Serotonin is a neurotransmitter involved in many psychiatric diseases. In humans, a lack of 5-HT2B receptors is associated with serotonin-dependent phenotypes, including impulsivity and suicidality. A lack of 5-HT2B receptors in mice eliminates the effects of molecules that directly target serotonergic neurons including amphetamine derivative serotonin releasers, and selective serotonin reuptake inhibitor antidepressants. In this work, we tested the hypothesis that 5-HT2B receptors directly and positively regulate raphe serotonin neuron activity. By ex vivo electrophysiological recordings, we report that stimulation by the 5-HT2B receptor agonist, BW723C86, increased the firing frequency of serotonin Pet1-positive neurons. Viral overexpression of 5-HT2B receptors in these neurons increased their excitability. Furthermore, in vivo 5-HT2B-receptor stimulation by BW723C86 counteracted 5-HT1A autoreceptor-dependent reduction in firing rate and hypothermic response in wild-type mice. By a conditional genetic ablation that eliminates 5-HT2B receptor expression specifically and exclusively from Pet1-positive serotonin neurons (Htr2b5-HTKO mice), we demonstrated that behavioral and sensitizing effects of MDMA (3,4-methylenedioxy-methamphetamine), as well as acute behavioral and chronic neurogenic effects of the antidepressant fluoxetine, require 5-HT2B receptor expression in serotonergic neurons. In Htr2b5-HTKO mice, dorsal raphe serotonin neurons displayed a lower firing frequency compared to control Htr2blox/lox mice as assessed by in vivo extracellular recordings and a stronger hypothermic effect of 5-HT1A-autoreceptor stimulation was observed. The increase in head-twitch response to DOI (2,5-dimethoxy-4-iodoamphetamine) further confirmed the lower serotonergic tone resulting from the absence of 5-HT2B receptors in serotonin neurons. Together, these observations indicate that the 5-HT2B receptor acts as a direct positive modulator of serotonin Pet1-positive neurons in an opposite way as the known 5-HT1A-negative autoreceptor.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.


  1. 1.

    Commons KG. Ascending serotonin neuron diversity under two umbrellas. Brain Struct Funct. 2016;221:3347–60.

  2. 2.

    Okaty BW, Freret ME, Rood BD, Brust RD, Hennessy ML, Debairos D, et al. Multi-scale molecular deconstruction of the serotonin neuron system. Neuron. 2015;88:774–91.

  3. 3.

    Riad M, Garcia S, Watkins KC, Jodoin N, Doucet E, Langlois X, et al. Somatodendritic localization of 5-HT1A and preterminal axonal localization of 5-HT1B serotonin receptors in adult rat brain. J Comp Neurol. 2000;417:181–94.

  4. 4.

    Aghajanian GK, Lakoski JM. Hyperpolarization of serotonergic neurons by serotonin and LSD: studies in brain slices showing increased K+ conductance. Brain Res. 1984;305:181–5.

  5. 5.

    Andrade R, Huereca D, Lyons JG, Andrade EM, Mcgregor KM. 5-HT1A receptor-mediated autoinhibition and the control of serotonergic cell firing. ACS Chem Neurosci. 2015;6:1110–5.

  6. 6.

    Boothman LJ, Allers KA, Rasmussen K, Sharp T. Evidence that central 5-HT2A and 5-HT(2B/C) receptors regulate 5-HT cell firing in the dorsal raphe nucleus of the anaesthetised rat. Br J Pharmacol. 2003;139:998–1004.

  7. 7.

    Craven RM, Grahame-Smith DG, Newberry NR. 5-HT1A and 5-HT2 receptors differentially regulate the excitability of 5-HT-containing neurones of the guinea pig dorsal raphe nucleus in vitro. Brain Res. 2001;899:159–68.

  8. 8.

    Kirby LG, Pernar L, Valentino RJ, Beck SG. Distinguishing characteristics of serotonin and non-serotonin-containing cells in the dorsal raphe nucleus: electrophysiological and immunohistochemical studies. Neuroscience. 2003;116:669–83.

  9. 9.

    Liu R, Jolas T, Aghajanian G. Serotonin 5-HT(2) receptors activate local GABA inhibitory inputs to serotonergic neurons of the dorsal raphe nucleus. Brain Res. 2000;873:34–45.

  10. 10.

    Quérée P, Peters S, Sharp T. Further pharmacological characterization of 5-HT(2C) receptor agonist-induced inhibition of 5-HT neuronal activity in the dorsal raphe nucleus in vivo. Br J Pharmacol. 2009;158:1477–85.

  11. 11.

    Leon-Pinzon C, Cercós MG, Noguez P, Trueta C, De-Miguel FF. Exocytosis of serotonin from the neuronal soma is sustained by a serotonin and calcium-dependent feedback loop. Front Cell Neurosci. 2014;8:169.

  12. 12.

    Marinelli S, Schnell SA, Hack SP, Christie MJ, Wessendorf MW, Vaughan CW. Serotonergic and nonserotonergic dorsal raphe neurons are pharmacologically and electrophysiologically heterogeneous. J Neurophysiol. 2004;92:3532–7.

  13. 13.

    Bevilacqua L, Doly S, Kaprio J, Yuan Q, Tikkanen R, Paunio T, et al. A population-specific HTR2B stop codon predisposes to severe impulsivity. Nature. 2010;468:1061–6.

  14. 14.

    Banas SM, Doly S, Boutourlinsky K, Diaz SL, Belmer A, Callebert J, et al. Deconstructing antiobesity compound action: requirement of serotonin 5-HT2B receptors for dexfenfluramine anorectic effects. Neuropsychopharmacology. 2011;36:423–33.

  15. 15.

    Diaz SL, Maroteaux L. Implication of 5-HT2B receptors in the serotonin syndrome. Neuropharmacology. 2011;61:495–502.

  16. 16.

    Diaz SL, Doly S, Narboux-Nême N, Fernandez S, Mazot P, Banas S, et al. 5-HT2B receptors are required for serotonin-selective antidepressant actions. Mol Psychiatry. 2012;17:154–63.

  17. 17.

    Doly S, Bertran-Gonzalez J, Callebert J, Bruneau A, Banas SM, Belmer A, et al. Role of serotonin via 5-HT2B receptors in the reinforcing effects of MDMA in mice. PLoS ONE. 2009;4:e7952.

  18. 18.

    Doly S, Valjent E, Setola V, Callebert J, Herve D, Launay JM, et al. Serotonin 5-HT2B receptors are required for 3,4-methylenedioxymethamphetamine-induced hyperlocomotion and 5-HT release in vivo and in vitro. J Neurosci. 2008;28:2933–40.

  19. 19.

    Loric S, Launay J-M, Colas J-F, Maroteaux L. New mouse 5-HT2-like receptor: expression in brain, heart, and intestine. FEBS Lett. 1992;312:203–7.

  20. 20.

    Choi D-S, Birraux G, Launay J-M, Maroteaux L. The human serotonin 5-HT2B receptor: pharmacological link between 5-HT2 and 5-HT1D receptors. FEBS Lett. 1994;352:393–9.

  21. 21.

    Kursar JD, Nelson DL, Wainscott D, Baez M. Molecular cloning, functional expression, and mRNA tissue distribution of the human 5-hydroxytryptamine2B receptor. Mol Pharmacol. 1994;46:227–34.

  22. 22.

    Bonaventure P, Guo H, Tian B, Liu X, Bittner A, Roland B, et al. Nuclei and subnuclei gene expression profiling in mammalian brain. Brain Res. 2002;943:38–47.

  23. 23.

    Scott MM, Wylie CJ, Lerch JK, Murphy R, Lobur K, Herlitze S, et al. A genetic approach to access serotonin neurons for in vivo and in vitro studies. Proc Natl Acad Sci USA. 2005;102:16472–7.

  24. 24.

    Fernandez SP, Cauli B, Cabezas C, Muzerelle A, Poncer J-C, Gaspar P. Multiscale single-cell analysis reveals unique phenotypes of raphe 5-HT neurons projecting to the forebrain. Brain Struct Funct. 2016;221:4007–25.

  25. 25.

    Vandermaelen CP, Aghajanian GK. Electrophysiological and pharmacological characterization of serotonergic dorsal raphe neurons recorded extracellularly and intracellularly in rat brain slices. Brain Res. 1983;289:109–19.

  26. 26.

    Muzerelle A, Scotto-Lomassese S, Bernard JF, Soiza-Reilly M, Gaspar P. Conditional anterograde tracing reveals distinct targeting of individual serotonin cell groups (B5-B9) to the forebrain and brainstem. Brain Struct Funct. 2016;221:535–61.

  27. 27.

    Maroteaux M, Mameli M. Cocaine evokes projection-specific synaptic plasticity of lateral habenula neurons. J Neurosci. 2012;32:12641–6.

  28. 28.

    Bill DJ, Knight M, Forster EA, Fletcher A. Direct evidence for an important species difference in the mechanism of 8-OH-DPAT-induced hypothermia. Br J Pharmacol. 1991;103:1857–64.

  29. 29.

    Rainer Q, Nguyen HT, Quesseveur G, Gardier AM, David DJ, Guiard BP. Functional status of somatodendritic serotonin 1A autoreceptor after long-term treatment with fluoxetine in a mouse model of anxiety/depression based on repeated corticosterone administration. Mol Pharmacol. 2012;81:106–12.

  30. 30.

    Aghajanian GK, Vandermaelen CP. Intracellular recording in vivo from serotonergic neurons in the rat dorsal raphe nucleus: methodological considerations. J Histochem Cytochem. 1982;30:813–4.

  31. 31.

    Pitychoutis P, Belmer A, Moutkine I, Adrien J, Maroteaux L. Mice lacking the serotonin Htr2B receptor gene present an antipsychotic-sensitive schizophrenic-like phenotype. Neuropsychopharmacology. 2015;40:2764–73.

  32. 32.

    Gray EG, Whittaker VP. The isolation of nerve endings from brain: an electron-microscopic study of cell fragments derived by homogenization and centrifugation. J Anat. 1962;96:79–88.

  33. 33.

    Haddjeri N, Lavoie N, Blier P. Electrophysiological evidence for the tonic activation of 5-HT(1A) autoreceptors in the rat dorsal raphe nucleus. Neuropsychopharmacology. 2004;29:1800–6.

  34. 34.

    Jacobsen JPR, Siesser WB, Sachs BD, Peterson S, Cools MJ, Setola V, et al. Deficient serotonin neurotransmission and depression-like serotonin biomarker alterations in tryptophan hydroxylase 2 (Tph2) loss-of-function mice. Mol Psychiatry. 2012;17:694–704.

  35. 35.

    Richardson-Jones JW, Craige CP, Guiard BP, Stephen A, Metzger KL, Kung HF, et al. 5-HT1A autoreceptor levels determine vulnerability to stress and response to antidepressants. Neuron. 2010;65:40–52.

  36. 36.

    Crespi D, Mennini T, Gobbi M. Carrier-dependent and Ca(2+)-dependent 5-HT and dopamine release induced by (+)-amphetamine, 3,4-methylendioxymethamphetamine, p-chloroamphetamine and (+)-fenfluramine. Br J Pharmacol. 1997;121:1735–43.

  37. 37.

    Valjent E, Bertran-Gonzalez J, Aubier B, Greengard P, Hervé D, Girault J-A. Mechanisms of locomotor sensitization to drugs of abuse in a two-injection protocol. Neuropsychopharmacology. 2010;35:401–15.

  38. 38.

    Halberstadt AL. Recent advances in the neuropsychopharmacology of serotonergic hallucinogens. Behav Brain Res. 2015;277:99–120.

  39. 39.

    Calizo LH, Akanwa A, Ma X, Pan Y-Z, Lemos JC, Craige C, et al. Raphe serotonin neurons are not homogenous: electrophysiological, morphological and neurochemical evidence. Neuropharmacology. 2011;61:524–43.

  40. 40.

    Andrade R, Haj-Dahmane S. Serotonin neuron diversity in the dorsal raphe. ACS Chem Neurosci. 2013;4:22–25.

  41. 41.

    Gaspar P, Lillesaar C. Probing the diversity of serotonin neurons. Philos Trans R Soc Lond Ser B. 2012;367:2382–94.

  42. 42.

    Altieri SC, Garcia-Garcia AL, Leonardo ED, Andrews AM. Rethinking 5-HT1A receptors: emerging modes of inhibitory feedback of relevance to emotion-related behavior. ACS Chem Neurosci. 2013;4:72–83.

  43. 43.

    Bang SJ, Jensen P, Dymecki SM, Commons KG. Projections and interconnections of genetically defined serotonin neurons in mice. Eur J Neurosci. 2012;35:85–96.

  44. 44.

    Beck SG, Pan Y-Z, Akanwa AC, Kirby LG. Median and dorsal raphe neurons are not electrophysiologically identical. J Neurophysiol. 2004;91:994–1005.

  45. 45.

    Colgan LA, Putzier I, Levitan ES. Activity-dependent vesicular monoamine transporter-mediated depletion of the nucleus supports somatic release by serotonin neurons. J Neurosci. 2009;29:15878–87.

  46. 46.

    Courtney NA, Ford CP. Mechanisms of 5-HT1A receptor-mediated transmission in dorsal raphe serotonin neurons. J Physiol. 2016;594:953–65.

  47. 47.

    Janoshazi A, Deraet M, Callebert J, Setola V, Guenther S, Saubamea B, et al. Modified receptor internalization upon co-expression of 5-HT1B receptor and 5-HT2B receptors. Mol Pharmacol. 2007;71:1463–74.

  48. 48.

    Teissier A, Chemiakine A, Inbar B, Bagchi S, Ray RS, Palmiter RD, et al. Activity of raphé serotonergic neurons controls emotional behaviors. Cell Rep. 2015;13:1965–76.

  49. 49.

    Urban DJ, Zhu H, Marcinkiewcz CA, Michaelides M, Oshibuchi H, Rhea D, et al. Elucidation of the behavioral program and neuronal network encoded by dorsal raphe serotonergic neurons. Neuropsychopharmacology. 2016;41:1404–15.

  50. 50.

    Colgan LA, Cavolo SL, Commons KG, Levitan ES. Action potential-independent and pharmacologically unique vesicular serotonin release from dendrites. J Neurosci. 2012;32:15737–46.

  51. 51.

    de Kock CPJ, Cornelisse LN, Burnashev N, Lodder JC, Timmerman AJ, Couey JJ, et al. NMDA receptors trigger neurosecretion of 5-HT within dorsal raphe nucleus of the rat in the absence of action potential firing. J Physiol. 2006;577(Part 3):891–905.

  52. 52.

    Holohean AM, Hackman JC. Mechanisms intrinsic to 5-HT2B receptor-induced potentiation of NMDA receptor responses in frog motoneurones. Br J Pharmacol. 2004;143:351–60.

  53. 53.

    Igata S, Hayashi T, Itoh M, Akasu T, Takano M, Ishimatsu M. Persistent α1-adrenergic receptor function in the nucleus locus coeruleus causes hyperexcitability in AD/HD model rats. J Neurophysiol. 2014;111:777–86.

  54. 54.

    Aghajanian GK, VanderMaelen CP. Alpha 2-adrenoceptor-mediated hyperpolarization of locus coeruleus neurons: intracellular studies in vivo. Science (New York, NY). 1982;215:1394–6.

  55. 55.

    Williams JT, Marshall KC. Membrane properties and adrenergic responses in locus coeruleus neurons of young rats. J Neurosci. 1987;7:3687–94.

  56. 56.

    Brandman O, Meyer T. Feedback loops shape cellular signals in space and time. Science (New York, NY). 2008;322:390–5.

Download references


We thank the Mouse Clinical Institute (Strasbourg) for Htr2b-floxed mice production, Evan Deneris for providing Pet1-Cre BAC transgenic mice, Mythili Savariradjane and the Imaging facility of the IFM, and Natacha Roblot and the IFM animal facility.


This work has been supported by funds from the Centre National de la Recherche Scientifique, the Institut National de la Santé et de la Recherche Médicale, the Université Pierre et Marie Curie, and by grants from the Fondation pour la Recherche Médicale “Equipe FRM DEQ2014039529”, the French Ministry of Research (Agence Nationale pour la Recherche ANR-12-BSV1-0015 and ANR-17-CE16-0008 and the Investissements d’Avenir programme ANR-11-IDEX-0004-02). LM’s team is part of the École des Neurosciences de Paris Ile-de-France network and of the Bio-Psy Labex and as such this work was supported by French state funds managed by the ANR within the Investissements d’Avenir programme under reference ANR-11-IDEX-0004-02.

Author contributions

AB, EQ, SLD, SPF, SD, SMB, PMP, IM, AM, and AT conducted the experiments; AR conducted and designed the experiments; BPG conducted, designed the experiments, and wrote the paper; MM supervised, wrote the paper, and provided funding; LM supervised, wrote the paper, and provided funding.

Author information

Author notes

  1. Arnauld Belmer and Emily Quentin contributed equally to this work.


  1. INSERM UMR-S 839, 75005, Paris, France

    • Arnauld Belmer
    • , Emily Quentin
    • , Silvina L. Diaz
    • , Sebastian P. Fernandez
    • , Stéphane Doly
    • , Sophie M. Banas
    • , Pothitos M. Pitychoutis
    • , Imane Moutkine
    • , Aude Muzerelle
    • , Anna Tchenio
    • , Anne Roumier
    • , Manuel Mameli
    •  & Luc Maroteaux
  2. Sorbonne Universités, UPMC Univ Paris 6, 75005, Paris, France

    • Arnauld Belmer
    • , Emily Quentin
    • , Silvina L. Diaz
    • , Sebastian P. Fernandez
    • , Stéphane Doly
    • , Sophie M. Banas
    • , Pothitos M. Pitychoutis
    • , Imane Moutkine
    • , Aude Muzerelle
    • , Anna Tchenio
    • , Anne Roumier
    • , Manuel Mameli
    •  & Luc Maroteaux
  3. Institut du Fer à Moulin, 75005, Paris, France

    • Arnauld Belmer
    • , Emily Quentin
    • , Silvina L. Diaz
    • , Sebastian P. Fernandez
    • , Stéphane Doly
    • , Sophie M. Banas
    • , Pothitos M. Pitychoutis
    • , Imane Moutkine
    • , Aude Muzerelle
    • , Anna Tchenio
    • , Anne Roumier
    • , Manuel Mameli
    •  & Luc Maroteaux
  4. Translational Research Institute, Queensland University of Technology, Brisbane, QLD, 4059, Australia

    • Arnauld Belmer
  5. Instituto de Biología Celular y Neurociencia, Fac. de Cs. Exactas, Químicas y Naturales, Universidad de Morón, UBA-CONICET – Paraguay 2155, 3° piso, C1121ABG, Buenos Aires, Argentina

    • Silvina L. Diaz
  6. Research Center on Animal Cognition, Center for Integrative Biology, 31062, Toulouse, France

    • Bruno P. Guiard
  7. Université Paul Sabatier, 31062, Toulouse, France

    • Bruno P. Guiard
  8. UMR5169 CNRS, 31062, Toulouse, France

    • Bruno P. Guiard
  9. IPMC – CNRS UMR7275 660 Route des Lucioles Sophia-Antipolis, 06560, Valbonne, France

    • Sebastian P. Fernandez
  10. Université Clermont Auvergne, INSERM, NEURO-DOL, 63000, Clermont-Ferrand, France

    • Stéphane Doly
  11. Department of Biology and Center for Tissue Regeneration and Engineering at Dayton (TREND), University of Dayton, Dayton, OH, USA

    • Pothitos M. Pitychoutis
  12. Dept. Fundamental Neurosciences (DNF) The University of Lausanne, Lausanne, Switzerland

    • Anna Tchenio
    •  & Manuel Mameli


  1. Search for Arnauld Belmer in:

  2. Search for Emily Quentin in:

  3. Search for Silvina L. Diaz in:

  4. Search for Bruno P. Guiard in:

  5. Search for Sebastian P. Fernandez in:

  6. Search for Stéphane Doly in:

  7. Search for Sophie M. Banas in:

  8. Search for Pothitos M. Pitychoutis in:

  9. Search for Imane Moutkine in:

  10. Search for Aude Muzerelle in:

  11. Search for Anna Tchenio in:

  12. Search for Anne Roumier in:

  13. Search for Manuel Mameli in:

  14. Search for Luc Maroteaux in:

Conflict of interest

AR has been supported by grants from the Université Pierre et Marie Curie (Emergence-UPMC program) and the Bio-Psy Labex. SD has been supported by a fellowship of the Lefoulon-DeLalande foundation, SLD from the Region Ile-de France DIM STEM and from the ANPCyT (PICT 2013-3225), CONICET (PIP-11220130100157CO), and University of Moron (PID 2015), and EQ by a PhD fellowship from the Region Ile-de France DIM Cerveau et Pensée. The other authors declare that they have no conflict of interest.

Corresponding author

Correspondence to Luc Maroteaux.

Electronic supplementary material

About this article

Publication history





Issue Date



Further reading