Vortioxetine restores reversal learning impaired by 5-HT depletion or chronic intermittent cold stress in rats

Ashley Wallace, Alan L. Pehrson, Connie Sánchez, David A Morilak

Research output: Contribution to journalArticle

63 Scopus citations

Abstract

Current treatments for depression, including serotonin-specific reuptake inhibitors (SSRIs), are only partially effective, with a high incidence of residual symptoms, relapse, and treatment resistance. Loss of cognitive flexibility, a component of depression, is associated with dysregulation of the prefrontal cortex. Reversal learning, a form of cognitive flexibility, is impaired by chronic stress, a risk factor for depression, and the stress-induced impairment in reversal learning is sensitive to chronic SSRI treatment, and is mimicked by serotonin (5-HT) depletion. Vortioxetine, a novel, multimodal-acting antidepressant, is a 5-HT<inf>3</inf>, 5-HT<inf>7</inf> and 5-HT<inf>1D</inf> receptor antagonist, a 5-HT<inf>1B</inf> receptor partial agonist, a 5-HT<inf>1A</inf> receptor agonist, and inhibits the 5-HT transporter. Using adult male rats, we first investigated the direct effects of vortioxetine, acting at post-synaptic 5-HT receptors, on reversal learning that was compromised by 5-HT depletion using 4-chloro-DL-phenylalanine methyl ester hydrochloride (PCPA), effectively eliminating any contribution of 5-HT reuptake blockade. PCPA induced a reversal learning impairment that was alleviated by acute or sub-chronic vortioxetine administration, suggesting that post-synaptic 5-HT receptor activation contributes to the effects of vortioxetine. We then investigated the effects of chronic dietary administration of vortioxetine on reversal learning that had been compromised in intact animals exposed to chronic intermittent cold (CIC) stress, to assess vortioxetine's total pharmacological effect. CIC stress impaired reversal learning, and chronic vortioxetine administration prevented the reversal-learning deficit. Together, these results suggest that the direct effect of vortioxetine at 5-HT receptors may contribute to positive effects on cognitive flexibility deficits, and may enhance the effect of 5-HT reuptake blockade.

Original languageEnglish (US)
JournalInternational Journal of Neuropsychopharmacology
Volume29
Issue number4
DOIs
StatePublished - May 23 2014

Keywords

  • Antidepressant
  • chronic stress
  • cognitive flexibility
  • orbitofrontal cortex
  • reversal learning
  • serotonin

ASJC Scopus subject areas

  • Pharmacology (medical)
  • Pharmacology
  • Psychiatry and Mental health

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