, 1996, Elenkov et al., 2000, Woiciechowsky et al., 1998, Zhang et al., 2005 and Souza-Queiroz et al., 2008). B2-agonists inhibit IL-12 production (Panina-Bordignon et al., 1997), which is known to have a central role in the immune system by skewing the immune response towards Th1-type

responses. In this respect, studies from our laboratory and others (Hasegawa et al., 1997, Queiroz et al., 2002, Queiroz et al., 2011, Souza-Queiroz BI 2536 et al., 2008 and Torello et al., 2010) have proposed that CV has a direct myelostimulating outcome through inducing the Th1 response via activation of macrophages to produce IL-12 and IFN-γ. Previous findings from our laboratory demonstrated that pre-treatment with CV prevented this decrease in IFN-γ (Th1) and increase in IL-10 (Th2) after an acute foot-shock stressor (Souza-Queiroz et al., 2008). This reduction in IL-1 and TNF-α was prevented by treating mice with CV that were inoculated with tumors (Ramos et al., 2010) or exposed to lead (Queiroz et al., 2008 and Queiroz et al., 2011). These cytokines are known to stimulate the production of neutrophils from the bone marrow and to mediate chemoattraction of granulocytes from the circulation

to peripheral sites of injury. In the present study, we observed that the effects produced by both single and repeated stressors were suppressive, however, SST had a stronger impact on most of the parameters evaluated. This could be AZD6244 molecular weight explained by a decrease in hormone release due to glandular exhaustion or down-regulation of receptors,

among other possibilities, or it could also be explained by a reduction in the emotional impact initially caused by the stressful situation, thus leading to a decreased endocrine response over time (Armario, 2001). Delineating how stress influences hematopoiesis is important for developing potential pharmacological interventions to decrease the incidence of stress-induced immune dysfunction. BCKDHB Irrespective of the mechanisms involved, the immunomodulatory effect of CV on stressed mice may have an important role in protecting hosts from stressful situations, leading to an increase in the ability of the immune system to respond to this challenge (for an overview of the mechanisms of action from CV on stressed mice observed in this study, see Fig. 9). This research, which is part of the Ph.D. dissertation to be presented by Julia de Souza Queiroz to the Department de Farmacology/Hemocentro, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil, was supported by the FAPESP Foundation (No. 09/51886-3) and CNPq (No. 300764/2010-3); the authors wish to express their sincere gratitude. “
“Symbioses play a central role in the evolution of biological complexity and leaf-cutting ants are a prodigious example of this (Ness et al., 2010).