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M. Young

Separating the agony from ecstasy: R(-)-3,4-methylenedioxymethamphetamine has prosocial and therapeutic-like effects without signs of neurotoxicity in mice

October 6, 2017 / Anxiety Disorders / PTSD, MDMA, Papers, Psychology, Publications / By / , , , ,

Abstract

S,R(+/-)-3,4-methylenedioxymethamphetamine (SR-MDMA) is an amphetamine derivative with prosocial and putative therapeutic effects. Ongoing clinical trials are investigating it as a treatment for post-traumatic stress disorder (PTSD) and other conditions. However, its potential for adverse effects such as hyperthermia and neurotoxicity may limit its clinical viability. We investigated the hypothesis that one of the two enantiomers of SR-MDMA, R-MDMA, would retain the prosocial and therapeutic effects but with fewer adverse effects. Using male Swiss Webster and C57BL/6 mice, the prosocial effects of R-MDMA were measured using a social interaction test, and the therapeutic-like effects were assessed using a Pavlovian fear conditioning and extinction paradigm relevant to PTSD. Locomotor activity and body temperature were tracked after administration, and neurotoxicity was evaluated post-mortem. R-MDMA significantly increased murine social interaction and facilitated extinction of conditioned freezing. Yet, unlike racemic MDMA, it did not increase locomotor activity, produce signs of neurotoxicity, or increase body temperature. A key pharmacological difference between R-MDMA and racemic MDMA is that R-MDMA has much lower potency as a dopamine releaser. Pretreatment with a selective dopamine D1 receptor antagonist prevented SR-MDMA-induced hyperthermia, suggesting that differential dopamine signaling may explain some of the observed differences between the treatments. Together, these results indicate that the prosocial and therapeutic effects of SR-MDMA may be separable from the stimulant, thermogenic, and potential neurotoxic effects. To what extent these findings translate to humans will require further investigation, but these data suggest that R-MDMA could be a more viable therapeutic option for the treatment of PTSD and other disorders for which SR-MDMA is currently being investigated.
Curry, D. W., Young, M. B., Tran, A. N., Daoud, G. E., & Howell, L. L. (2018). Separating the agony from ecstasy: R (–)-3, 4-methylenedioxymethamphetamine has prosocial and therapeutic-like effects without signs of neurotoxicity in mice. Neuropharmacology, 128, 196-206. 10.1016/j.neuropharm.2017.10.003
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Inhibition of serotonin transporters disrupts the enhancement of fear memory extinction by 3,4-methylenedioxymethamphetamine (MDMA)

July 24, 2017 / Anxiety Disorders / PTSD, MDMA, Neuroscience, Papers, Psychology / By / , , , , , ,

Abstract

Rationale

3,4-Methylenedioxymethamphetamine (MDMA) persistently improves symptoms of post-traumatic stress disorder (PTSD) when combined with psychotherapy. Studies in rodents suggest that these effects can be attributed to enhancement of fear memory extinction. Therefore, MDMA may improve the effects of exposure-based therapy for PTSD, particularly in treatment-resistant patients. However, given MDMA’s broad pharmacological profile, further investigation is warranted before moving to a complex clinical population.

Objectives

We aimed to inform clinical research by providing a translational model of MDMA’s effect, and elucidating monoaminergic mechanisms through which MDMA enhances fear extinction.

Methods

We explored the importance of monoamine transporters targeted by MDMA to fear memory extinction, as measured by reductions in conditioned freezing and fear-potentiated startle (FPS) in mice. Mice were treated with selective inhibitors of individual monoamine transporters prior to combined MDMA treatment and fear extinction training.

Results

MDMA enhanced the lasting extinction of FPS. Acute and chronic treatment with a 5-HT transporter (5-HTT) inhibitor blocked MDMA’s effect on fear memory extinction. Acute inhibition of dopamine (DA) and norepinephrine (NE) transporters had no effect. 5-HT release alone did not enhance extinction. Blockade of MDMA’s effect by 5-HTT inhibition also downregulated 5-HT2A-mediated behavior, and 5-HT2A antagonism disrupted MDMA’s effect on extinction.

Conclusions

We validate enhancement of fear memory extinction by MDMA in a translational behavioral model, and reveal the importance of 5-HTT and 5-HT2A receptors to this effect. These observations support future clinical research of MDMA as an adjunct to exposure therapy, and provide important pharmacological considerations for clinical use in a population frequently treated with 5-HTT inhibitors.

Young, M. B., Norrholm, S. D., Khoury, L. M., Jovanovic, T., Rauch, S. A., Reiff, C. M., … & Howell, L. L. (2017). Inhibition of serotonin transporters disrupts the enhancement of fear memory extinction by 3, 4-methylenedioxymethamphetamine (MDMA). Psychopharmacology, 234(19), 2883-2895. 10.1007/s00213-017-4684-8
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3,4-Methylenedioxymethamphetamine facilitates fear extinction learning

September 15, 2015 / Anxiety Disorders / PTSD, MDMA, Neuroscience, Papers, Psychology, Publications / By / , , ,

Abstract

Acutely administered 3,4-methylenedioxymethamphetamine (MDMA, ‘ecstasy’) has been proposed to have long-term positive effects on post-traumatic stress disorder (PTSD) symptoms when combined with psychotherapy. No preclinical data support a mechanistic basis for these claims. Given the persistent nature of psychotherapeutic gains facilitated by MDMA, we hypothesized that MDMA improves fear extinction learning, a key process in exposure-based therapies for PTSD. In these experiments, mice were first exposed to cued fear conditioning and treated with drug vehicle or MDMA before extinction training 2 days later. MDMA was administered systemically and also directly targeted to brain structures known to contribute to extinction. In addition to behavioral measures of extinction, changes in mRNA levels of brain-derived neurotrophic factor (Bdnf) and Fos were measured after MDMA treatment and extinction. MDMA (7.8 mg kg−1) persistently and robustly enhanced long-term extinction when administered before extinction training. MDMA increased the expression of Fos in the amygdala and medial prefrontal cortex (mPFC), whereas increases in Bdnf expression were observed only in the amygdala after extinction training. Extinction enhancements were recapitulated when MDMA (1  μg) was infused directly into the basolateral complex of the amygdala (BLA), and enhancement was abolished when BDNF signaling was inhibited before extinction. These findings suggest that MDMA enhances fear memory extinction through a BDNF-dependent mechanism, and that MDMA may be a useful adjunct to exposure-based therapies for PTSD and other anxiety disorders characterized by altered fear learning.

Young, M. B., Andero, R., Ressler, K. J., & Howell, L. L. (2015). 3, 4-Methylenedioxymethamphetamine facilitates fear extinction learning. Translational Psychiatry, 5(9), e634. http://dx.doi.org/10.1038/tp.2015.138

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IJTS Special Topic Section: Ketamine ● Ketamine Psychedelic Psychotherapy: Focus on its Pharmacology, Phenomenology, and Clinical Applications

January 1, 2014 / Ketamine, Papers, Psychiatry & Medicine, Psychology, Publications / By / , , , , , ,

Abstract

Meant to be an authoritative guide for psychiatrists and others interested in understanding and applying ketamine psychedelic psychotherapy (KPP), this paper focuses on its pharmacology, phenomenology, and clinical applications. Ketamine is a dissociative anesthetic widely used by physicians and veterinarians in the United States. In addition to its anesthetic and dissociative properties, ketamine also has a multitude of other psychological and pharmacological properties, which include analgesic, sedative, neuroprotective, anxiolytic, antidepressant, stimulant, euphoriant, and hallucinogenic effects. The literature on the clinical application of KPP is comprehensively reviewed, practical advice for using KPP is given, and the pharmacology and phenomenology of ketamine-induced psychedelic experiences are explored, including in relationship to transpersonal healing and possible iatrogenic consequences of misuse of KPP.

Kolp, E., Krupitsky, E., Sylvester, M., Kolp, A., Friedman, H. L., Jansen, K., & Young, M. S. (2014). Ketamine Psychedelic Psychotherapy: Focus on its Pharmacology, Phenomenology, and Clinical Applications. International Journal of Transpersonal Studies, 33(2).
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