Vortioxetine restores reversal learning impaired by 5-HT depletion or chronic intermittent cold stress in rats.
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-HT3, 5-HT7 and 5-HT1D receptor antagonist, a 5-HT1B receptor partial agonist, a 5-HT1A 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.
Department of Pharmacology and Center for Biomedical Neuroscience,University of Texas Health Science Center at San Antonio,San Antonio, TX 78229,USA.
Ashley
A
Wallace
Lundbeck Research USA,Paramus, NJ 07652,USA.
Alan L
AL
Pehrson
Lundbeck Research USA,Paramus, NJ 07652,USA.
Connie
C
Sánchez
Department of Pharmacology and Center for Biomedical Neuroscience,University of Texas Health Science Center at San Antonio,San Antonio, TX 78229,USA.
David A
DA
Morilak
D000704:Analysis of Variance; D000818:Animals; D014151:Anti-Anxiety Agents / Q000627:therapeutic use*; D001288:Attention / Q000187:drug effects; D001345:Autoradiography; D001835:Body Weight / Q000187:drug effects; D003080:Cold Temperature / Q000009:adverse effects; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007859:Learning Disabilities / Q000188:drug therapy*; D008297:Male; D010649:Phenylalanine / Q000031:analogs & derivatives / Q000494:pharmacology; D010879:Piperazines / Q000627:therapeutic use*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012193:Reversal Learning; D012701:Serotonin / Q000172:deficiency*; D013315:Stress, Psychological / Q000150:complications* / Q000209:etiology; D013440:Sulfides / Q000627:therapeutic use*; D000078784:Vortioxetine
D014151:Anti-Anxiety Agents; D004791:Enzyme Inhibitors; D010879:Piperazines; D013440:Sulfides; C034515:phenylalanine methyl ester; D012701:Serotonin; D000078784:Vortioxetine; D010649:Phenylalanine