Psychedelics such as psilocybin show great promise for the treatment of depression and PTSD, but their long duration of action poses practical limitations for patient access. 4-OH-DiPT is a fast-acting and shorter-lasting derivative of psilocybin. Here we characterized the pharmacological profile of 4-OH-DiPT and examined its impact on fear extinction learning as well as a potential mechanism of action. First, we profiled 4-OH-DiPT at all 12 human 5-HT GPCRs. 4-OH-DiPT showed strongest agonist activity at all three 5-HT2A/2B/2C receptors with near full agonist activity at 5-HT2A. Notably, 4-OH-DiPT had comparable activity at mouse and human 5-HT2A/2B/2C receptors. In a fear extinction paradigm, 4-OH-DiPT significantly reduced freezing responses to conditioned cues in a dose-dependent manner with a greater potency in female mice than male mice. Female mice that received 4-OH-DiPT before extinction training had reduced avoidance behaviors several days later in the light dark box, elevated plus maze and novelty-suppressed feeding test compared to controls, while male mice did not show significant differences. 4-OH-DiPT produced robust increases in spontaneous inhibitory postsynaptic currents (sIPSCs) in basolateral amygdala (BLA) principal neurons and action potential firing in BLA interneurons in a 5-HT2A-dependent manner. RNAscope demonstrates that Htr2a mRNA is expressed predominantly in BLA GABA interneurons, Htr2c mRNA is expressed in both GABA interneurons and principal neurons, while Htr2b mRNA is absent in the BLA. Our findings suggest that 4-OH-DiPT activates BLA interneurons via the 5-HT2A receptor to enhance GABAergic inhibition of BLA principal neurons, which provides a potential mechanism for suppressing learned fear.
This is a preview of subscription content, access via your institution
Subscribe to this journal
Receive 13 print issues and online access
$259.00 per year
only $19.92 per issue
Rent or buy this article
Prices vary by article type
Prices may be subject to local taxes which are calculated during checkout
Hoppen TH, Morina N. The prevalence of PTSD and major depression in the global population of adult war survivors: a meta-analytically informed estimate in absolute numbers. Eur J Psychotraumatol. 2019;10:1578637.
Yehuda R, Hoge CW, McFarlane AC, Vermetten E, Lanius RA, Nievergelt CM, et al. Post-traumatic stress disorder. Nat Rev Dis Prim. 2015;1:15057.
Bisson JI, Roberts NP, Andrew M, Cooper R, Lewis C. Psychological therapies for chronic post-traumatic stress disorder (PTSD) in adults. Cochrane Database Syst Rev. 2013;2013:CD003388.
Bisson J, Andrew M. Psychological treatment of post-traumatic stress disorder (PTSD). Cochrane Database Syst Rev. 2007:Cd003388. https://doi.org/10.1002/14651858.CD003388.pub3.
Kessler RC, Sonnega A, Bromet E, Hughes M, Nelson CB. Posttraumatic Stress Disorder in the National Comorbidity Survey. Arch Gen Psychiatry. 1995;52:1048–60.
Bradley R, Greene J, Russ E, Dutra L, Westen D. A Multidimensional Meta-Analysis of Psychotherapy for PTSD. Am J Psychiatry. 2005;162:214–27.
van der Kolk BA, Dreyfuss D, Michaels M, Shera D, Berkowitz R, Fisler R, et al. Fluoxetine in posttraumatic stress disorder. J Clin Psychiatry. 1994;55:517–22.
Meltzer-Brody S, Connor KM, Churchill E, Davidson JR. Symptom-specific effects of fluoxetine in post-traumatic stress disorder. Int Clin Psychopharmacol. 2000;15:227–31.
Martenyi F, Brown EB, Zhang H, Prakash A, Koke SC. Fluoxetine versus placebo in posttraumatic stress disorder. J Clin Psychiatry. 2002;63:199–206.
Barrett FS, Doss MK, Sepeda ND, Pekar JJ, Griffiths RR. Emotions and brain function are altered up to one month after a single high dose of psilocybin. Sci Rep. 2020;10:2214.
Carhart-Harris R, Giribaldi B, Watts R, Baker-Jones M, Murphy-Beiner A, Murphy R, et al. Trial of Psilocybin versus Escitalopram for Depression. N. Engl J Med. 2021;384:1402–11.
Davis AK, Barrett FS, May DG, Cosimano MP, Sepeda ND, Johnson MW, et al. Effects of Psilocybin-Assisted Therapy on Major Depressive Disorder. JAMA Psychiatry. 2021;78:481.
Carhart-Harris RL, Bolstridge M, Rucker J, Day CM, Erritzoe D, Kaelen M, et al. Psilocybin with psychological support for treatment-resistant depression: an open-label feasibility study. Lancet Psychiatry. 2016;3:619–27.
Carhart-Harris RL, Bolstridge M, Day CM, Rucker J, Watts R, Erritzoe DE, et al. Psilocybin with psychological support for treatment-resistant depression: six-month follow-up. Psychopharmacology. 2018;235:399–408.
Mitchell JM, Bogenschutz M, Lilienstein A, Harrison C, Kleiman S, Parker-Guilbert K, et al. MDMA-assisted therapy for severe PTSD: a randomized, double-blind, placebo-controlled phase 3 study. Nat Med. 2021;27:1025–33.
Yaden DB, Griffiths RR. The Subjective Effects of Psychedelics Are Necessary for Their Enduring Therapeutic Effects. ACS Pharmacol Transl Sci. 2021;4:568–72.
Nutt D, Erritzoe D, Carhart-Harris R. Psychedelic Psychiatry’s Brave New World. Cell. 2020;181:24–8.
Holze F, Becker AM, Kolaczynska KE, Duthaler U, Liechti ME. Pharmacokinetics and Pharmacodynamics of Oral Psilocybin Administration in Healthy Participants. Clin Pharmacol Therapeutics. 2023;113:822–31.
Vargas MV, Meyer R, Avanes AA, Rus M, Olson DE. Psychedelics and Other Psychoplastogens for Treating Mental Illness. Front Psychiatry. 2021;12:727117.
Alexander Shulgin, Ann Shulgin. TiHKAL: The Continuation Transform Press: Berkeley, California; 1997.
Erowid. 4-HO-DiPT Reports. Jun 23, 2004. https://www.erowid.org/experiences/subs/exp_4HODiPT.shtml.
Klein AK, Chatha M, Laskowski LJ, Anderson EI, Brandt SD, Chapman SJ, et al. Investigation of the structure–activity relationships of psilocybin analogues. ACS Pharmacol Transl Sci. 2020;4:533–42.
Gatch MB, Hoch A, Carbonaro TM. Discriminative Stimulus Effects of Substituted Tryptamines in Rats. ACS Pharm Transl Sci. 2021;4:467–71.
Halberstadt AL, Geyer MA. Characterization of the head-twitch response induced by hallucinogens in mice: detection of the behavior based on the dynamics of head movement. Psychopharmacol (Berl). 2013;227:727–39.
Madsen MK, Fisher PM, Burmester D, Dyssegaard A, Stenbæk DS, Kristiansen S, et al. Psychedelic effects of psilocybin correlate with serotonin 2A receptor occupancy and plasma psilocin levels. Neuropsychopharmacology. 2019;44:1328–34.
Zamberlan F, Sanz C, Martínez Vivot R, Pallavicini C, Erowid F, Erowid E, et al. The Varieties of the Psychedelic Experience: A Preliminary Study of the Association Between the Reported Subjective Effects and the Binding Affinity Profiles of Substituted Phenethylamines and Tryptamines. Front Integr Neurosci. 2018;12:54.
Ballentine G, Friedman SF, Bzdok D. Trips and neurotransmitters: discovering principled patterns across 6850 hallucinogenic experiences. Sci Adv. 2022;8:eabl6989.
Wessa M, Flor H. Failure of extinction of fear responses in posttraumatic stress disorder: evidence from second-order conditioning. Am J Psychiatry. 2007;164:1684–92.
Norrholm SD, Jovanovic T, Olin IW, Sands LA, Karapanou I, Bradley B, et al. Fear extinction in traumatized civilians with posttraumatic stress disorder: relation to symptom severity. Biol Psychiatry. 2011;69:556–63.
Milad MR, Quirk GJ. Fear extinction as a model for translational neuroscience: ten years of progress. Annu Rev Psychol. 2012;63:129–51.
Wolff SBE, Gründemann J, Tovote P, Krabbe S, Jacobson GA, Müller C, et al. Amygdala interneuron subtypes control fear learning through disinhibition. Nature. 2014;509:453–58.
Grewe BF, Gründemann J, Kitch LJ, Lecoq JA, Parker JG, Marshall JD, et al. Neural ensemble dynamics underlying a long-term associative memory. Nature. 2017;543:670–75.
Herry C, Ciocchi S, Senn V, Demmou L, Müller C, Lüthi A. Switching on and off fear by distinct neuronal circuits. Nature. 2008;454:600–6.
Morilak DA, Garlow SJ, Ciaranello RD. Immunocytochemical localization and description of neurons expressing serotonin2 receptors in the rat brain. Neuroscience. 1993;54:701–17.
McDonald AJ, Mascagni F. Neuronal localization of 5-HT type 2A receptor immunoreactivity in the rat basolateral amygdala. Neuroscience. 2007;146:306–20.
Bombardi C. Distribution of 5-HT2A receptor immunoreactivity in the rat amygdaloid complex and colocalization with γ-aminobutyric acid. Brain Res. 2011;1370:112–28.
Wang F, Flanagan J, Su N, Wang LC, Bui S, Nielson A, et al. RNAscope: a novel in situ RNA analysis platform for formalin-fixed, paraffin-embedded tissues. J Mol Diagnostics: JMD. 2012;14:22–9.
Lewis V, Bonniwell EM, Lanham JK, Ghaffari A, Sheshbaradaran H, Cao AB, et al. A non-hallucinogenic LSD analog with therapeutic potential for mood disorders. Cell Rep. 2023;42:112203.
Kenakin T, Watson C, Muniz-Medina V, Christopoulos A, Novick S. A Simple Method for Quantifying Functional Selectivity and Agonist Bias. ACS Chem Neurosci. 2012;3:193–203.
Vickstrom CR, Liu X, Liu S, Hu MM, Mu L, Hu Y, et al. Role of endocannabinoid signaling in a septohabenular pathway in the regulation of anxiety- and depressive-like behavior. Mol Psychiatry. 2021;26:3178–91.
Liu X, Li Y, Yu L, Vickstrom CR, Liu QS. VTA mTOR signaling regulates dopamine dynamics, cocaine-induced synaptic alterations, and reward. Neuropsychopharmacology. 2018;43:1066–77.
Zhong P, Wang W, Yu F, Nazari M, Liu X, Liu QS. Phosphodiesterase 4 inhibition impairs cocaine-induced inhibitory synaptic plasticity and conditioned place preference. Neuropsychopharmacology. 2012;37:2377–87.
Mu L, Liu X, Yu H, Hu M, Friedman V, Kelly TJ, et al. Ibudilast attenuates cocaine self-administration and prime- and cue-induced reinstatement of cocaine seeking in rats. Neuropharmacology. 2021;201:108830.
Liu X, Chen Y, Tong J, Reynolds AM, Proudfoot SC, Qi J, et al. Epac Signaling Is Required for Cocaine-Induced Change in AMPA Receptor Subunit Composition in the Ventral Tegmental Area. J Neurosci. 2016;36:4802–15.
Shukla AK, Xiao K, Lefkowitz RJ. Emerging paradigms of β-arrestin-dependent seven transmembrane receptor signaling. Trends Biochem Sci. 2011;36:457–69.
Rodriguiz RM, Nadkarni V, Means CR, Pogorelov VM, Chiu Y-T, Roth BL, et al. LSD-stimulated behaviors in mice require β-arrestin 2 but not β-arrestin 1. Sci Rep. 2021;11:17690.
Catlow BJ, Song S, Paredes DA, Kirstein CL, Sanchez-Ramos J. Effects of psilocybin on hippocampal neurogenesis and extinction of trace fear conditioning. Exp Brain Res. 2013;228:481–91.
Pędzich BD, Rubens S, Sekssaoui M, Pierre A, Van Schuerbeek A, Marin P, et al. Effects of a psychedelic 5-HT2A receptor agonist on anxiety-related behavior and fear processing in mice. Neuropsychopharmacology. 2022;47:1304–14.
De La Fuente Revenga M, Zhu B, Guevara CA, Naler LB, Saunders JM, Zhou Z, et al. Prolonged epigenomic and synaptic plasticity alterations following single exposure to a psychedelic in mice. Cell Rep. 2021;37:109836.
Hagsäter SM, Pettersson R, Pettersson C, Atanasovski D, Näslund J, Eriksson E. A Complex Impact of Systemically Administered 5-HT2A Receptor Ligands on Conditioned Fear. Int J Neuropsychopharmacol. 2021;24:749–57.
Cameron LP, Benson CJ, Dunlap LE, Olson DE. Effects of N, N-Dimethyltryptamine on Rat Behaviors Relevant to Anxiety and Depression. ACS Chem Neurosci. 2018;9:1582–90.
Cameron LP, Benson CJ, DeFelice BC, Fiehn O, Olson DE. Chronic, Intermittent Microdoses of the Psychedelic N,N-Dimethyltryptamine (DMT) Produce Positive Effects on Mood and Anxiety in Rodents. ACS Chem Neurosci. 2019;10:3261–70.
Wiesenfeld-Hallin Z. Sex differences in pain perception. Gend Med. 2005;2:137–45.
Mineka S. The role of fear in theories of avoidance learning, flooding, and extinction. Psychol Bull. 1979;86:985–1010.
Solomon RL, Wynne LC. Traumatic avoidance learning: the principles of anxiety conservation and partial irreversibility. Psychol Rev. 1954;61:353–85.
Solomon RL, Kamin LJ, Wynne LC. Traumatic avoidance learning: the outcomes of several extinction procedures with dogs. J Abnorm Psychol. 1953;48:291–302.
Bourin M, Hascoët M. The mouse light/dark box test. Eur J Pharmacol. 2003;463:55–65.
Hogg S. A review of the validity and variability of the elevated plus-maze as an animal model of anxiety. Pharm Biochem Behav. 1996;54:21–30.
Prut L, Belzung C. The open field as a paradigm to measure the effects of drugs on anxiety-like behaviors: a review. Eur J Pharm. 2003;463:3–33.
Bodnoff SR, Suranyi-Cadotte B, Quirion R, Meaney MJ. A comparison of the effects of diazepam versus several typical and atypical anti-depressant drugs in an animal model of anxiety. Psychopharmacol (Berl). 1989;97:277–9.
Rex A, Voigt JP, Voits M, Fink H. Pharmacological evaluation of a modified open-field test sensitive to anxiolytic drugs. Pharm Biochem Behav. 1998;59:677–83.
Reijmers LG, Perkins BL, Matsuo N, Mayford M. Localization of a Stable Neural Correlate of Associative Memory. Science. 2007;317:1230–33.
Krabbe S, Gründemann J, Lüthi A. Amygdala Inhibitory Circuits Regulate Associative Fear Conditioning. Biol Psychiatry. 2018;83:800–09.
Dimidschstein J, Chen Q, Tremblay R, Rogers SL, Saldi GA, Guo L, et al. A viral strategy for targeting and manipulating interneurons across vertebrate species. Nat Neurosci. 2016;19:1743–49.
Rickli A, Moning OD, Hoener MC, Liechti ME. Receptor interaction profiles of novel psychoactive tryptamines compared with classic hallucinogens. Eur Neuropsychopharmacol. 2016;26:1327–37.
McKinney M, Raddatz R. Practical Aspects of Radioligand Binding. Curr Protocols Pharmacol. 2006;33:1.31-11.3.16.
Kobayashi H, Picard L-P, Schönegge A-M, Bouvier M. Bioluminescence resonance energy transfer–based imaging of protein–protein interactions in living cells. Nat Protoc. 2019;14:1084–107.
Stork O, Ji FY, Obata K. Reduction of extracellular GABA in the mouse amygdala during and following confrontation with a conditioned fear stimulus. Neurosci Lett. 2002;327:138–42.
Heldt SA, Ressler KJ. Training-induced changes in the expression of GABAA-associated genes in the amygdala after the acquisition and extinction of Pavlovian fear. Eur J Neurosci. 2007;26:3631–44.
Pape H-C, Stork O. Genes and Mechanisms in the Amygdala Involved in the Formation of Fear Memory. Ann N. Y Acad Sci. 2006;985:92–105.
Muller J, Corodimas KP, Fridel Z, LeDoux JE. Functional inactivation of the lateral and basal nuclei of the amygdala by muscimol infusion prevents fear conditioning to an explicit conditioned stimulus and to contextual stimuli. Behav Neurosci. 1997;111:683–91.
Jiang X, Xing G, Yang C, Verma A, Zhang L, Li H. Stress Impairs 5-HT2A Receptor-Mediated Serotonergic Facilitation of GABA Release in Juvenile Rat Basolateral Amygdala. Neuropsychopharmacology. 2009;34:410–23.
Rainnie DG. Serotonergic modulation of neurotransmission in the rat basolateral amygdala. J Neurophysiol. 1999;82:69–85.
Lucas EK, Jegarl AM, Morishita H, Clem RL. Multimodal and site-specific plasticity of amygdala parvalbumin interneurons after fear learning. Neuron. 2016;91:629–43.
Rothbaum BO, Schwartz AC. Exposure Therapy for Posttraumatic Stress Disorder. Am J Psychother. 2002;56:59–75.
This work was supported by National Institutes of Health Grants R01MH121454, DA047269 and R01DA035217 (to QSL), R35GM133421 (to JDM), and F31DA054759 (to VF). TJK is a member of the Medical Scientist Training Program at MCW, which is partially supported by a training grant from NIGMS T32-GM080202. It was also partially funded through the Research and Education Initiative Fund, a component of the Advancing a Healthier Wisconsin endowment at MCW.
The authors declare no competing interests.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Kelly, T.J., Bonniwell, E.M., Mu, L. et al. Psilocybin analog 4-OH-DiPT enhances fear extinction and GABAergic inhibition of principal neurons in the basolateral amygdala. Neuropsychopharmacol. (2023). https://doi.org/10.1038/s41386-023-01744-8