AIMTo elucidate the effect of CIHH on cellular immunity and humoral immunity in rat by using flow cytometry method, immunohistochemistry method and electron microscopy techniques.

METHODSForty-eight male adult Sprague-Dawley rats were randomly divided into 4 groups: control(CON) group, 14 days CIHH (CIHH14) group, 28 days CIHH (CIHH28) group, 42 days CIHH (CIHH42) group. The animals in CIHH groups were exposed to 14, 28 and 42 days hypobaric hypoxia(simulated 3 000 m altitude, 5 h per day), respectively. Half of the animals in each group was treated with normaxia and the other half animals were treated with acute hypoxia for 1 h. CD3, CD4, CD8 T lymphocytes, natural killer (NK) cells, IgG, cortisol, epirenamine and C-reactive protein were examined. The weight and ultrastructure of thymus and spleen were observed.

RESULTS(1) Compared with CON, both indexes of thymus and spleen in CIHH14 rats were increased significantly. Spleen index, but not thymus index, was increased in CIHH28 and CIHH42 rats. The thymocytes and spleen cytes in rat were injuryed during acute hypoxia, but the damage in CIHH rats was significant slighter than that in CON rats. (2) Compared with CON, CIHH28 and CIHH42, CD8 in CIHH14 rats were decreased, ratios of CD4/CD8 was increased and NK was decreased. (3) The rats of CON during acute hypoxia showed that CD4 was increased, CD8 was decreased, ratio of CD4/CD8 was elevated, and NK was increased. But there were no significant changes of CD3, CD4, CD8 and NK in CIHH28 and CIHH42 animals during acute hypoxia. (4) Compared with CON, CIHH28 and CIHH42, cortisol in CIHH14 rats was increased obviously, Epirenamine, cortisol and C-reactive protein in CON rats were increased, but there were no obvious changes in CIHH rats before and after acute hypoxia.

CONCLUSIONCIHH protects the immune function of rat against acute hypoxia, which is related with the regulation of neuroendocrine.