脑红蛋白在内毒素休克大鼠模型中的表达变化

Change of neuroglobin in rats during endotoxic shock

目的:探讨内毒素休克模型大鼠海马、脑脊液、血浆脑红蛋白(Ngb)的表达变化及其意义.方法:选用SD大鼠70只,随机分为7组(n=10):对照组,经尾静脉注入0.5mL生理盐水;内毒素干预3,6,12,24,48,72h不同时间点组,经大鼠尾静脉注射0.5mL革兰氏阴性菌胞壁脂多糖(LPS),0.016g/kg,制作内毒素休克模型.对照组注射生理盐水后6h、内毒素干预不同时间点各组分别注射LPS后,于3,6,12,24,48,72h收集血浆、脑脊液,并处死大鼠留取海马.应用酶联免疫吸附法、免疫印迹法、免疫组织化学法检测标本中Ngb含量;应用干燥法检测海马组织含水量.结果:注射内毒素后,大鼠海马、脑脊液、血浆中Ngb含量显著高于对照组(P<0.01),48h达峰值,分别为34.89,22.01,14.01mg/L.免疫印迹法结果显示,内毒素干预不同时间点各组表达Mr均为17×103Ngb蛋白,Ngb蛋白表达量也显著高于对照组.注射内毒素后大鼠脑海马组织含水量明显高于对照组(P<0.01),48h含水量达峰值为0.8313.结论:Ngb表达量的上调与大鼠脑损害严重程度成正相关,其过度表达是全身性的,与内毒素处理的时程密切相关,Ngb表达上调可能是在内毒素休克状态下机体的内源性神经保护机制之一.

AIM： To study the changes and significance of neuroglobin（ Ngb ） expression in hippocampus, cerebrospinal fluid （CSF） and plasma in rats under endotoxic shock condition. METHODS： Seventy adult Sprague-Dawley（SD） rats were randomly divided into control group （0.5 mL normal saline was injected via vena caudalis）and experimental groups （0.5 mL endotoxin was injected via vena caudalis, O. 016 g/kg）. The brain tissues were examined respectively at the time point of 3, 6, 12,24, 48 and 72 h（n = 10）. The expression of Ngb over different periods was measured by enzyme-linked immunpsorbert assay （ ELISA ）, Western-blot and immunohistochemical method （IHC）. The brain water content （BWC） was measured by wet and dry weight method. RESULTS： ELISA showed that the Ngb concentrations in the plasma, CSF and hippocampus after endotoxin injection were significantly higher than those in control group （P 〈 0.01 ） and peaked at 48 h, which were 34.89, 22.01 and 14.01 mg/L respectively. Western Blot showed that the average molecular weight（Mr） of Ngb in each group was 17 × 10^3. The quantity of Ngb expression in the intervention groups was higher than that in the control group. The expression in 3 h group was the lowest and the expression in 48 h group was the highest. IHC showed that Ngb-immunoreactive product was located in the cytoplasm of the pyramidal neurons and was yellow-brown in color. The BWC in each group after endotoxin injection significantly increased（P〈0.01 ）and peaked at 48 h. The peak proportion of BWC was 0. 8313. CONCLUSION： Our results indicate that there is a positive correlation between the up-regulation of Ngb expression and the severity of brain impairment. The up-regulation of Ngb expression might be one of the endogenous nuroprotective mechanisms under endotoxie shock condition.