Mtm. Vanraaij et al., TIME-DEPENDENT DIFFERENTIAL CHANGES OF IMMUNE FUNCTION IN RATS EXPOSED TO CHRONIC INTERMITTENT NOISE, Physiology & behavior, 60(6), 1996, pp. 1527-1533
Noise is a highly relevant environmental and clinical stressor. Compar
ed to most other experimental stressors, noise is a modest activator o
f neuroendocrine pathways that mimic the situation in human health whe
re neuroendocrine activation by environmental stressors is often absen
t or difficult to establish. Little is known about the effects of nois
e exposure on the immune system. In the present work, the effects of a
low-intensity chronic intermittent unpredictable noise regimen on var
ious parameters of immune function was studied. Male wistar rats were
exposed to a randomized noise protocol (white noise, 85 dB, 2-20 kHz)
for 10 h per day, 15 min per h over a total period of 3 weeks. Control
animals were exposed to ambient sound only. Immune function was monit
ored after 24 h, 7 days, and 21 days of noise exposure. Noise induced
several significant changes in immune function in a time-dependent dif
ferential pattern involving both immunosuppression and immunoenhanceme
nt. After 24 h, serum IgM levels were increased and peripheral phagocy
tic activity was decreased. Splenic lymphocytic proliferation to mitog
ens was significantly decreased after 7 days, but slightly elevated af
ter 3 weeks. The activity of splenic NK cells was increased significan
tly after 24 h and 7 days, but suppressed after 3 weeks. These results
show that various parameters of immune function are affected differen
tially over time in a period of chronic mild noise stress, possibly du
e to sequential activation of different physiological mechanisms. Copy
right (C) 1996 Elsevier Science Inc.