title: The rapid recovery of 5-HT cell firing induced by the antidepressant vortioxetine involves 5-HT(3) receptor antagonism.
abstract: The therapeutic effect of current antidepressant drugs appears after several weeks of treatment and a significant number of patients do not respond to treatment. Here, we report the effects of the multi-modal antidepressant vortioxetine (Lu AA21004), a 5-HT(3) and 5-HT(7) receptor antagonist, 5-HT(1B) receptor partial agonist, 5-HT(1A) receptor agonist and 5-HT transporter (SERT) inhibitor, on rat 5-HT neurotransmission. Using in vivo electrophysiological recordings in the dorsal raphe nucleus of anaesthetized rats, we assessed the acute and subchronic effects of vortioxetine and/or the selective 5-HT(3) receptor agonist, SR57227 or the selective 5-HT(1A) receptor agonist flesinoxan, on 5-HT neuronal firing activity. Using ex-vivo autoradiography, we correlated SERT occupancy and presumed 5-HT firing activity. The selective serotonin reuptake inhibitor, fluoxetine, was used as comparator. Importantly, the recovery of 5-HT neuronal firing was achieved after 1 d with vortioxetine and 14 d with fluoxetine. SR57227 delayed this recovery. In contrast, vortioxetine failed to alter the reducing action of 3 d treatment of flesinoxan. Acute dosing of vortioxetine inhibited neuronal firing activity more potently than fluoxetine. SR57227 prevented the suppressant effect of vortioxetine, but not of fluoxetine. In contrast, flesinoxan failed to modify the suppressant effect of vortioxetine acutely administered. Differently to fluoxetine, vortioxetine suppressed neuronal firing without saturating occupancy at the SERT. Vortioxetine produced a markedly faster recovery of 5-HT neuronal firing than fluoxetine. This is at least partly due to 5-HT(3) receptor antagonism of vortioxetine in association with its reduced SERT occupancy.
authors.affiliation: Laboratory of Neuropsychopharmacology, University of Claude Bernard Lyon I, LYON Cedex 08, France.
authors.forename: Cécile
authors.initials: C
authors.lastname: Bétry
authors.forename: Alan L
authors.initials: AL
authors.lastname: Pehrson
authors.forename: Adeline
authors.initials: A
authors.lastname: Etiévant
authors.forename: Bjarke
authors.initials: B
authors.lastname: Ebert
authors.forename: Connie
authors.initials: C
authors.lastname: Sánchez
authors.forename: Nasser
authors.initials: N
authors.lastname: Haddjeri
mesh_terms: D000200:Action Potentials / Q000187:drug effects*; D000818:Animals; D000928:Antidepressive Agents / Q000494:pharmacology*; D001345:Autoradiography; D004334:Drug Administration Schedule; D016503:Drug Delivery Systems; D004573:Electrolytes / Q000009:adverse effects; D008297:Male; D009474:Neurons / Q000187:drug effects*; D010879:Piperazines / Q000494:pharmacology*; D010880:Piperidines / Q000494:pharmacology; D011903:Raphe Nuclei / Q000166:cytology / Q000293:injuries; D051381:Rats; D017207:Rats, Sprague-Dawley; D044406:Receptors, Serotonin, 5-HT3 / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism*; D058831:Serotonin 5-HT3 Receptor Antagonists / Q000494:pharmacology*; D050486:Serotonin Plasma Membrane Transport Proteins / Q000378:metabolism; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D013440:Sulfides / Q000494:pharmacology*; D013997:Time Factors; D000078784:Vortioxetine
chemical_list: D000928:Antidepressive Agents; D004573:Electrolytes; D010879:Piperazines; D010880:Piperidines; D044406:Receptors, Serotonin, 5-HT3; D058831:Serotonin 5-HT3 Receptor Antagonists; D050486:Serotonin Plasma Membrane Transport Proteins; D017366:Serotonin Receptor Agonists; D013440:Sulfides; D012701:Serotonin; D000078784:Vortioxetine; C056895:flesinoxan; C083009:4-amino-1-(6-chloro-2-pyridyl)piperidine hydrochloride