| Objective: Hypoxia can induce tissue damage. Study indicates that hypoxia can activate cytokine to induce inflammatory diseases through increasing adhesiveness of alveolar epithelial cells, neutrophils and macrophages. High altitude as an environmental stressor affects immune function by alterating both autonomic nervous system and endocrine function. Chronic intermittent hypobaric hypoxia (CIHH) can increase the resistance of body to ischemia/reperfusion or hypoxia/reoxygenation injury and has protective effects on the organ, such as heart, nerve and liver. But the effect of CIHH on immune function is not well defined. The purpose of this study is to elucidate the effect of CIHH on cellular immunity and humoral immunity in rat by using flow cytometry, immunohistochemistry and electron microscopy techniques.Methods: 48 male adult Sprague-Dawley rats were randomly divided into 4 groups: 14 days CIHH group (CIHH14), 28 days CIHH group (CIHH28), 42 days CIHH group (CIHH42), and control group (CON). The animals in CIHH groups were exposed to 14 days, 28days and 42 days hypobaric hypoxia (simulated 3000m altitude, 5 hrs per day), respectively. The weight and physical action of rats were observed in every week. Half of animals in each group were treated with normaxia and the other half animals were treated with 1h acute hypoxia. The animals were anesthetized with 25% urethane (1.25g/kg, ip), additinal doses were used when required. A midline incision was made on the ventral surface of the neck. The right common carotid arteries were cannulated for collecting arterial blood which were mixed with anticoag-ulant agents in vacuum tube.The ratio of blood and anticoagulant agents is 1:9. Serum was obtained by centrifuge 5 minutes with3ml blood. CD3, CD4, CD8 T lymphocytes, natural killer (NK) cells, IgG, cortisol, epirenamine and C-reactive protein were examined by flow cytometry and ELISA methods respectively. After stopping the reaction on reagent reference standard, read the optical density at 450 nm wavelength and calculate the concentration results according to the Log-Logit curve. Thymus and spleen were obtained after blood of rat was collecteds. Both of thymus and spleen were weighted and the ultrastructure of them was observed under electromicroscope.Results: 1. The body weight of CIHH rats was lower than that in Con rats, but no significant difference during first 14 days CIHH exposure. There was no significant difference of body weight gaining among every group. 2.Compared with CON, the indexes of thymus and spleen in CIHH14 rats were increased significantly; Spleen index, but not thymus index, was increased in CIHH28 and CIHH42 rats; There was no significant difference in the indexes of thymus and spleen between CIHH28 and CIHH42 rats. 3. Electron microscopy results showed that the thymus and spleen lymphocytes in CIHH14 rats were injured slightly, but no significant difference between CIHH28 and CON rats. The mitochondria in thymocytes and spleen lymphocytes of rat were injured during acute hypoxia, but the damage in CIHH28 rats was significant slighter than that in CON and CIHH14 rats. 4. Compared with CON, CIHH28 and CIHH42, CD8 in CIHH14 rats was decreased, ratios of CD4/CD8 was increased and NK was decreased; 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 was no significant changes of CD3,CD4,CD8 and NK in both CIHH28 and CIHH42 animals during acute hypoxia. 5. There were no obvious changes of IgG in CIHH rats before and after acute hypoxia. 6. 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 significant changes in CIHH rats before and after acute hypoxia.Conclusion: CIHH protects the immune function of rat against acute hypoxia, which is related with the regulation of neuroendocrine. |
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