cruzi-induced depression. The SSRI antidepressant FX has anti-inflammatory activity; it decreases IFNγ, upregulates IL-10 and inhibits the activation of NF-κB (Abdel-Salam et al., 2004 and Koh et al., 2011). NF-κB is a nuclear factor crucial for TNF gene transcription Talazoparib manufacturer (Tracey et al., 2008). Hence, we tested whether the beneficial effect of FX in T. cruzi-induced depressive disorder was related to the systemic down-regulation of TNF mRNA. This was not the case, however, as similar TNF mRNA levels were detected in saline- and FX-treated T. cruzi-infected mice. Subsequently, the participation of
TNF in T. cruzi-induced depressive-like behavior was tested by treating chronically (120 dpi) T. cruzi-infected C57BL/6 mice with PTX, a phosphodiesterase inhibitor
that decreases TNF synthesis ( Shaw et al., 2009), or the chimeric anti-TNF neutralizing monoclonal antibody infliximab ( Tracey et al., 2008). Although TNF plays an important role in parasite control in the acute phase of infection ( Lannes-Vieira et al., 2011), no parasite burden was observed, suggesting that infection was not reactivated or reacutized by interfering with TNF in chronically T. cruzi-infected mice. Importantly, the immobility time assessed by the TST was significantly decreased after PTX and anti-TNF administration, supporting the idea that TNF may have a pivotal role in the induction of depressive-like behavior during chronic infection. Accordingly, exogenous TNF administration induces acute depressive-like behavior, supporting a role for this cytokine in behavioral alterations ( Kaster selleck chemicals et al., 2012). Despite the very low parasite load, patients develop more severe forms of Chagas disease during the chronic stage
( Dutra et al., 2009 and Rassi et al., 2010), when high TNF levels in the serum are detected ( Ferreira et al., 2003, Talvani et al., 2004 and Gomes et al., 2005). Our study highlights that T. cruzi-induced long-lasting TNF expression may contribute to depressive-like behavior in Chagas disease. Because non-infectious chronic cardiac disorders are associated RG7420 chemical structure with high TNF levels ( Shaw et al., 2009), our findings become more broadly important. Interestingly, Bz and PTX also regulate NF-κB activation ( Shaw et al., 2009 and Manarin et al., 2010). Therefore, the genesis of depressive-like behavior in Chagas disease may reside in a complex network of interactions triggered by the parasite that involve the immune stressor TNF and mechanisms that may induce increase in TRYCATs and serotonin paucity ( Fig. S4). Altogether, our findings support the existence of a chronic nervous form of Chagas disease, contribute to the understanding of pathogen-borne cytokine-driven chronic depression and open new avenues for therapeutic interventions in depressive disorders. Our results indicate that T.