8%, P < 0.05) AG14699 ( Fig. 6A). The HP number was also altered in this system (CTR: 9 ± 1%, SST: 5 ± 0.5% and RST: 7 ± 0.3%, P < 0.05) ( Fig. 6B). CV treatment prevented the changes induced by SST and RST in the number of HP and Gr1+Mac1+, maintaining levels similar to those observed in control animals ( Fig. 6A and B). Representative histogram is demonstrated in Figs. 6C and 6D. The levels of IL-1α and IL-6 were measured weekly (6–9 weeks) in the supernatants of LTBMC. As shown in Fig. 7 and Fig. 8, a progressive decline was observed in the levels of both cytokines in all groups studied. However, SST

and RST further reduced the production of IL-1α (Fig. 7 A and B) and IL-6 (Fig. 8 A and B) when compared with controls (P < 0.05). Treatment of stressed animals with CV prevented the decrease in the production

of both cytokines to control levels (P < 0.05). These results are consistent INCB024360 clinical trial with the increased ability of the stromal cell layer to display CFU-GM in vitro (item 3.4.1). Notably, treatment of non-stressed mice with CV caused a 15% increase in the levels of both cytokines. Because a variety of stressors may compromise the physiological role of the hematopoietic system in sustaining the proliferation and differentiation of progenitor cells to fulfill the continual cellular demands of the organism, we compared the impact caused by a single stressor (SST) or a repeated stressor (RST) on several parameters of the hematopoietic response in mice treated with CV using both in vivo and ex vivo systems. To our knowledge, this is the first study to compare the effects of a single or repeated application of an emotional stressor on the bone marrow (BM) and the functional activity of marrow stroma (measured by LTBMC). The latter is of great

importance, as the hematopoietic microenvironment supports blood Smoothened and immunocompetent cell generation ( Dorschkind, 1990). Our results showed a reduced number of hematopoietic progenitors (HP) from animals subjected to SST and RST, which corresponded with decreased CFU-GM numbers in both the BM and the LTBMC. In this case, SST induced a stronger suppression. We also measured the serum levels of colony-stimulating factors from plasma (CSA) and observed a significant increase after both stressors, influencing the proliferation and differentiation of BM-derived phagocytes. Persistent elevation of CSA levels during stress events serves as a continuing stimulus that supports the survival, proliferation, differentiation, and end functional activity of granulocytes and monocytes (Cheers et al., 1988, Guleria and Pollard, 2001, Kayashima et al., 1993, Wing et al., 1985 and Zhan et al., 1998). Treatment with CV produced a further increase in CSA levels in the BM of stressed mice (both SST and RST) and restored the number of HPs from BM and LTBMC to control levels.