Modulations of immune functions and oxidative status induced by noise stress.

Noise has long been realized as an environmental stress causing physiological, psychological and behavioral changes in humans. The aim of the present study was to determine the effect of acute or chronic noise stress on both cellular and humoral immune responses and oxidative status. BALB/c mice were exposed to 90 dB (A) white noise 5 h per day for either 3 d or 4 wk. Hormone levels, splenic lymphocyte proliferation, lymphocyte subsets in spleen and thymus, serum antibody and oxidative status were determined. A 3-d exposure to noise stress resulted in increased hormone levels, splenic lymphoproliferation and serum IgM. On the other hand, a 4-wk exposure to noise stress caused a reduction of splenic lymphoproliferation, splenic CD4(+) cells and serum IgG, but hormone levels and urinary 8-hydroxy-2'deoxyguanosine (8-OHdG) were increased. These results imply that acute exposure to noise stress may enhance immune responses, whereas chronic exposure to noise stress may suppress both cellular and humoral immune functions. The effect of noise stress on immune functions may be related to neuroendocrine modulation and oxidative imbalance as well.