administered relative to a stressor in order to maximize its antidepressant and/or prophylactic effects. Moreover, it is unknown if ketamine can be prophylactic against subsequent stressors. We systematically administered ketamine at different time points relative to a fear experience in order to determine when ketamine is most effective at reducing fear expression or preventing fear reactivation. Using a contextual fear conditioning (CFC) paradigm, mice were administered a single dose of saline or ketamine (30 mg kg−1) at varying time points before or after CFC. Mice administered prophylactic ketamine 1 week, but not 1 month or 1 h before CFC, exhibited reduced freezing behavior when compared with mice administered saline. In contrast, ketamine administration following CFC or during extinction did not alter subsequent fear expression. However, ketamine administered before reinstatement increased the number of rearing bouts in an open field, possibly suggesting an increase in attentiveness. These data indicate that ketamine can buffer a fear response when given a week before as prophylactic, but not when given immediately before or after a stress-inducing episode. Thus, ketamine may be most useful in the clinic if administered in a prophylactic fashion 1 week before a stressor in order to protect against heightened fear responses to aversive stimuli.

McGowan, J. C., LaGamma, C. T., Lim, S. C., Tsitsiklis, M., Neria, Y., Brachman, R. A., & Denny, C. A. (2017). Prophylactic Ketamine Attenuates Learned Fear. Neuropsychopharmacology. 10.1038/npp.2017.19
Link to full text

Prophylactic Ketamine Attenuates Learned Fear Read More »

Rapid antidepressant effects of the psychedelic ayahuasca in treatment-resistant depression: a randomised placebo-controlled trial

/ Ayahuasca, Depressive Disorders, Papers, Psychology, Publications / / , , , , , ,

Abstract

Major Depressive Disorder affects about 350 million people worldwide, and about one-third of the patients are considered treatment-resistant. Furthermore, available antidepressants take usually two weeks for the onset of their antidepressant effect. Recent open label trials show that psychedelics, such as ayahuasca and psilocybin, hold promise as fast-onset antidepressants. Although promising, these studies were not controlled for the placebo effect. To address this issue, and to further test the antidepressant effects of ayahuasca, we conducted a parallel arm, double blind randomised placebo-controlled trial, in patients with treatment-resistant major depression. Thirty-five patients with treatment-resistant major depression received a single dose of ayahuasca or placebo. We measured as primary outcome the change in the Hamilton Depression Rating scale (HAM-D) seven days after the dosing session, and as secondary outcomes the changes in Montgomery-Asberg Depression Rating Scale (MADRS), and response rates at one day (D1), two days (D2) and seven days (D7) after dosing, and remission rates at D7. This study is registered with http://clinicaltrials.gov (NCT02914769). We observed robust evidence of rapid antidepressant effects of a single dosing session with ayahuasca when compared to placebo. HAM-D scores at D7 were significantly lower in patients treated with ayahuasca than in those treated with placebo (p=0.019; Cohen’s d=0.98). MADRS scores were significantly reduced in the ayahuasca group compared to the placebo group at all endpoints (at D1 and D2, p=0.04; at D7, p<0.0001). Between-group effect sizes increased from D1 to D7 (D1: Cohen’s d=0.84; D2: Cohen’s d=0.84; D7: Cohen’s d=1.49). Response rates were high for both groups at D1 and D2, and were significantly higher in the ayahuasca group only at D7 (64% vs. 27%; OR = 4.95; p = 0.04; NNT = 2.66). Remission rate was not significantly different between groups. Our study provides new evidence of rapid antidepressant effects of ayahuasca for treatment-resistant major depression.

Palhano-Fontes, F., Barreto, D., Onias, H., Andrade, K. C., Novaes, M., Pessoa, J., … & Tofoli, L. (2017). Rapid antidepressant effects of the psychedelic ayahuasca in treatment-resistant depression: a randomised placebo-controlled trial. bioRxiv, 103531. 10.1101/103531
Link to full text

Rapid antidepressant effects of the psychedelic ayahuasca in treatment-resistant depression: a randomised placebo-controlled trial Read More »

A Receptor on Acid

/ LSD, Neuroscience, Papers, Psychology, Publications / / ,

Abstract

Wacker et al. report the crystal structure of LSD in complex with one of its major targets in the brain, the 5-HT2B receptor, the first such structure for any psychedelic drug. The results shed light on the molecular mechanisms underlying its ability to induce hallucinations with greater duration and potency than closely related compounds.
Chen, Q., & Tesmer, J. J. (2017). A receptor on acid. Cell, 168(3), 339-341. 10.1016/j.cell.2017.01.012
Link to full text

A Receptor on Acid Read More »

Crystal Structure of an LSD-Bound Human Serotonin Receptor

/ LSD, Neuroscience, Papers, Publications / / , , , , , ,

Abstract

The prototypical hallucinogen LSD acts via serotonin receptors, and here we describe the crystal structure of LSD in complex with the human serotonin receptor 5-HT2B. The complex reveals conformational rearrangements to accommodate LSD, providing a structural explanation for the conformational selectivity of LSD’s key diethylamide moiety. LSD dissociates exceptionally slow from both 5-HT2BR and 5-HT2AR—a major target for its psychoactivity. Molecular dynamics (MD) simulations suggest that LSD’s slow binding kinetics may be due to a “lid” formed by extracellular loop 2 (EL2) at the entrance to the binding pocket. A mutation predicted to increase the mobility of this lid greatly accelerates LSD’s binding kinetics and selectively dampens LSD-mediated β-arrestin2 recruitment. This study thus reveals an unexpected binding mode of LSD; illuminates key features of its kinetics, stereochemistry, and signaling; and provides a molecular explanation for LSD’s actions at human serotonin receptors.

Wacker, D., Wang, S., McCorvy, J. D., Betz, R. M., Venkatakrishnan, A. J., Levit, A., … & Shoichet, B. K. (2017). Crystal Structure of an LSD-Bound Human Serotonin Receptor. Cell, 168(3), 377-389. 10.1016/j.cell.2016.12.033
Link to full text

Crystal Structure of an LSD-Bound Human Serotonin Receptor Read More »

The factor structure of the Mystical Experience Questionnaire (MEQ): Reply to Bouso et al., 2016

/ Mushrooms / Psilocybin, Papers, Psychology, Publications / / ,

Barrett, F. S., & Griffiths, R. R. (2017). The factor structure of the Mystical Experience Questionnaire (MEQ): Reply to Bouso et al., 2016. Human Psychopharmacology: Clinical and Experimental, 32(1). 10.1002/hup.2564
Link to full text

The factor structure of the Mystical Experience Questionnaire (MEQ): Reply to Bouso et al., 2016 Read More »

The factor structure of the Mystical Experience Questionnaire (MEQ): Reply to Barrett & Griffiths (2016)

/ Mushrooms / Psilocybin, Papers, Psychology, Publications / / , , ,

Bouso, J. C., Pedrero‐Pérez, E. J., Gandy, S., & Alcázar‐Córcoles, M. Á. (2017). The factor structure of the Mystical Experience Questionnaire (MEQ): Reply to Barrett & Griffiths (2016). Human Psychopharmacology: Clinical and Experimental, 32(1). 10.1002/hup.2570
Link to full text

The factor structure of the Mystical Experience Questionnaire (MEQ): Reply to Barrett & Griffiths (2016) Read More »

Journal Club #22: Applying the EU Regulatory Framework to Determine the Benefit–Risk Profile of Psychedelics - March 3

REGISTER NOW