| Objective: Chronic mountain sickness(CMS) is characterized by excessive erythrocytosis and serious hypoxemia and the reason of this disease is hypoxia. In this assay, the rat levels of hepcidin m RNA, GDF15 m RNA, protein expression and other relevant indicators of iron metabolism(including serum iron, serum ferritin) were measured in purpose of exploring the changes about iron metabolism in CMS rats, comparing to normoxic group.Methods: In this study, 59 healthy male Wistar rats from Lanzhou to Xining were involved in this study. After two weeks of adjustment period, the experiment was performed. all animal experiments described were approved by the institutional animal ethical committee. 59 healthy male Wistar rats of the same age and weight were randomized into two groups and maintained at an altitude of 2260 m(normoxic group, n=22) and a simulated altitude of 5000 m(hypoxia group, n=37) respectively. The rats of Normoxic group were fed in Xining natural conditions, the rats of normoxic group were fed in a hypobaric chamber(simulated altitude of 5000 m, 10.8% oxygen concentration, pressure of 54.02 Kpa, 22 h / d). After 30 days, the rats were anesthetized. The arterial blood was taken for gas analysis and blood cell analysis. The protein levels of hepcidin in rat liver and serum were detected by ELISA method, the levels of serum iron and serum ferritin were measured by Colorimetry and Immune chemiluminescence respectively, the rat liver hepcidin and Growth differentitation factor15(GDF15) m RNA levels were measured using real-time PCR, the protein levels of GDF15 in rat bone marrow were deteceted by Immunohistochemistry. In addition, the pulmonary artery pressure was detected in 6 rats of normoxic group and 5 rats of hypoxia group in the last. All data in the figures are used by statistical software SPSS17.0, firstly the data were checked up with test of normality, the data were normal or nearly normal distribution. All data were given as the mean±standard deviation(mean±SD). Calculations for statistical divergence among two groups were carried out by Independent samples Student’s t-test or the Wilcoxon rank sum test. All factors were analyzed by Spearman rank correlation. P < 0.05 was considered as statistically significant.Results:(1)The levels of HCT, HGB, mean pulmonary arterial pressure, serum iron, serum ferritin and rat sternum GDF15 integration were significantly higher in hypoxia group((71.33±5.34)%,(248.88±17.36)g/L,(66.06±17.36)mm Hg,(2.17±0.35)μmol/L,(11.52±1.58)μg/L, 5.08±0.70)than those in control group respectively((53.02±2.92)%,(185.69±12.14)g/L,(29.78±4.47)mm Hg,(0.87±0.11)μmol/L),(2.05±0.21)μg/L, 3.43±1.09)(all P <0.05). The levels of PLT, serum hepcidin concentration and hepcidin level in rat liver were lower in hypoxia group((472.09±117.90) × 109/L,(10.13±5.53)ng/ml,(64.04±40.30)ng/ml) than those in the normoxia group respectively((758.75±92.77) × 109/L,(14.16±4.49)ng/ml,( 154.79±95.08) ng/ml)(P<0.05). But there was no difference among normoxic group and hypoxia group about Sa O2(P>0.05).(2)The levels of rat liver hepcidin m RNA expression(0.67±0.33) in hypoxia group was less than that(1.03±0.27) in normoxia group(P<0.05); The levels of rat liver GDF15 m RNA expression(4.46±2.58) in hypoxia group were significantly increased compared with that of(1.10±0.54) in normoxia control group(P<0.05). The hepcidin m RNA, GDF15 m RNA expression in hypoxia group had no correlation with HGB or HCT(all P> 0.05).(3)The values of HGB in CMS group were positively correlated with those of SI, SF(r =0.925, 0.612), while the values of HGB in CMS group were negatively correlated with those of serum hepcidin levels(r=-0.405). The values of HCT in CMS group were positively correlated with those of SI, SF(r=0.889, 0.562), while the values of HCT in CMS group were negatively correlated with those of serum hepcidin levels(r=-0.367). The levels of SI were positively correlated with those of SF in CMS group(r=0.573, P=0.001), while the levels of SI were negatively correlated with serum hepcidin levels in CMS group(r=-0.43, P=0.014).Conclusions: Decreased hepcidin expression that regulate iron metabolism has been reported in response to hypoxia. The lower hepcidin concentrations observed in response to hypoxia may result in promoting body iron absorption and mobilization of iron stores, and further promoting erythropoiesis. GDF15 expression was increased in CMS and may related to erythroid maturation. GDF15 is signal molecules which linked erythroid generation and iron regulation. It further enrich the theoretical study of CMS. |
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