Effects of Tail-suspension, Noise and Combination of Two Stresses on Immune Function of Rats

Abstract：Objective To investigate the effect of tail-suspension, noise stress and combination of them on immune function in rats. Methods The rats were divided into four different groups, A; control; B; noise stress ( 2 h) ;C; tail-suspension (30° 21 d) ;D; tail-suspension added noise stress. The body weight, thymus weight and spleen weight, circulating leukocytes and its distribution , T lymphocyte subpopulations (with flow cytome-try) and NO level in serum (with Griess method) of rats were determined after exposed to 21 d tail-suspension , 2 h noise stress and combination of them. Results Compared with group A, the body weight were significantly decreased (P <0. 01 ) , the percent of lymphocytes were also reduced (P <0. 05) , but the numbers and percents of circulating leukocytes, neutrophils were markedly increased (P <0. 01) in group C and D. T lymphocyte, Th subsets (both P<0.05) and Th/Tc ratio (P<0.01) increased in group D. The NO level in serum was markedly reduced (P<0.01) in B, C and D groups. Conclusion Tail-suspension had significant effects on the body weight, circulating leukocyte and its distribution, NO level in serum of rats. Noise stress had synergistic effect with tail-suspension on lymphocyte subsets.