Myelopoietic response in mice exposed to acute cold/restraint stress: modulation by Chlorella vulgaris prophylactic treatment.

In this study, hematopoietic cells from mice pretreated with CVE and exposed to acute cold/restraint stress were stimulated in the presence of growth factors to form colonies, thus providing accurate information about the modulation of the green algae of the stress-induced changes in the hematopoietic response. Our results demonstrated that exposure to acute stress affected hematopoiesis. Mice exposed for a 2.5-hour time period of cold and restraint presented diminished clonal capacity for CFU-GM content per femur, which was decreased by as much as 50% compared with that in control mice, in spite of the significant increase in serum colony-stimulating activity (CSA). Treatment with 50 mg/kg CVE for 5 days, previously to the stress regimen, attenuates the effects of the stress, since comparable levels of myeloid progenitors were found in the bone marrow of both CVE/stress and control mice. Moreover, the sera from stressed mice pretreated with CVE further increased the CFU-GM formation. On the contrary, the spleen seemed to be less sensitive to acute stress in our experimental conditions. These findings are in line with our previous reports showing that the stress-induced reduction in bone marrow CFU-GM of rats exposed to electric shocks is mediated by activation of the HPA axis and by secretion of opioid agonists. No changes were observed in bone marrow, spleen and thymus total cell counts, and in relative organ weights. However, a 50% reduction in the body weight loss produced by the stress was observed in mice given the extract.