000, p = 0.054, Bonferroni correction). IL-6 remained significantly increased in all treatment groups (LPS: U = 3.000, p = 0.018; Bonferroni correction, MDP + LPS: U = 2.000, p = 0.018, Bonferroni correction; FK565 + LPS, U = 2.000, p = 0.012, Bonferroni correction), comparable levels being seen in the MDP + LPS and FK565 + LPS treatment groups ( Fig. 5G). The expression of cytokine mRNAs in the brain was measured 3 and 26 h after injection of the PRR agonists in order to analyze cytokine expression at the time of predominant sickness and

depression-like behavior, respectively (Fig. 6). When cytokine mRNA was assessed 3 h post-treatment, two-way ANOVA revealed INCB024360 a NOD × LPS interaction for the expression of IFN-γ mRNA (F(2,42) = 5.911, p < 0.01) and a trend for IL-6 mRNA expression (F(2,42) = 2.774, p = 0.07). Post-hoc analysis disclosed that while neither MDP (3 mg/kg), FK565

(0.003 mg/kg) nor LPS (0.1 mg/kg) alone increased mRNA expression of IFN-γ or IL-6, combined treatment with MDP + LPS or FK565 + LPS increased IFN-γ and IL-6 mRNA expression compared to LPS or MDP and FK565, respectively ( Fig. 6A and C). In contrast, expression of IL-1β mRNA depended on LPS (F(1,42) = 24.984, p < 0.001) and the NOD PD-L1 inhibitor agonists (F(2,42) = 3.174, p ⩽ 0.05) without a significant interaction ( Fig. 6B). Likewise, TNF-α mRNA expression depended on LPS (F(1,42) = 25.735, p < 0.001) and the NOD agonists (F(2,42) = 8.535, p < 0.001) without a significant interaction ( Fig. 6D). Twenty-six hours after treatment, cerebral IFN-γ mRNA expression had returned to basal levels in all treatment groups (Fig. 6E). Conversely, the expression of IL-1β mRNA

remained significantly increased in response to MDP + LPS and FK565 + LPS (F(3,26) = 11.341, p < 0.001) and enhanced by trend in the LPS group (p = 0.085). In addition, IL-1β mRNA expression was significantly higher in the MDP + LPS group compared to the LPS group ( Fig. 6F). Likewise, TNF-α mRNA expression was increased in every treatment group (F(3,26) = 9.588, p < 0.001), with the highest expression seen in the MDP + LPS group ( Fig. 6H). In contrast, IL-6 mRNA expression was decreased in all treatment groups (F(3,26) = 13.621, p < 0.001) IKBKE ( Fig. 6G). The PRR agonists under study had a distinct effect to enhance the plasma levels of corticosterone as measured 3 h after injection. Two-way ANOVA revealed a significant main factor effect for LPS (F(1,40) = 76.581, p < 0.001) and the NOD agonists (F(2,40) = 16.608, p < 0.001) without a significant interaction. Post-hoc analysis of the main factor effects disclosed that FK565 increased circulating corticosterone compared to VEH and MDP ( Fig. 7A). One day after treatment, the plasma levels of corticosterone were examined 30 min after exposure to the TST.