The glucocorticoid receptor (GR) seems to become essential for GC-induced sensitization. Many research have shown that stress-induced microglial activation and potentiation of neuroinflammatory processes is blocked by a GC receptor antagonist (de Pablos et al., 2006; Espinosa-Oliva et al., 2011; Munhoz et al., 2006; Nair and Bonneau, 2006). We have demonstrated that blocking GR activity in the course of a stressor with RU486 prevents stress-induced sensitization to a subsequent immune HSP70 Activator site challenge in vivo, as well as the priming of microglia observed ex vivo (Frank et al., 2012). Despite the fact that the effects of stress-induced sensitization seem to be mediated, at least in portion, by improved GC levels, the mechanism(s) whereby ERĪ± Inhibitor drug tension and GCs sensitize neuroinflammatory responses is largely unknown. Interestingly, GCs upregulate the expression in the pattern recognition receptors (PRR) toll-like receptors (TLR) two and TLR4. These PRRs are involved in the recognition of each pathogen related molecular patterns (PAMPS) and danger related molecular patterns (DAMPS), and initiate signaling cascades that result in the synthesis and release of inflammatory mediators (Kawai and Akira, 2007; Salminen et al., 2008). In vitro studies have demonstrated that GCs can up-regulate TLR2 expression in epithelial cells by way of MAPK phosphatase-1 (MKP-1), which in turn inhibits p38 MAPK activity, a negative regulator for TLR2. This elevated expression of TLR2 leads to enhanced cytokine expression, which includes TNF- IL-1 and IL-8, upon challenge with an , inflammatory stimulus (Imasato et al., 2002). Similarly, Rozkova et al., found increased TLR two and TLR 4 expression on dendritic cells (DC) following GC therapy (Rozkova et al., 2006). Additionally, TNF- GCs cooperate to stimulate the promoter for TLR2 and andBrain Behav Immun. Author manuscript; readily available in PMC 2014 August 01.NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author ManuscriptWeber et al.Pagepotentially TLR4, growing receptor expression (Hermoso et al., 2004). Ultimately, in vivo findings demonstrate that TLR2 mRNA is upregulated 24 h immediately after subcutaneous (SC) injection of GCs (Frank et al., 2010) and TLR4 protein is elevated following repeated social tension (Wohleb et al., 2011). These information suggest that elevated levels of GCs, created by anxiety exposure, may well sensitize the neuroimmune microenvironment by upregulating expression of TLR2 and TLR4 on CNS innate immune cells. The objective in the present study was to investigate the involvement of TLR2 and TLR4 during a stressor and assess whether these receptors do mediate the stress-induced sensitized inflammatory response. A novel TLR2 and TLR4 antagonist, Oxidized 1-palmitoyl-2-arachidonyl-sn- glycero-3-phosphorylcholine (OxPAPC), was applied to block TLR2 and TLR4 activity through a stressor. Here we demonstrate that administration of OxPAPC in to the CNS prior to pressure prevents the exaggerated central (hippocampus) inflammatory response to a subsequent immune challenge. In vivo administration of central OxPAPC prior to anxiety also prevented potentiated inflammatory responses of microglia to LPS ex vivo.NIH-PA Author Manuscript2.1 Animals2. MethodsMale Sprague awley rats (600 day-old; Harlan Sprague awley, Inc., Indianapolis, IN, USA) had been pair-housed with food and water obtainable ad libitum. The colony was maintained at 25 on a 12-h light/dark cycle (lights on at 07:00 h). All animals were permitted 1 week of acclimatization towards the colony rooms ahead of experimentat.