5-HT 1A Agonist Properties Contribute to a Robust Response to Vilazodone in the Novelty Suppressed Feeding Paradigm

• Published in: The international journal of neuropsychopharmacology 2016-06, Vol.19 (10), p.pyw057
• Main Authors: Garcia-Garcia, Alvaro L, Navarro-Sobrino, Míriam, Pilosof, Gila, Banerjee, Pradeep, Dranovsky, Alex, Leonardo, E David
• Format: Article
• Language: English
• ISSN: 1461-1457; 1469-5111
• DOI: 10.1093/ijnp/pyw057

Differences in 5-HT 1A receptor function have been implicated in vulnerability to depression and in response to treatment. Adding 5-HT 1A partial agonists to selective serotonin reuptake inhibitors has been touted as a strategy to increase their efficacy. Here we use the novelty suppressed feeding paradigm to compare the effects of vilazodone, a high-potency selective serotonin reuptake inhibitor, with high affinity for 5-HT 1A receptors to the reference selective serotonin reuptake inhibitor fluoxetine across several mouse strains that differ in their response to selective serotonin reuptake inhibitors. To confirm 5-HT 1A agonist activity, body temperature was measured after acute administration of vilazodone or fluoxetine, as administration of 5-HT 1A agonists induces hypothermia. We next used 3 strains of mice to examine the effects of the drugs on latency in the novelty suppressed feeding, a paradigm generally sensitive to chronic but not acute effects of antidepressants. Vilazodone induces robust hypothermia and blocks stress-induced hyperthermia in a 5-HT 1A -dependent manner, consistent with agonist effects at 5-HT 1A autoreceptors. In 129SvEv mice, vilazodone (10mg/kg/d) reduces the latency to eat in the novelty suppressed feeding test within 8 days, while no effect of fluoxetine (20mg/kg/d) was detected at that time. In contrast, both vilazodone and fluoxetine are effective at decreasing latency to eat in the novelty suppressed feeding paradigm in a strain with low autoreceptor levels. In mice with higher autoreceptor levels, no significant difference was detected between fluoxetine and vehicle ( P=. 8) or vilazodone and vehicle ( P =.06). In mice, vilazodone may offer advantages in time of onset and efficacy over a reference selective serotonin reuptake inhibitor in the novelty suppressed feeding test.