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Author Notes:

Correspondence: lhowell@emory.edu; (404)727-7786; 954 Gatewood Rd NE #2101, Atlanta, GA 30329.

With appreciation to the Abraham J. & Phyllis Katz Foundation for support of this research.

We thank the animal care and veterinary staff at the Yerkes National Primate Research Center (YNPRC) for maintaining the health and well-being of our research subjects, whom we thank greatly for their contribution.

M.B.Y. thanks Dr. Brian Dias for use of valuable behavioral equipment.

M.B.Y. also thanks Daniel Curry and Karly Hampshire for assistance with behavioral experiments.

M.B.Y. became employed by Shire Pharmaceuticals (Lexington, MA, USA) after completion of the studies described herein.

S.D.N, L.M.K., T.J., S.A.R. and C.R. report no funding or conflicts of interest relevant to this manuscript.


Research Funding:

M.B.Y. was supported by a NIH/NIGMS IRACDA grant K21 GM000680 awarded to Emory University.

L.L.H. was supported by NIH/NIDA K05 DA031246. B.O.R. has funding from Wounded Warrior Project, Department of Defense Clinical Trial Grant No.W81XWH-10-1-1045, “Enhancing Exposure Therapy for PTSD: Virtual Reality and Imaginal Exposure with a Cognitive Enhancer”, National Institute of Mental Health Grant No. 1R01MH094757-01, “Prospective Determination of Psychobiological Risk Factors for Posttraumatic Stress,” Brain and Behavior Research Foundation (NARSAD) Distinguished Investigator Grant, “Optimal Dose of early intervention to prevent PTSD”, and McCormick Foundation “Brave Heart: MLB's Welcome Back Veterans SouthEast Initiative.”

Dr. Rothbaum receives royalties from Oxford University Press, Guilford, APPI, and Emory University and received one advisory board payment from Genentech.

B.W.D. has received research support from Assurex, Axsome, Bristol-Myers Squibb, GlaxoSmithKline, Janssen, NIMH, Otsuka, Pfizer, and Takeda. He has served as a consultant to Pfizer and Medavante.


  • Science & Technology
  • Life Sciences & Biomedicine
  • Neurosciences
  • Pharmacology & Pharmacy
  • Psychiatry
  • Neurosciences & Neurology
  • Fear extinction
  • Serotonin
  • Monoamines
  • MDMA
  • Fear-potentiated startle
  • C57BL/6J MICE

Inhibition of serotonin transporters disrupts the enhancement of fear memory extinction by 3,4-methylenedioxymethamphetamine (MDMA)


Journal Title:

Психофармакология и биологическая нарко / Psychopharmacology and Biological Narcology


Volume 234, Number 19


, Pages 2883-2895

Type of Work:

Article | Post-print: After Peer Review


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-HT2Aantagonism 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-HT2Areceptors 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.

Copyright information:

© 2017, Springer-Verlag GmbH Germany.

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